(Solved!) 2004 Lexus LX470 Nothing happens when AHC switch is operated? (1 Viewer)

[Chibu]

Got a 2004 Lexus LX470. Few weeks ago I got the AHC to function for the first time in like 10 years by replacing the 20amp AHC-IG fuse that was missing. The car went from empty shocks and bumpy ride straight to N position and is holding at N position, it drives fine, doesn't feel like a pogo stick or anything, everything is all good. So i'm a curious person by nature, i'm the guy that's always like "well what does this button do?" So i go to press the AHC switch just next to the gear selector. I press the up button and look at the AHC dash indicator, no change, no pump movement, nothing. I press the OFF button, no change, no movement. I turn the knob from comfort to sport, nothing. I turn it back to comfort, nothing. I (very very tenderly) mash the down and up buttons, no change in anything. Anyone know what the issue is here?? Here's a list of things that has been done:

During all this testing, I was the only person in the car (I weigh like 115 lbs), everything on the car is stock, no aftermarket bumpers or weight or anything, all doors were closed, car was in P position (without parking brake up) and brake pedal was never touched.
Checked the AHC dash lights (via turning key to ACC position) and all AHC dash lights (including OFF light) flash on as they should.
I checked fluid level in AHC reservoir, seems to be just below MIN line but not sure if that's the actual level or if that's just because the container is stained.
Connected the pump directly to the battery and it runs fine but of course no fluid came out of it for some reason.
Shorted Ts and E1 pins in DLC1 located at engine bay wall around the air filter housing and tried to put the AHC into test mode. Started the car, dash lights up like a christmas tree. (very tenderly) Mash the down button at least 5 times within 5 seconds of starting the car and still nothing.
Found the most level surface you could imagine, tried operating the AHC via the switch and still nothing.
Both front height sensors have been brought out and thoroughly cleaned and sprayed with electrical insulator and correctly replaced to their respective sides.
AHC ECU has been checked and works fine.
Brought out the switch and sprayed electrical insulator on the male and female electrical connectors to it and let it sit for 5 mins then coupled it back to it's original state and still nothing. Let it sit for a day and still nothing.

Honestly i'm at a total loss. The next thing would be to get an OBD-II dongle and hook up techstream (don't ask how i got techstream lol) but yeah that's not really an option as that's up to my dad who's not as enthusiastic as we men of culture :/

Any help or suggestions would be greatly appreciated. Tomorrow is the perfect day to work on this! Cheers!!

 

[Chibu]

Bump

 

[Zimruiser]

I have a similar problem with mine. I have a 2002 100 series Amazon TD. The difference is my AHC goes into up and down position and hold no problem. But the comfort control if I change from comfort to sport on each click I don't feel a change or any difference in the ride. Completely stock like yours.

So after doing similar testing to what you did I came to a conclusion. My vehicle is from the UK and from the history I have on it it was driven down by the cost and there is alot of salt and road grime/slate deposits on the underside of the vehicle. The rust on the underside is I would say on a scale from 1-10 about a 4. The shock covers are damaged and I wonder if all the grime is just getting in the wrong places and stopping it from working.

My AHC when I first got it worked on and off. As I used it more and more it worked better and better.

So this might be no help to you but what's the underside of your LX like? Maybe if you have the rust it might be prevent your shocks and AHC from functioning how it should. Just a thought

 

[Chibu]

Well at a glance the under is pretty clean, there's just dust on everything giving it a brown tint but no rust. All shocks were inspected a year ago and deemed okay except the front passenger shock which was leaking and replaced. I just don't know what the issue is. Like I said the AHC hasn't even been active on the car for at least 5 years because one of its fuses was missing but when I replaced that fuse the car went up to normal (although without any human input or switches operated) but now won't move at all.

 

[Zimruiser]

And a AHC flush. Maybe the inactivity for 10 years the AHC fluid has gone bad or separated. Not sure if this is possible.

 

[Chibu]

Yeah, definitely gotta do an AHC flush soon. That's the only thing other than Techstream I haven't done. I know it's easy but i'll probably just hold off on that.

 

[Zimruiser]

I feel your pain. Will be watching the thread for further development.

 

[medtro]

I press the up button and look at the AHC dash indicator, no change, no pump movement, nothing.

Did you have all the doors closed?

 

[Chibu]

Did you have all the doors closed?

"During all this testing, I was the only person in the car (I weigh like 115 lbs), everything on the car is stock, no aftermarket bumpers or weight or anything, all doors were closed, car was in P position (without parking brake up) and brake pedal was never touched."

Yeah man, all doors were closed. Including tail and liftgates and even bonnet for good measure.

 

[Chibu]

Another bump because i'm desperate

 

[suprarx7nut]

If there is no change in the lights in the dash when you press the up/down buttons then the buttons may be the problem.

Have you tested the physical switches in the center console to make sure they are plugged in and sending an electrical signal?

 

[Chibu]

Well I brought out the switch and made sure it was connected, but I didn't use a meter to check its plugs.

 

[Ramathorn15]

I'd start with the switch. Typically if there is a mechanical issue you'd still get a flashing light when you hit H or L and off would still work. No change in lights makes me think it's not getting a signal from the switch.

Possibly someone spilled something on the switch in the past fried it.

 

[Ramathorn15]

That may also explain why the fuse was blown.

 

[mudbutt]

Pretty sure it is the switch like it was for me. What you described is exactly the same as what happened to my 98 LX

 

[Chibu]

Pretty sure it is the switch like it was for me. What you described is exactly the same as what happened to my 98 LX

What did you do to fix the switch?

I'd start with the switch. Typically if there is a mechanical issue you'd still get a flashing light when you hit H or L and off would still work. No change in lights makes me think it's not getting a signal from the switch.

Possibly someone spilled something on the switch in the past fried it.

Will do. Highly likely someone spilled something on it as most of my siblings were young when the car was in its prime amount of usage. (circa 50-100 miles each day)

That may also explain why the fuse was blown.

Well actually that 20amp fuse was not blown. It was just not there. It was removed and never replaced for some reason. Probably someone clumsy had a go at it for a reason or another.

 

[LndXrsr]

Probably will just need a new switch or the wiring downstream from the switch has a short somewhere.

 

[Chibu]

Yeah, will check if I can get another switch from a local mechanic (had AHC switches last i saw him).

 

[mudbutt]

What did you do to fix the switch?

Will do. Highly likely someone spilled something on it as most of my siblings were young when the car was in its prime amount of usage. (circa 50-100 miles each day)

Well actually that 20amp fuse was not blown. It was just not there. It was removed and never replaced for some reason. Probably someone clumsy had a go at it for a reason or another.

Bought a used one on eBay for about $40.
There's a good number of them out there to try out.

 

[Chibu]

Thank you.