I have 2 plastic bottles I bought in 2019 to replace all my accumulators. Life got in the way and it never happened. I need to do it soon. Should I dispose of those bottles and buy new ones?
The ABCs of AHC - How to Measure, Flush, and Adjust all in one place
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2001LC
SILVER Star
Likely okay. Seems issue began in 2021. I had case from early 2021 that was fine.
You should filter it through a coffee filter. If you see jell, I'd toss or return. But at Local Lexus Dealership, they filter and use.
You should filter it through a coffee filter. If you see jell, I'd toss or return. But at Local Lexus Dealership, they filter and use.
If anyone wants to go a step further and refresh globes and front suspension bushings, here it my writeup - Successful AHC refresh - my experience and quick writeup - https://forum.ih8mud.com/threads/successful-ahc-refresh-my-experience-and-quick-writeup.1279980/
Ok, this thread is a lot to digest for someone who is not used to AHC and never owned a 100 series before. I am set to buy an ‘05 LX470 to build a moderate overland ER, and thought I’d want to delete the AHC just for the sake of simplicity. But I’m beginning to think I should a good thing alone (at least for now).
So first of all, HUGE thank you to everyone who has put their heads together to get this knowledge compiled and usable to a total noob like me.
Second, does anyone have the software in the upstate SC/Asheville NC area? I’d be willing to buy you a nice steak dinner for some help checking out the current state of my suspension and maybe make s9me adjustments (assuming everything goes well Monday)
zac
So first of all, HUGE thank you to everyone who has put their heads together to get this knowledge compiled and usable to a total noob like me.
Second, does anyone have the software in the upstate SC/Asheville NC area? I’d be willing to buy you a nice steak dinner for some help checking out the current state of my suspension and maybe make s9me adjustments (assuming everything goes well Monday)
zac
If you are available next Saturday I'll be passing thru your area and have the necessary software and cables to check the health of the system.
I own two LX470s both with 200000 + miles and running on AHC. I think the system is great when maintained.
PM me if you are interested.
Mike
Someone who knows what they are doing with the software needed is the way to go if you haven’t yet figured out AHC. The tech stream sw may do more but you can measure everything you need to adjust AHC using this code reader and an iPhone.
OBDLink MX+ OBD2 Bluetooth... Amazon product ASIN B07JFRFJG6
OBDLink MX+ OBD2 Bluetooth... Amazon product ASIN B07JFRFJG6
Would it be normal to have to only re-index one torsion bar?
My 98 LX had the left side about an inch lower than the right, so I finally got around to fix this after much reading on how to do this correctly. Truck has 270k km on it, PO did minimal service at the local Lexus dealer (regular fluid changes (AHC about 50k km ago), but only fixed items when the car wouldn't run.
The left linkage was seized and not securely connected on the top bracket which gave random incorrect readings most of the time, so I ordered a new one and started once it arrived.
- With AHC off, I adjusted torsion bars to level out the front. Required tightening the left side 8 turns and loosening the right side 9 turns.
- Adjusted linkages to have Techstream report height sensors 0 to -.1 when at N. Measurements at N were 19.7 inches hub centre to fender lip.
- Checked graduations, there were 9 graduations when going from H to L.
- For pressures, they ended up at 8.2 front, 6.8 rear, and 10.6 acc. The front is quite high, so it looks like I will need to tighten the torsion bars about 8 turns to bring the pressure down to spec. There are only about 4 turns left to tighten the left, so I will need to re-index.
Post 211 mentioned that if the torsion bars are indexed differently, there will be a lean, however in my case I will have the bars indexed differently to remove a lean.
This had me wondering that with such a difference between both bar's settings (one adjusted way down, one way up) if I need to worry about the cause of the difference, or to just go and re-index the left side then adjust to get the pressures within spec.
My 98 LX had the left side about an inch lower than the right, so I finally got around to fix this after much reading on how to do this correctly. Truck has 270k km on it, PO did minimal service at the local Lexus dealer (regular fluid changes (AHC about 50k km ago), but only fixed items when the car wouldn't run.
The left linkage was seized and not securely connected on the top bracket which gave random incorrect readings most of the time, so I ordered a new one and started once it arrived.
- With AHC off, I adjusted torsion bars to level out the front. Required tightening the left side 8 turns and loosening the right side 9 turns.
- Adjusted linkages to have Techstream report height sensors 0 to -.1 when at N. Measurements at N were 19.7 inches hub centre to fender lip.
- Checked graduations, there were 9 graduations when going from H to L.
- For pressures, they ended up at 8.2 front, 6.8 rear, and 10.6 acc. The front is quite high, so it looks like I will need to tighten the torsion bars about 8 turns to bring the pressure down to spec. There are only about 4 turns left to tighten the left, so I will need to re-index.
Post 211 mentioned that if the torsion bars are indexed differently, there will be a lean, however in my case I will have the bars indexed differently to remove a lean.
This had me wondering that with such a difference between both bar's settings (one adjusted way down, one way up) if I need to worry about the cause of the difference, or to just go and re-index the left side then adjust to get the pressures within spec.
uHu
Bridgeburner
1 - Yes, the left one.
2 - It could be that the left coil is more weakened than the right one. If you change the coils, and get a stronger one on the left, it could be that you don't need indexing. Of standard OEM coils, you have pink, purple and brown to choose between. To me, only the brown makes any sense, and the pink is to weak for anything. Alternatively a brown on the left and a purple on right.
All cruisers sag more on the left, with both the tank and the driver to the left of center. Over time that adds up to a left lean.
2001LC
SILVER Star
@uHu @IndroCruise @suprarx7nut @PADDO anyone?
Would running the pump motor, via a jumper from 12 volt battery. Raise the vehicle from L, when AHC flashing off on dash (in fail safe mode)?
I'm wondering if the "controller" may close a valve during fail safe, block any fluid from entering or leaving it and thus globes/shocks/accumulator?
If so, is there a way to override and open the valve?
Would running the pump motor, via a jumper from 12 volt battery. Raise the vehicle from L, when AHC flashing off on dash (in fail safe mode)?
I'm wondering if the "controller" may close a valve during fail safe, block any fluid from entering or leaving it and thus globes/shocks/accumulator?
If so, is there a way to override and open the valve?
I'm pretty sure the valves to run fluid from the pump to the front or rear are shut until specifically instructed to open. You'd have to manipulate those valves as well as the pump to get any height change to occur. In the AHC OFF flashing light mode, I believe the pump is isolated and the hydraulic system retains whatever pressure it was able to build up before the fail safe trigger.
@2001LC I just did that couple of days ago. Negative, forcing the pump via 12V does not rise the vehicle. The solenoids behind the accumulator need to be operated. The system closes the front circuit when operating the rear and vice versa. What you can do is use the "Active Test" described in this post by @IndroCruise
DLC1 is the "DIAGNOSTICS" plug in the passenger side of the engine bay. When you short Ts & E1 and start the car, a bunch of lights will start flashing on the dashboard.
You can then rise/lower front and rear.
Make sure not to rise any side above the normal H height - the system is manually operated and won't stop you.
You can also lower it A LOT this way. Normal L goes to -40mm, if you hold the down active test it will go to -80mm in front! -60 in te rear with Kings springs for me.
If the system is in fail safe due to some pump/motor issue the Active Test will not do anything. I was getting C1762 immediately on start and this was not working until I resolved it.
DLC1 is the "DIAGNOSTICS" plug in the passenger side of the engine bay. When you short Ts & E1 and start the car, a bunch of lights will start flashing on the dashboard.
You can then rise/lower front and rear.
Make sure not to rise any side above the normal H height - the system is manually operated and won't stop you.
You can also lower it A LOT this way. Normal L goes to -40mm, if you hold the down active test it will go to -80mm in front! -60 in te rear with Kings springs for me.
If the system is in fail safe due to some pump/motor issue the Active Test will not do anything. I was getting C1762 immediately on start and this was not working until I resolved it.
2001LC
SILVER Star
Thanks Andy! That is what i'm thinking.
Thanks! @Moridinbg I'll try it today.
Guys;
I know the motor runs strong, as I jumped it. This will help me confirm the pump is also working okay, and fluid is building pressure all the way to shock/globes.
With so much bad fluid (jelling) around, clogging pumps. I wanted and easy test. So I made a jumper, with a wire housing block w/pig tails, With~4 feet of old heavy gauge extension cord for wires and spring clamps, to clamp to battery. It allows me to simple plug into motor and hook to battery.
~$20 Pump motor jumper.
Here's what I'm working on now, a troublesome case of AHC in fail safe (flashing off), on a 01LX w/~150K miles rust free:
It's AHC failed last year and was driven on for months in fail safe with a very bouncy ride, from what I understand.
It then came to me and I found DTC:
C1736 Accumulator Solenoid Circuit,
C1762 Abnormal Oil pressure pump.
The diagnostic tree lead me to AHC CPU, which I ended up not testing at that time. I had spoken with you Andy, on a similar case you had. In which you found a dead wire. Which I understood to be in harness on top of the LH rear 1/4 frame. Which until you found it, I didn't realize the AHC wires ran that far back of rear height sensor.
Anyhow, after disconnecting and reconnecting the LH rear 1/4 wire harness wire housing block. I got some results in AHC, in that it worked again, but failed again. Once I did get working, the rear was high. I messed with rear sensor and got it working better, but still rear was high. I ended up, replacing rear sensor adjuster arm, which found the ball joints frozen. It did not help a height come down. So I tossed in a "used" rear height sensor. Now system work fine, rear height came down to normal in N. I ended finding all 3 height sensor linking/adjusting arms balls frozen and replaced all 3 arms. AHC worked repeatedly in the shop.
I flushed & adjusted (t-bars and sensors). Got pressure of: temp 81F, frt 6.9MPa, Rear 6.5MPa, Acc 10.6MPa, 10+ grads.. All seem good!
Took on long test drive. Actively working AHC H to L, L to H, confront to sport repeatedly. So much so it failed again. Which I assumed, I worked and heated fluid to much, so shut it down AHC. With short rest (cool DN), than key off and on again. AHC worked fine again. I repeated this 3 or 4 times, causing failure/corrected (worked) each time.
Read pressure again, I found front changed from where I set it. In that front, pressure went up to around 8.2 to 8.6MPa (avg 6.4MPa). Which I assumed was due to settling of suspension after driving, putting more weight on AHC. I cranked CW on T-bars and got pressure back to proper range. Rear pressure high at 6.5MPa but not terrible. Plan at this point, was to see how system performed over time. Before addressing rear coils springs to reduce pressure and set up for carrying bikes on a rack (not yet on hitch).
Anyhow, after this last adjust. I drove around for over next week, and the AHC worked great. Than I turned vehicle over to owner. Which drove for 3 months ~2,500 miles (mostly in mountains), without issue and loved AHC feel and vehicle handling.
Dang if system didn't fail again. It would fail about 45 minutes into HWY drives in the mountains. As it turns out, the failure started happening after a shop installed an aftermarket radio and very powerful AMP. Which required they do some aftermarket wiring (I hate that stuff)
Back in my shop. I got it working after washing underside, which I though perhaps water cooled system. Maybe reducing resistance in wires and or controller. AHC failed again as I played with up and DN. I ended up unplugging rear 1/4 wire housing block again to get working. This worked to get working, but did not always get working.
Once working I found front pressure high again, higher than I last had set at 3 months/2,500 mile earlier, at 6.9MPa. It was now at FRT pressure of ~8.4MPa (average or 3 readings)
After 2 CW of T-bars LH & RH. Pressure dropped from ~8.4MPa to ~6.4MPA with a temp of 131F. Which temp of fluid came up fast. Seem to be a lot of change for only 2 CW cranks on T-bar. Anyhow system worked again and was not failing in shop. So I took on 100 miles test drive.
System failed again on test drive when foot brake applied. Did very well first 50 miles of test drive. It only failed when I got off HWY as I braked, to come to stop. HUMMMM! Anyhow, I had to drive about 5 minutes in safe mode (OFF flashing), until I could pull off road. Once I shut DN fluid temp read 88F (may have cooled while driving AHC OFF), on a cool day OAT ~60F. overcast. I let rest, and than system worked again after key off. Working fine for 50 miles drive back, again until I pulled off HWY and braked.
Once back in shop after cooling and then playing with up and DN. AHC failed again. I once again found front pressure had gone higher in front.
I've now maxed LH CW cranks on T-bar and added extra CW RH T-bar and did some other stuff. Like plugging in other used height sensors, replacing front globes with good working used ones. Replace pressure sensor with a used one.
Interesting: Every time I went into active test through tech stream, when last working. The moment I activate any test, system would shut down, go back to safe mode.
I can not get system out of fail safe (flashing off) any more. And have since, replaced front globes and bleed fluid off (no air bubbles). I'm now on the bump stops more or less.
AHC CPU SHB & SHG value below limit of ~5 Volt at 3.41V during a test. I hooked up another AHC computer, which reads within spec voltage, 5 volts. So I assume good as was advertised.
System will not clear DTC of C1736 and C1776, and not come out of safe mode.
Any thoughts guys and whats going on here?
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Could it be contamination and/or blocked pipes? Jumping pressure & C1736 Accumulator Solenoid Circuit sounds suspicious. C1765 is a catch all for when the system can't get to pressure immediately or over pressurises. Or maybe bad wiring? Aftermarket wiring for radio is another suspect.
AHC CPU SHB & SHG value below limit of ~5 Volt at 3.41V, while OK with another ECU is a different pretty big red flag.
Wires go all the way to the back, because there is a grommet back there for the wires to come out of the cabin. There are very few grommets for wires to leave the cab in fact.
Here are a few photos of the AHC harness from my chassis galvanisation adventure. You can see the harness coming from the rear terminates at the FL globe and the solenoid block
And this is where the harness connects to the harness coming out of the cab, splitting to the right side and also connecting to the rear sensor. It goes forward to the RL globe and then the FL and solenoids
You can check for continuity between the AHC ECU and the plugs in the rear and at the solenoids.
AHC CPU SHB & SHG value below limit of ~5 Volt at 3.41V, while OK with another ECU is a different pretty big red flag.
Wires go all the way to the back, because there is a grommet back there for the wires to come out of the cabin. There are very few grommets for wires to leave the cab in fact.
Here are a few photos of the AHC harness from my chassis galvanisation adventure. You can see the harness coming from the rear terminates at the FL globe and the solenoid block
And this is where the harness connects to the harness coming out of the cab, splitting to the right side and also connecting to the rear sensor. It goes forward to the RL globe and then the FL and solenoids
You can check for continuity between the AHC ECU and the plugs in the rear and at the solenoids.
2001LC
SILVER Star
Thanks @Moridinbg. I've followed you thread on your frame off restoration. Kudos to you my friend, it is some great work you've done!
Love the pictures. They are really helpful, for me to visualize. So I should be able to check continuity between CPU and the wire housing blocks (plug) at rear 1/4. Than rear 1/4 plug to H. senors rear, controller, globes and accumulator. BTW: I did do the FSM prescribed check/test at controller and accumulator wire housings. They tested to spec (Okay).
I'd not consider blockage in pipe(s), just pump. I'll see if I can raise by jumping pump w/12V. I may also pull a pipe flare at controller and see if it flow out, while pumping.
Another thought just came to me, because of another thread. Where it was just posted a new pump cured. Old pump not clogged, but he seem to think old was overheating fluid. Hummm! Not sure this would explain, why my front pressure keep going up. But I did suspect I was get fluid to hot to fast.
I should have also mention this 01LX, has had electrical issue in the distant pasted (1st few years after build date). Seems mirror CPU changed twice. By two different Lexus dealerships years and states apart. Mirrors and steering tele, not functioning again. No history or signs of water entry. That and failure just after new aftermarket wiring, has me concerned.
Can you confirm: I've circled all the AHC wire housing blocks in this picture?
I've circled in red what I think is LH & RH wheel speed sensor, can you confirm?
Also can you tell me what wire housing blocks (plugs) # 1, # 2 and #3 circled in green are for?
Love the pictures. They are really helpful, for me to visualize. So I should be able to check continuity between CPU and the wire housing blocks (plug) at rear 1/4. Than rear 1/4 plug to H. senors rear, controller, globes and accumulator. BTW: I did do the FSM prescribed check/test at controller and accumulator wire housings. They tested to spec (Okay).
I'd not consider blockage in pipe(s), just pump. I'll see if I can raise by jumping pump w/12V. I may also pull a pipe flare at controller and see if it flow out, while pumping.
Another thought just came to me, because of another thread. Where it was just posted a new pump cured. Old pump not clogged, but he seem to think old was overheating fluid. Hummm! Not sure this would explain, why my front pressure keep going up. But I did suspect I was get fluid to hot to fast.
I should have also mention this 01LX, has had electrical issue in the distant pasted (1st few years after build date). Seems mirror CPU changed twice. By two different Lexus dealerships years and states apart. Mirrors and steering tele, not functioning again. No history or signs of water entry. That and failure just after new aftermarket wiring, has me concerned.
Can you confirm: I've circled all the AHC wire housing blocks in this picture?
I've circled in red what I think is LH & RH wheel speed sensor, can you confirm?
Also can you tell me what wire housing blocks (plugs) # 1, # 2 and #3 circled in green are for?
I'd put money on it that you've got a bad conductor (wire) in the AHC system. Given my experience, I'd double down on my bet that the problem is in that section of wire that runs to/from the rear 1/4 on the driver's side.
Have you checked resistance of the accum solenoid at the solenoid and then again at the terminals within the connector in the rear 1/4 (B1 I think)? And then again at the ECU (this plug is a huge pain so don't go this far unless all other resistances look good)? I bet the resistance checks will reveal a bad reading at one of the junctions. Then the task becomes simpler (not necessarily easy, but simple). I've got wiring diagrams for the early and late model years. Happy to post up some pics if that would help you chase after that bad conductor.
Your situation sounds very similar to the one I worked on last year. All it takes is one bad section of wire to give both the codes you're seeing. Once the system detects that solenoid is MIA, you're completely dead in the water. The system goes into safe mode and disallows most AHC functions and tests.
Keep it simple and chase the wire that's causing that C1736 code.
2001LC
SILVER Star
I've got it working again!
To answer your question Andy. I did check the continuity of accumulator and it's wires. I also the controller and it's wires. I've now checked continuity from CPU (new/used AHC CPU, which test good) to rear 1/4, and on to rear height sensor, accumulator and controller. In addition to checking many other points of AHC system, while following diagnostic tree based on various DTC I've had and suggestion from the forum. To many list, much less remember. It has been the most extensive diagnostic work I've done on any single 100 series AHC. Yet I can't say for sure, why it now works "again"?
A little what did last few days:
To gain accesses to rear wires under vehicle. Which vehicle was sitting on the bump stop. Due to me draining AHC fluid from globe bleeders. So I could check for air and replacing front globes as a test. I did this due to declining front pressure, which had me cranking CW on torsion bars repeatedly. Repeatedly, to keep getting front pressure back in line (front keep going from ~6.9 to ~8.5MPa). I lifted the rear of vehicle and sat jack-stands under rear frame rails. Allowing rear wheels to hang freely. Consequently, fully extending rear height sensors (the used one I installed 2,500 miles ago). I then pulled all 3 wire housing blocks from under 1/4 tip, controller, accumulator and rear height sensors.
With all wire housing blocks disconnected. I studied wire color codes, tracing which went where. Checking continuity as I did. Interesting I found the wire block with longer wire housings, separably mounted from other two on the frame. The one I had though was the main AHC wire housing block. Because it was only one I disconnecting, giving me results 2,500 miles ago. Was not! It was the two wire housing blocks, one black one gray mounted on same bracket together on frame. The black block, housed all the wires to accumulator, controller & rear high sensor except one. That one, was the Blue/red to accumulator from the gray housing block.
This gray wire housing block female plug, plugs to gray male mounted with the black housing block on one bracket mounting it to the frame. Had the one Blue/red wire to accumulator.
Looked like water enter at some point and kind had a moldy appearance. Which is interesting since the C1736 DTC, does deal with accumulator.
The gray wire housing block plug
The gray & black female wire housing blocks on one bracket, coming out from rear 1/4 cargo area
Wire housing blocks just inside LH drivers foot well. Near floor board and door threshold.
I cleaned the wire housing blocks with HP air and plastic safe spray contact cleaner. Added some dielectric grease to help lube and seal out water. I went on checking continuity. I did not check from CPU to the accumulator, until after cleaning this gray wire housing block. Had I, it likely would have test okay. But a may have failed a resistance test, with high resistance. If I even knew what the resistance should be, which I don't.
Anyway it is working at the moment. I can't say for certain why. I think is was a combination of issues. Which has been the story with this 100 series, on other electrical issues also. It's had, other (non AHC) electrical issue going back 20 years in it's history.
So was it the:
The failed AHC CPU!
Wire blocks moldy (appearance), increasing resistance confusing CPU.
Front globes.
Rear sensor. (Changing position, by jacking up vehicle).
Unplugging, cleaning and reconnecting the many wire housing blocks. Most notably the the gray moldy one.
A combination of the above.
I suspect the gray wire housing block increasing resistance. That perhaps that had some cause and affect on AHC CPU, damaging it. That the CPU was effecting the front pressure reading in tech stream. Which means the old globes are likely good. Which I'll be take on test drive than likely swap back in the old globes. I'm still concern the height sensors have seen better days. So sensor refresh is likely in the cards. But I liked to see how the system preforms over the summer. Before putting more money (time & parts into it).
I'll get it all put back together. Of which the AHC CPU upper nut, will be the biggest PITA. Than test drive and hope! As I really don't know why it now works, yet again!
I did have to back off (CCW) T-bars, to bring pressure back up.
Here's readings in tech stream, before test driving and settling suspension:
Note: +B power source 12.8 volts, is bit lower than IG. But much better than when it was in fail-safe. I'm really not sure of what I should see in volts. Should I match IC volts, be above or below with +B?
Temp seem good at 103F, after about 10 cycling L to H, over 20 minutes. I saw in another thread where supposed bad pump, temp hitting near 180F. So I'm hopeful, the bad pump and accumulator TSB, is not a part of this rig issues. But it is in the date range of TSB.
No Codes.
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PabloCruise
SILVER Star
Interesting! I flushed my system in early July of '21...
2001LC
SILVER Star
The post I've read. The AHC pump failed very fast, or as soon as started up after flush.
I bet that grey connector ( I believe that's B1) is/was at least a part of the problem. That connector should look pristine within the seal. That one appears to have been compromised. I've never run across that, even on my mk3 Supras that are another 10-20 years old. Bizarre. Some connector housings you can buy new from Toyota for a very reasonable amount that one would be a good one to swap out if possible. It's critical those stay sealed and that one appears to be pretty well unsealed, haha. Usually the black seal within the sealing line is a deep gloss black. That seal just looks old and dry all around. It could just be the photo, but it looks like there's no jet black seal to be seen there.I've got it working again!
To answer your question Andy. I did check the continuity of accumulator and it's wires. I also the controller and it's wires. I've now checked continuity from CPU (new/used AHC CPU, which test good) to rear 1/4, and on to rear height sensor, accumulator and controller. In addition to checking many other points of AHC system, while following diagnostic tree based on various DTC I've had and suggestion from the forum. To many list, much less remember. It has been the most extensive diagnostic work I've done on any single 100 series AHC. Yet I can't say for sure, why it now works "again"?
A little what did last few days:
To gain accesses to rear wires under vehicle. Which vehicle was sitting on the bump stop. Due to me draining AHC fluid from globe bleeders. So I could check for air and replacing front globes as a test. I did this due to declining front pressure, which had me cranking CW on torsion bars repeatedly. Repeatedly, to keep getting front pressure back in line (front keep going from ~6.9 to ~8.5MPa). I lifted the rear of vehicle and sat jack-stands under rear frame rails. Allowing rear wheels to hang freely. Consequently, fully extending rear height sensors (the used one I installed 2,500 miles ago). I then pulled all 3 wire housing blocks from under 1/4 tip, controller, accumulator and rear height sensors.
With all wire housing blocks disconnected. I studied wire color codes, tracing which went where. Checking continuity as I did. Interesting I found the wire block with longer wire housings, separably mounted from other two on the frame. The one I had though was the main AHC wire housing block. Because it was only one I disconnecting, giving me results 2,500 miles ago. Was not! It was the two wire housing blocks, one black one gray mounted on same bracket together on frame. The black block, housed all the wires to accumulator, controller & rear high sensor except one. That one, was the Blue/red to accumulator from the gray housing block.
This gray wire housing block female plug, plugs to gray male mounted with the black housing block on one bracket mounting it to the frame. Had the one Blue/red wire to accumulator.
Looked like water enter at some point and kind had a moldy appearance. Which is interesting since the C1736 DTC, does deal with accumulator.
View attachment 3025696
The gray wire housing block plug
View attachment 3025740
The gray & black female wire housing blocks on one bracket, coming out from rear 1/4 cargo area
View attachment 3025741
Wire housing blocks just inside LH drivers foot well. Near floor board and door threshold.
View attachment 3025754
I cleaned the wire housing blocks with HP air and plastic safe spray contact cleaner. Added some dielectric grease to help lube and seal out water. I went on checking continuity. I did not check from CPU to the accumulator, until after cleaning this gray wire housing block. Had I, it likely would have test okay. But a may have failed a resistance test, with high resistance. If I even knew what the resistance should be, which I don't.
Anyway it is working at the moment. I can't say for certain why. I think is was a combination of issues. Which has been the story with this 100 series, on other electrical issues also. It's had, other (non AHC) electrical issue going back 20 years in it's history.
So was it the:
The failed AHC CPU!
Wire blocks moldy (appearance), increasing resistance confusing CPU.
Front globes.
Rear sensor. (Changing position, by jacking up vehicle).
Unplugging, cleaning and reconnecting the many wire housing blocks. Most notably the the gray moldy one.
A combination of the above.
I suspect the gray wire housing block increasing resistance. That perhaps that had some cause and affect on AHC CPU, damaging it. That the CPU was effecting the front pressure reading in tech stream. Which means the old globes are likely good. Which I'll be take on test drive than likely swap back in the old globes. I'm still concern the height sensors have seen better days. So sensor refresh is likely in the cards. But I liked to see how the system preforms over the summer. Before putting more money (time & parts into it).
I'll get it all put back together. Of which the AHC CPU upper nut, will be the biggest PITA. Than test drive and hope! As I really don't know why it now works, yet again!
I did have to back off (CCW) T-bars, to bring pressure back up.
Here's readings in tech stream, before test driving and settling suspension:
Note: +B power source 12.8 volts, is bit lower than IG. But much better than when it was in fail-safe. I'm really not sure of what I should see in volts. Should I match IC volts, be above or below with +B?
Temp seem good at 103F, after about 10 cycling L to H, over 20 minutes. I saw in another thread where supposed bad pump, temp hitting near 180F. So I'm hopeful, the bad pump and accumulator TSB, is not a part of this rig issues. But it is in the date range of TSB.
No Codes.
View attachment 3025721
2001LC
SILVER Star
I do agree, it would seem this wire block housing had some part in the failure of AHC. Good Idea Andy, replacing the connectors. For now, we're going to see how the system behaves as is.
It may be best to just replace the harnesses
I would have like to test resistance of all wires, that I checked for continuity. But for that I'd need new wire harnesses to compare with.
There was something else on harness I noticed. It was what looked like heat damage on wire harness outer wrapping (Wire Loom Tubing - Split).
Wire harness at rear 1/4. Looks like heat damage, but wires inside seemed okay. At least I couldn't see any wire damage.
Even the 2 (1 at duel block hanger and 1 at single block holder) plastic clips holding harness on frame, were brittle and falling apart. Not what I'd expect on a clean 150K 01LX mostly garaged and rust free. I did strap the harness to the frame. Since these clips weren't very securing well in current condition. Which should keep from bouncing around.
The computer did test bad, and replacement did test good. Both before and after I cleaned up wire housing blocks. So it was a bad AHC CPU. Why it went bad I can only speculate. But could be increased resistance in wiring over time. Could be aftermarket AMP & radio installer some how shorted.
This harnesses wires and its housing blocks, may have/are increased resistance. It could be why I kept seeing the +B voltage about 1 volt lower the IG voltage at most times, while working. Never have I seen +B higher, in this 01LX. +B would drop to near 1 volt when in fail-safe. But this is pure guessing with little basis. As I've never paid much attention to the voltages displayed in tech stream. Nor do I actually know what their telling me/us. I'll also note, IG was about 1 volt below what I'd see at battery, before cleaning up wire housing blocks. I did see improvement after, where IG was at or near battery volt, but still +B below each time I looked (best was .5 volt lower). Which perhaps, just happen to be when I was looking. I have seen other screen shot in mud and in my shop (looking over pictures on file) where +B higher voltage at times, than IG volts.
Can anyone explain what the IG and +B voltage is telling us?
I also tested the ride, with my (used 2007) front globes on. Which the ride was better, and better control with dampener (comfort to sport).
Addition the height sensors are aged. More so than 01 with 150K miles would be, IMHO. In that all sensor adjuster arms ball joints were frozen.
So to really get this one up to snuff, will be and expensive proposition. As I'm thinking best may be new wire harnesses, globes and height sensors.
It may be best to just replace the harnesses
I would have like to test resistance of all wires, that I checked for continuity. But for that I'd need new wire harnesses to compare with.
There was something else on harness I noticed. It was what looked like heat damage on wire harness outer wrapping (Wire Loom Tubing - Split).
Wire harness at rear 1/4. Looks like heat damage, but wires inside seemed okay. At least I couldn't see any wire damage.
Even the 2 (1 at duel block hanger and 1 at single block holder) plastic clips holding harness on frame, were brittle and falling apart. Not what I'd expect on a clean 150K 01LX mostly garaged and rust free. I did strap the harness to the frame. Since these clips weren't very securing well in current condition. Which should keep from bouncing around.
The computer did test bad, and replacement did test good. Both before and after I cleaned up wire housing blocks. So it was a bad AHC CPU. Why it went bad I can only speculate. But could be increased resistance in wiring over time. Could be aftermarket AMP & radio installer some how shorted.
This harnesses wires and its housing blocks, may have/are increased resistance. It could be why I kept seeing the +B voltage about 1 volt lower the IG voltage at most times, while working. Never have I seen +B higher, in this 01LX. +B would drop to near 1 volt when in fail-safe. But this is pure guessing with little basis. As I've never paid much attention to the voltages displayed in tech stream. Nor do I actually know what their telling me/us. I'll also note, IG was about 1 volt below what I'd see at battery, before cleaning up wire housing blocks. I did see improvement after, where IG was at or near battery volt, but still +B below each time I looked (best was .5 volt lower). Which perhaps, just happen to be when I was looking. I have seen other screen shot in mud and in my shop (looking over pictures on file) where +B higher voltage at times, than IG volts.
Can anyone explain what the IG and +B voltage is telling us?
I also tested the ride, with my (used 2007) front globes on. Which the ride was better, and better control with dampener (comfort to sport).
Addition the height sensors are aged. More so than 01 with 150K miles would be, IMHO. In that all sensor adjuster arms ball joints were frozen.
So to really get this one up to snuff, will be and expensive proposition. As I'm thinking best may be new wire harnesses, globes and height sensors.