AHC won't go up or down (1 Viewer)

[Ramathorn15]

I've spent the last few hours searching with no luck. I really hope someone here can help.

My LX470 refuses to go into H or L. It is stuck in N and will only flash twice when you push H or L and not do anything. Its the same as when the doors are open and you to adjust it or if you're going to fast and try to go up or down. The off light does not come on at all unless you push the off button.

Ive hooked it up to techstream and all my sensor are reading the proper height and are changing when put my weight on the sensors side of the vehicle.

I jumped the pump to see if maybe it was dead, and it still works.

It worked completely normally yesterday. The only thing I can thing of is I recently installed the Slee override and it was working perfectly. I taped it up and mounted it between the metal and plastic kick panels below the steering wheel since I didn't have factory button space, the wires were not long enough, and I didn't anticipate needing to switch it on/off.

Anyway, after the AHC quit working today, I reached up between the panels and noticed that it had shifted. I wonder if maybe one of the prongs on the board got exposed and shorted on the metal kick panel.

If it did, it must have messed up the AHC controller module and made the vehicle think its going to fast to change height.


Someone please help! I wonder how hard it is to get ahold of AHC controller module since so many people go to a standard suspension.

 

[Traskew3]

Can u take the AHC switch out and rewire it back to stock?

 

[Ramathorn15]

Can u take the AHC switch out and rewire it back to stock?

I tried that. It's back to stock now and doing the same thing.

 

[Traskew3]

Ugh!!, Call Slee on Monday I guess. Good luck and keep us posted. I thought about getting that switch but was going to have ACC in ATL install it... Maybe not...

 

[bucfl]

Just curious...but is it possible to reset the system by disconnecting the battery?

 

[Ramathorn15]

Ugh!!, Call Slee on Monday I guess. Good luck and keep us posted. I thought about getting that switch but was going to have ACC in ATL install it... Maybe not...

I can't say for certain if it's the override or not that caused this issue.

I will complain that it's not a very easily mountable chip. There's really no where to put it if you don't have any black switches from the factory. It's also kind of annoying there's not potting (epoxy) material or casing to keep it from shorting against a peice of metal.

 

[Ramathorn15]

Just curious...but is it possible to reset the system by disconnecting the battery?

I unplugged the batter for about 15 min earlier with no luck. I put it all back together (minus the override) and I'm leaving the negative terminal off for the night to see if it will reset overnight

 

[PADDO]

Sounds like there's the possibility that the +12v for the overrides' indicator light shorted on to the wheel speed sensor inputs to the ECU, frying it. If you've normalized everything I'd check fuses, check AHC DTCs and pull the 20A AHC IG fuse to power the ECU down. If the AHC ECU was spiked with +12vdc on to the wrong terminals there is a good chance it's dead, but hopefully it's just locked up and pulling its 20A fuse will clear it. If it won't work after you've tried pulling its power it might be worth trying to drive it in manually.

 

[Ramathorn15]

Sounds like there's the possibility that the +12v for the overrides' indicator light shorted on to the wheel speed sensor inputs to the ECU, frying it. If you've normalized everything I'd check fuses, check AHC DTCs and pull the 20A AHC IG fuse to power the ECU down. If the AHC ECU was spiked with +12vdc on to the wrong terminals there is a good chance it's dead, but hopefully it's just locked up and pulling its 20A fuse will clear it. If it won't work after you've tried pulling its power it might be worth trying to drive it in manually.

You're going to have to go a bit slower for me haha. What are the AHC DTCs?

I pulled the 20amp and 15 amp fuses (Both labeled AHC) under the dash.

I pulled the 50 amp under the hood too. They all look good and are pushing 12v on either both sides.

What do you mean by driving it manually? And how does one do that?

Thanks!

 

[PADDO]

AHC DTCs = trouble codes, C17xx. Go into Techstream and bring up the AHC page and one option is to view the trouble codes. Or better, just go into the AHC data list page and one of the fields says how many, if any, DTCs are present. Whilst in this page operate the up/down switch and see if it's status changes. Look to see if the main relay is on.
You can do an active test by shorting Ts and E1 in dlc1, then with the comfort switch at comfort start the engine and push the down switch 5 times < 5 seconds which will put you into the active test mode (flashing OFF light) and you can manually raise or lower front and rear if things are working normally.
Have you confirmed all the connectors to the ECU are secure? Nothing loose or not fully seated?
Edit: Probablly best to follow the fundamentals:
Check power sources are good, connectors seated, mod correctly removed and wiring normalized
The system isn't in an inhibited mode (i.e. Door open, brake pedal on)
The AHC indicator lights are functioning
Any DTCs present
Attemp the active test for manual height control
Perform the AHC ECU signal input test in Techstream

 

[Ramathorn15]

AHC DTCs = trouble codes, C17xx. Go into Techstream and bring up the AHC page and one option is to view the trouble codes. Or better, just go into the AHC data list page and one of the fields says how many, if any, DTCs are present. Whilst in this page operate the up/down switch and see if it's status changes. Look to see if the main relay is on.
You can do an active test by shorting Ts and E1 in dlc1, then with the comfort switch at comfort start the engine and push the down switch 5 times < 5 seconds which will put you into the active test mode (flashing OFF light) and you can manually raise or lower front and rear if things are working normally.
Have you confirmed all the connectors to the ECU are secure? Nothing loose or not fully seated?
Edit: Probablly best to follow the fundamentals:
Check power sources are good, connectors seated, mod correctly removed and wiring normalized
The system isn't in an inhibited mode (i.e. Door open, brake pedal on)
The AHC indicator lights are functioning
Any DTCs present
Attemp the active test for manual height control
Perform the AHC ECU signal input test in Techstream

Thanks for your help!

Techstream says I have 5 error codes. Unfortunately, it won't let me read them. I get an error each time I try.

I did every option in the active test and everything moved, or clicked. I couldn't hear/feel the rear gate switch do anything but I have a feeling that for dampening?

The truck will self level with no issues.

The only thing I can think of is the CPU for the AHC.

Here's my techstream screenshot in case you might see something off other than the 5 codes.

Do you know if someone who removed AHC can remove their computer without causing issues elsewhere with the vehicle?

I'd really rather not spend 2k+ from the dealer for a new one if people are rolling around with ones acting as paper weights

 

[PADDO]

Can you open the trouble code page? The top blue tab on the left, the codes should be listed there. Make a note of them and then clear them with the little engine/eraser symbol towards the bottom of the screen. It will ask for confirmation etc. If that doesn't work try a manual clear: ignition off, short Tc and E1 in dlc1, ignition on and push brake pedal 9 times in less than 3 seconds. IG off, remove short. Hopefully one of these methods works, but I've had a DTC C1743 that wouldn't clear either way and it wasn't until I pulled the 20A AHC IG fuse the ECU recovered itself.
Nothing really jumps off your screen shot as being out of whack, pressure sensor fields didn't all populate but that happens.
The rear gate valve is the one that connects/disconnects your rear wheels' hydraulically. It's probably fine and not a concern at the moment.
You can install someone's pre loved AHC ECU if they've done a delete without it introducing any new issues for them -beyond not having the designed inputs to vgrs, ABS/VSC ECUs.

 

[Ramathorn15]

Can you open the trouble code page? The top blue tab on the left, the codes should be listed there. Make a note of them and then clear them with the little engine/eraser symbol towards the bottom of the screen. It will ask for confirmation etc. If that doesn't work try a manual clear: ignition off, short Tc and E1 in dlc1, ignition on and push brake pedal 9 times in less than 3 seconds. IG off, remove short. Hopefully one of these methods works, but I've had a DTC C1743 that wouldn't clear either way and it wasn't until I pulled the 20A AHC IG fuse the ECU recovered itself.
Nothing really jumps off your screen shot as being out of whack, pressure sensor fields didn't all populate but that happens.
The rear gate valve is the one that connects/disconnects your rear wheels' hydraulically. It's probably fine and not a concern at the moment.
You can install someone's pre loved AHC ECU if they've done a delete without it introducing any new issues for them -beyond not having the designed inputs to vgrs, ABS/VSC ECUs.

Dude! You are seriously a life saver. I can't thank you enough.

My techstream doesn't let me read the codes for some reason. I constantly get an error. I assume its probably my crappy Amazon cable or software or the fact that I did a bunch of stuff to get it to work on my win 7 64-bit laptop.

Anyway, I jumped straight to shorting Tc and E1 to do a reset and it worked!!

Thank you so much man! I was about to buy the only AHC ECU on ebay for nearly $300!

 

[PADDO]

So all good now? Uppy and downy working like they should? If so then I reckon your ECU got some inadvertent electro shock therapy that blew it's little mind. Keep the $300 for beer coupons - after you buy a $2 roll of insulating tape or a little e projects hobby box and redo the override

 

[Ramathorn15]

So all good now? Uppy and downy working like they should? If so then I reckon your ECU got some inadvertent electro shock therapy that blew it's little mind. Keep the $300 for beer coupons - after you buy a $2 roll of insulating tape or a little e projects hobby box and redo the override

It is all good! Thanks again! Definitely going to make sure its better insulated when I put it back in! I thought wrapping it in electrical tape would suffice but I think being that close to an HVAC tube softened up the tape and caused the short.

 

[Gatorlx470]

Awesome News!!! Great Help Paddo!!

 

[Ramathorn15]

Paddo is like the AHC God. I did lots and lots of research on the AHC before deciding between the LC and the LX. Paddos post were always the most informative.

 

[trizzo]

Paddo is like the AHC God. I did lots and lots of research on the AHC before deciding between the LC and the LX. Paddos post were always the most informative.

he needs a custom license plate - DR AHC

 

[LXstatic]

Dude! You are seriously a life saver. I can't thank you enough.

My techstream doesn't let me read the codes for some reason. I constantly get an error. I assume its probably my crappy Amazon cable or software or the fact that I did a bunch of stuff to get it to work on my win 7 64-bit laptop.

Anyway, I jumped straight to shorting Tc and E1 to do a reset and it worked!!

Thank you so much man! I was about to buy the only AHC ECU on ebay for nearly $300!

Can you tell me what this Tc and E1 are, I am having the same trouble with my AHC Override. I installed it yesterday and I'm pretty pissed about it...

 

[Ramathorn15]

Can you tell me what this Tc and E1 are, I am having the same trouble with my AHC Override. I installed it yesterday and I'm pretty pissed about it...

Yeah. Look under your hood. There is a small box that looks almost like fuse box on the passenger side fender. Take the cap off and you will see a bunch of holes and the cap will tell you which hole is which. Then follow PADO's instructions on shorting/brake pedal tapping.

Should work after that hopefully.