AHC help! (1 Viewer)

[kmr12345]

Yeah I can do my own work just not familiar with the technicalities of it. I should show as a silver star now. I will just buy the new coils not a huge price difference and probably the better route. So if it isn't driving up to snuff at this point I should think about replacing the globes correct?

 

[PADDO]

With pressures dialed in, fresh fluid and the front damping still isn't satisfactory then new front globes are pretty much called for, particularly if you are returning lower than ideal grads on the reservoir for the L to H check. There are two more non invasive checks you can do: resistance measurements for the coils of front damper stepper motors. I'll dig out the spec but iirc it's 12.8-13.2 ohms across the coils and lastly you can (in Techstream at least) monitor the ecu output to the damper stepper motors. With the Snap On scanner see if there are two fields called "front wheel step" and "rear wheel step" whilst parked they will have "8" in them. Now if you repeat your 16 step test you'll see these fields step from 1 through 15 with each brake push. When driving with the monitor/Techstream connected you can observe the ecu commands to the front and rear damping circuits. If all this checks out then you've pretty much exhausted all diagnostic options and be confident that new globes isn't wasted money.

 

[camino70]

Honestly the work to install spacers is identical to installing new springs too so I'd recommend doing new AHC coils (about $200) and spacers ($50-60) at the same time if you're paying someone.

I recently swapped out my rear coils and wish I had done the spacers at the same time, I still need to get/insert spacers.

 

[PabloCruise]

I recently swapped out my rear coils and wish I had done the spacers at the same time, I still need to get/insert spacers.

What coils did you install? OEM? King? Other?

 

[camino70]

OEM 48231-6A740 and 48231-6A730

 

[WestTX28]

I've been meaning to check my pressure for a while but this thread motivated me to get it done. At 180K miles and having never been adjusted (other than 2 fluid changes since new) my '06 had a MPa of 7.3 front / 6.7 rear. So per PADDO I should need 2 turns to get 6.9 front.

Tightening the torsion bars (turning the bolts clockwise) lowers the front pressure 0.2MPa per turn on both bolts;

I did 1 turn at a time and checked. 1st turn dropped the front to 7.1. 2nd turn dropped the front to 6.9 and put the rear at 6.4.
PADDO knows his stuff. My LC rides like a dream and I know it's cussed here but I like having AHC.

 

[kmr12345]

Okay My ride is much better than where I started but still not what I would like. The rear is soft and the front is still pretty hard so I am going to change the front globes. What is the best value going right now? Oem or aftermarket. I have seen where good deals have come and gone was just looking to see what the best bet was going on right now. Thanks Again

 

[dwh13]

I know I’m piggybacking on an old thread, but I just got the Carsoft TYT II to get my neutral pressures right. When going from L to N, the front pressure reading gradually climbs to 6.6, then immediately falls to 2.5 and stays there. Should I assume the pressure is 6.6 or 2.5? This is with new globes, FWIW. Rears are reading a consistent 5.7.

 

[PADDO]

I know I’m piggybacking on an old thread, but I just got the Carsoft TYT II to get my neutral pressures right. When going from L to N, the front pressure reading gradually climbs to 6.6, then immediately falls to 2.5 and stays there. Should I assume the pressure is 6.6 or 2.5? This is with new globes, FWIW. Rears are reading a consistent 5.7.

A front pressure of 2.5 is very unlikely unless you’ve deliberately worked at it. 6.6F and 5.7R is certainly plausible, have you been adjusting TBs and what’s your rear coil/spacer situation (rear seats in/out) and overall front/rear heights? These factors all add to the bigger picture.
Thing is you just don’t really see nice low values without some intervention. Maybe you’ve lucked in but I’ve seen enough readings that have been obvious random outliers or suspect that I now augment Techstream with a pressure gauge which is a nice validation. On my own system Techstream values are 1.0MPa (FSM says expect approximately 1.2MPa) higher than actual pressure at the front dampers where you want 5.7 (825psi).

 

[dwh13]

A front pressure of 2.5 is very unlikely unless you’ve deliberately worked at it. 6.6F and 5.7R is certainly plausible, have you been adjusting TBs and what’s your rear coil/spacer situation (rear seats in/out) and overall front/rear heights? These factors all add to the bigger picture.
Thing is you just don’t really see nice low values without some intervention. Maybe you’ve lucked in but I’ve seen enough readings that have been obvious random outliers or suspect that I now augment Techstream with a pressure gauge which is a nice validation. On my own system Techstream values are 1.0MPa (FSM says expect approximately 1.2MPa) higher than actual pressure at the front dampers where you want 5.7 (825psi).

Everything is bone stock except it’s only got one of the third row seats. No spacers, original coils. I gave the TBs 3 blind CW turns a few months back to try and fix the ride pre-globe replacement.

Here’s a video of what I’m seeing when going from L to N:

 

[dwh13]

Update: after toying around with it some more this weekend, I realized that the AHC won’t move into N with the Carsoft TYT hooked up. It will try for about 60 seconds (you can hear the height accumulator whirring), but the truck won’t actually move. The pressures build to around 5.0, then the AHC light reverts to L. At first I thought the AHC pump was getting overheated, so I put it in L this morning, and then tried to raise it with the Carsoft plugged in this afternoon, to the same result. Everything works fine when Carsoft is not plugged in. Any ideas what I’m doing wrong?

 

[ibrahim83]

I will try the 16 step test thanks for the help. The lx has 103,000 miles. I cant really tell a difference between comfort and sport and the fluid didn't seem bubbly at all it had the same constancy as the new stuff or maybe a little thicker just a total different color.

Pardon my ignorance, but how and what is the 16 step test i keep hearing about?

 

[PADDO]

Pardon my ignorance, but how and what is the 16 step test i keep hearing about?

Step 4.

 

[ibrahim83]

Step 4.

Thank you!

 

[dwh13]

Update: after toying around with it some more this weekend, I realized that the AHC won’t move into N with the Carsoft TYT hooked up. It will try for about 60 seconds (you can hear the height accumulator whirring), but the truck won’t actually move. The pressures build to around 5.0, then the AHC light reverts to L. At first I thought the AHC pump was getting overheated, so I put it in L this morning, and then tried to raise it with the Carsoft plugged in this afternoon, to the same result. Everything works fine when Carsoft is not plugged in. Any ideas what I’m doing wrong?

In case anyone else has the same issue in the future, my AHC pump died while testing the pressures, unrelated to the Carsoft. I replaced the pump and just tried the Carsoft again, and got good solid readings.

 

[PADDO]

In case anyone else has the same issue in the future, my AHC pump died while testing the pressures, unrelated to the Carsoft. I replaced the pump and just tried the Carsoft again, and got good solid readings.

Was it the motor that failed or just the pump's filter screens blocked with sludge and o ring crud?

 

[dwh13]

Was it the motor that failed or just the pump's filter screens blocked with sludge and o ring crud?

I'm not sure, my trusty indy shop diagnosed it as a bad pump motor and through a weird series of events replaced it for free. But I've got a question for you - I just went outside to try reading my pressures again. Readings the first time of 8.8 Mpa (front) and 7 Mpa (rear). Cranked clockwise 5 times and tested again, got it down to 7.8 and 6.6 respectively as expected. Cranked another 5 times, tested, and it took a little longer to get to Neutral, and read pressures of 2.7 (front) and 6.7 (rear). Got a DTC of continuous pump pressure - did I ruin my pump again? There was about 10 minutes between each cycle of pressure testing, maybe it just temporarily overheated?

 

[PADDO]

These pumps are very solid and it’s not likely you’ve ruined it at all. You should be able to do multiple cycles without any issues. I strongly suspect you’re just seeing a spurious reading due to timing miscycling as the front leveling solenoid switches - I’ve seen it happen many times. Clear any codes and run it again.

 

[dwh13]

These pumps are very solid and it’s not likely you’ve ruined it at all. You should be able to do multiple cycles without any issues. I strongly suspect you’re just seeing a spurious reading due to timing miscycling as the front leveling solenoid switches - I’ve seen it happen many times. Clear any codes and run it again.

That’s a huge relief - thank you as always! FWIW, the ride was already pretty good, but after adjusting the pressures, it’s finally got that “magic carpet” ride I keep hearing about. Thank you for all your input to this thread!