Suspension problem even after replacing almost everything

[uHu]

I just hooked up the teachstream cable and got some readings by moving the suspension from low to N to high. Pls see if this makes sense as I'm not familiar with these readings.

1). Switch Low -> N (Front - 7.3, Rear 5.5, accumulators 10.4)
2). Switch N -> High (Front - 9.5, Rear 3.2, accumulators 10.3)
3). Switch High -> N (Front - 9.6, Rear 3.3, accumulators 10.3)
4). Switch N -> Low (Front - 9.6, Rear 3.2, accumulators 10.3)
5). Switch Low -> N (Front - 7.4, Rear 5.2, accumulators 10.3)

At the N position I noticed that the front angle sensor FL was 0.0 and FR - 0.4 and Rear - 0.5.

No DTC error for AHC. Only have 2 DTC errors under Immobiliser - B2780, and another under tilt/telescopic - B2602 (key unlock warning switch).

Any help is much appreciated. Thanks.

The important value is the one at level N, after a move up from Lo. The pressures are all measured at the pump, and showing the pressure there at the exact time when the front or rear reached it's height. So, the pressure measured when it reached Lo is not really of any use, but it is normally much lower than what you report here. And that the rear press after going to Hi is lower than at N is puzzling.
Always read the pressure a while after the suspension has reached the N level, like 20 secs after, to be sure.

So, at step 1 and 5 (I numbered the lines for you), the front is 7.3 to 7.4, which is at the upper bracket of the specs. You ought to tighten the TBs a bit, but this issue should not lead to the situation you describe as a very hard suspension.

The rear pressure is too low (5.6 to 6.7), which leads me to think that your rear height is too low. There is a procedure in the FSM for checking the height -- it is not difficult to do, but it takes a bit of consentration to understand, and to find the points to measure from.

If you actually got new globes (easy to check the # of graduations), I tend to suspect the actuators, like cruiser03 describes in another thread. If you go through the other input tests of the ahc system, and all is ok, there is in the end not much else to suspect.

 

[Vampo]

The important value is the one at level N, after a move up from Lo. The pressures are all measured at the pump, and showing the pressure there at the exact time when the front or rear reached it's height. So, the pressure measured when it reached Lo is not really of any use, but it is normally much lower than what you report here. And that the rear press after going to Hi is lower than at N is puzzling.
Always read the pressure a while after the suspension has reached the N level, like 20 secs after, to be sure.

So, at step 1 and 5 (I numbered the lines for you), the front is 7.3 to 7.4, which is at the upper bracket of the specs. You ought to tighten the TBs a bit, but this issue should not lead to the situation you describe as a very hard suspension.

The rear pressure is too low (5.6 to 6.7), which leads me to think that your rear height is too low. There is a procedure in the FSM for checking the height -- it is not difficult to do, but it takes a bit of consentration to understand, and to find the points to measure from.

If you actually got new globes (easy to check the # of graduations), I tend to suspect the actuators, like cruiser03 describes in another thread. If you go through the other input tests of the ahc system, and all is ok, there is in the end not much else to suspect.

Hi thanks for your input. I will re measure the pressure today. Is there some way I can clean/service the actuators? I really don't want to spend more money on this issue unless absolutely necessary.

I also feel that the inside suspension comfort selector switch is not responding. every setting feels the same.

 

[ElHefe]

Hi thanks for your input. I will re measure the pressure today. Is there some way I can clean/service the actuators? I really don't want to spend more money on this issue unless absolutely necessary.

I also feel that the inside suspension comfort selector switch is not responding. every setting feels the same.

Make sure your contacts are clean on the switch, they're at the bottom once you remove it. Not too hard for moisture to get into the board.

 

[Vampo]

Make sure your contacts are clean on the switch, they're at the bottom once you remove it. Not too hard for moisture to get into the board.

I just measured the neutral pressure again (leaving about 30 sec to stabilize after each change). The readings are very similar

1). L to N (front - 2.7, rear - 5.7) (this is the first reading after the vehicle was being parked for 8 hours, I moved it to L from N and took this reading)
2). N to H (front 9.7, rear - 6.7)
3). N to L (front 9.7, rear - 6.7)
4). L - N (front 7.3, rear - 6.2) (this I re checked after about 2 minutes, and the same values were shown)

I will remove the switch and clean it in a while as well.

 

[Vampo]

Hook up your TechStream and get some readings and check for DTCs. Focus on AVS related elements in your system, did it ever respond to comfort switch settings? and attempt the 16 step AHC damping test to see if you can progressively feel the damping increase through the range. It takes 10 minutes to pop out the damping selector switch and clean the sliders in it, maybe it's gunked up after the last coffee spill?, you only have about 9v through it so it's easy to interfere with that signal. Try resetting the AHC computer by pulling the fuse in the driver side kick panel. Pull and clean all the damping force valve connectors, pull and clean the connectors at your AHC module. If there is an AHC/AVS computer comms problem it should throw codes but possible not. Check your damping force actuator common ground is good, it's pin 2 iirc of each damper connector.


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Hi Paddo,


Would you know of any method to clean the actuators ? (possibly a chemical that might flush the units of any dirty etc). Thanks.

 

[PADDO]

Hi Paddo,


Would you know of any method to clean the actuators ? (possibly a chemical that might flush the units of any dirty etc). Thanks.

No you can't run any cleaning chemical through them, please don't add anything other than toyota AHC fluid to the reservoir. Bleeding old fluid through each bleed point and replacing it with new is the way to go.
You just need to do the L to N raise to get initial neutral pressure readings, as uHu said, get the front pressure down, say 2 tightening turns on each TB bolt and re measure. Your rear neutral needs to be in the 5.6 to 6.7 range so make sure you are on level ground and get overall vehicle heights correct and see if the rear neutral pressure comes in spec with heights correct. Please confirm your globes are still serviceable by counting the number of grads on the reservoir between L and H. If neutral pressures are ok, globe charges ok, pump OP is good, ECU output is good and is being switched through the comfort selector switch and it is still stuck at or beyond the hardest comfort setting then you're probably looking at failed damping force actuators unfortunately. The comfort switch grounds two of the ECU terminals in an either/or/both open/both grounded to vary between softest and hardest comfort settings. If that switch is not making any contact, ie not grounding either/both terminals then this equates to the hardest setting so it's worth popping the switch and cleaning the slider contacts, it's quick and easy. There is a simple test you can do to manually step the damper actuators through their range. I would attempt that too to see if there is any control over the dampers, if not that again points to failed dampers if everything else checks out.


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[Vampo]

No you can't run any cleaning chemical through them, please don't add anything other than toyota AHC fluid to the reservoir. Bleeding old fluid through each bleed point and replacing it with new is the way to go.
You just need to do the L to N raise to get initial neutral pressure readings, as uHu said, get the front pressure down, say 2 tightening turns on each TB bolt and re measure. Your rear neutral needs to be in the 5.6 to 6.7 range so make sure you are on level ground and get overall vehicle heights correct and see if the rear neutral pressure comes in spec with heights correct. Please confirm your globes are still serviceable by counting the number of grads on the reservoir between L and H. If neutral pressures are ok, globe charges ok, pump OP is good, ECU output is good and is being switched through the comfort selector switch and it is still stuck at or beyond the hardest comfort setting then you're probably looking at failed damping force actuators unfortunately. The comfort switch grounds two of the ECU terminals in an either/or/both open/both grounded to vary between softest and hardest comfort settings. If that switch is not making any contact, ie not grounding either/both terminals then this equates to the hardest setting so it's worth popping the switch and cleaning the slider contacts, it's quick and easy. There is a simple test you can do to manually step the damper actuators through their range. I would attempt that too to see if there is any control over the dampers, if not that again points to failed dampers if everything else checks out.


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First thank you and all the other members who provided suggestions and information for my problem. I'm just so frustrated about this issue.

Over the weekend I tried a few tests, the results are below

Neutral Pressure
After I adjusted the TBs I have managed to get the Front - 6.8 and Rear 5.6

Wheel height (are these heights within the range)
I changed the wheels to my friends original set of Bridgestone 275/60/18
Front height hub center to fender 19.5"
Rear height hub center to fender 20"

Selector switch
I removed it and cleaned it. When I switch between the 4 options, I can seen in techstream the damper switch 1 and damper switch 2 changing from Low - OFF,ON
Normal - ON,ON
Sports - ON,OFF
Sports2 - OFF,OFF

I tried the 16 step manual damper adjustment, but I had no idea whether it was working or not.. is there some way the damper setting can be seen while DLC3 is short circuited. As I have a Japanese Domestic version LC 2005 (Cygnus), my DLC3 doesn't have a Ts pin (pin 14), so I read on some forum that the short circuit should be between CG and Tc (pin 4 and Pin 13). I tried this and I believe the rig went into a test mode with most dashboard lights flashing.

I drove it around on a rutty road, and I just couldn't feel anything different. I'm not sure if I did the procedure right, can you pls confirm

I short circuited the DLC3
I pressed the brake pedal 8 times within 3 seconds
I switched the key to OFF, then started the engine and depressed the brake 1 time and drove the rig
I switched the key to OFF, and again started the engine and depressed the brake 16 times and drove the rig

Is this process right? BTW is 1 or 16 the hard suspension setting?

 

[PADDO]

Your neutral pressures are better, front is good and rear is lower end of range, any chance you have aftermarket coils or packers? At this stage I think we are past blaming neutral pressures for your lack of damping. Height at 19.5 and 20" is in line with expectations. There is a procedure (posted severla weeks ago under heading of "AHC fsm") to specifically measure between the axle c/l and suspension bolt centers which will give you heights down to the millimeter, but 19.5" and 20" hub c/l to fender is rough enough at this stage. Your selector switch is reporting correctly through techstream. Not sure about the damper test you did and any differences in JDM vehicles. I've attached the US market procedure were you short Ts and E1 of DLC1 (under the hood). 1 is softest 16 is hardest. I can't honestly detect 16 incremental steps of firmness, but if everything is working you will easily tell the difference between soft, harder and really firm. I know you replaced your 4x globes initially and now is a good time to confirm they are still serviceable by checking the number of grads between L and H. They could have failed due to contaminated fluid or a manufacturing defect. Check they are still functional, at 2 years old you should have maybe 11 or 12 grads at least, if 14 grads is/was new. Being aftermarket units do you know what their initial charge/volume ratio compared to OEM is, some vendors state they can tailor charge pressure to clients needs. If you can't get any damping response in the manual test then its another nail in the coffin for failed damper actuators. You could try running a can of fresh fluid through the system and set the damper switch to softest and hit some roughs to see if it frees anything up. Cheaper than $2k for damper actuators. Good luck.

 

[Vampo]

Your neutral pressures are better, front is good and rear is lower end of range, any chance you have aftermarket coils or packers? At this stage I think we are past blaming neutral pressures for your lack of damping. Height at 19.5 and 20" is in line with expectations. There is a procedure (posted severla weeks ago under heading of "AHC fsm") to specifically measure between the axle c/l and suspension bolt centers which will give you heights down to the millimeter, but 19.5" and 20" hub c/l to fender is rough enough at this stage. Your selector switch is reporting correctly through techstream. Not sure about the damper test you did and any differences in JDM vehicles. I've attached the US market procedure were you short Ts and E1 of DLC1 (under the hood). 1 is softest 16 is hardest. I can't honestly detect 16 incremental steps of firmness, but if everything is working you will easily tell the difference between soft, harder and really firm. I know you replaced your 4x globes initially and now is a good time to confirm they are still serviceable by checking the number of grads between L and H. They could have failed due to contaminated fluid or a manufacturing defect. Check they are still functional, at 2 years old you should have maybe 11 or 12 grads at least, if 14 grads is/was new. Being aftermarket units do you know what their initial charge/volume ratio compared to OEM is, some vendors state they can tailor charge pressure to clients needs. If you can't get any damping response in the manual test then its another nail in the coffin for failed damper actuators. You could try running a can of fresh fluid through the system and set the damper switch to softest and hit some roughs to see if it frees anything up. Cheaper than $2k for damper actuators. Good luck.

Thanks for the procedure doc. I wil try that again. I replaced the accumulators and shocks about 2 weeks ago with Toyota OEM parts. right now I get about 14 grads on the L to H AHC test.

 

[Vampo]

Ok this is what I did today. I short circuited the E1 and Ts pins in the DLC1 connector (as in the procedure - Thanks to PADDO). I connected my techstream to DLC3 and watched the front and rear wheel steps increase from 1 to 16 as I stepped on the brakes.

I drop the rig at step 16, which was extremely hard and bouncy. basically when you fall into a rut, it feels like there are no shock. Next I reset the actuators to 1 and drove. There is definitely a difference, but I still feel the level 1 should be much much more comfortable that what I get. (simply comparing my friends rig with mine).

I finally removed the short circuit and drove around with the techstream plugged in. whenever I changed the damper selector switch, I noticed the readings also changed. So again that confirms the switch + ECU is working together.

The actuators becoming hard also confirms that the ECU has some sort of control over the actuators.

I just don't want to bust more money in buying actuators as an experiment. Already replaced the accumulators and shocks with Toyota OEM 2 weeks ago.

Could it be that the actuators are not fully opening? Now I'm out of ideas, any suggestions anybody?

 

[kgrove]

Make sure your contacts are clean on the switch, they're at the bottom once you remove it. Not too hard for moisture to get into the board.

How do you remove the switch to clean the contacts? I don't want to start pulling and prying randomly and potentially break something.

 

[PADDO]

How do you remove the switch to clean the contacts? I don't want to start pulling and prying randomly and potentially break something.

It pops out easily, use a plastic trim tool or screw driver with tape on the blade tip. I've posted pictures of the internals that should come up with a search. To clean the contacts try a pencil eraser and then a q tip with rubbing alcohol.

 

[PADDO]

Here's what's inside the AHC switch

 

[kgrove]

That's perfect... Thanks much.

There was a little bit of buildup on my switch plus a little bit of white grease. I assume the grease is coming from the switch mechanisms above the electronics and the grease liquifying a bit in our super hot temperatures here, then running down into the electronics.

I cleaned the contacts and reinstalled... Can't really tell if it made a difference or not. I still can't really feel much difference between full comfort vs full sport modes. Maybe my butt just isn't sensitive enough! What situations have you all found that best demonstrate the difference between modes? Is there any time lag between changing the settings and when you can feel the difference?

 

[PADDO]

That's perfect... Thanks much.

There was a little bit of buildup on my switch plus a little bit of white grease. I assume the grease is coming from the switch mechanisms above the electronics and the grease liquifying a bit in our super hot temperatures here, then running down into the electronics.

I cleaned the contacts and reinstalled... Can't really tell if it made a difference or not. I still can't really feel much difference between full comfort vs full sport modes. Maybe my butt just isn't sensitive enough! What situations have you all found that best demonstrate the difference between modes? Is there any time lag between changing the settings and when you can feel the difference?

Check out post #30 above, you can manually step through settings whilst monitoring with tech stream. No time lag as you switch through settings while driving. Are your neutral pressures etc in spec? Tires P or LT and are your pressures close to factory recommended or pumped up rock hard?

 

[Wilsil]

Will cleaning these contacts help if the suspension-mode 1-4 doesn't make any difference?

 

[Vampo]

Hi,

Does anybody know what the damping force actuators voltages are to step it from 1 to 16 ? Thanks.

 

[SALTY METHODS]

This might be a stupid question but do AHC equipped LCs have torsion bars? Because if they do, maybe your torsion bars are cranked too much causing the stiff ride.

 

[Vampo]

Hi SoupGFX,

I tried that. If I reduce the load on my torsion bar any more, the neutral pressure goes out of the range. I.e. too much load on the accumulators.

 

[kgrove]

Check out post #30 above, you can manually step through settings whilst monitoring with tech stream. No time lag as you switch through settings while driving. Are your neutral pressures etc in spec? Tires P or LT and are your pressures close to factory recommended or pumped up rock hard?

Neutral pressures are fine - front 6.4 and rear 6.3 (barely on the low side). Tires are P at 35psi.

One oddity... I decided to replace the AHC fluids again thinking the previous fluid was so bad I didn't get it all flushed. When I tried to drain the accumulator (think that's the name - the cylinder shaped one between the two drivers side globes), nothing came out. The pressure in the accumulator was I think 10.4 the day before when I measured it, but no fluid drained - tried several times. Maybe a clogged hole... Unfortunately I ran out of time to investigate further and will have to get back to it in a couple days.