(Fairly urgent) LX470 AHC (frt riding bumpstop) no AHC dash light or service lights (1 Viewer)

[shelbyk7]

Do any of you know whether or not the AHS switch on center console could affect the whole system like what I have? The switch only lights up the bottom button (up and down AHS height) (pic attached)

Could that switch being out cause these problems?

 

[ktmracer01]

It's likely there is just a bulb burned out in the switch. If you have power to the lower portion of the switch, you should have power to the upper portion. Easy way to find out...pull the other bulb and see if it's burned out.

Since you mentioned the 'OFF' button isn't doing anything, there's a chance it could be the switch. But, you could be barking up a tree if you don't have Techstream. So, focus on getting that operational.

edit: the AHC will not operate if any of the doors are 'Open.' Make sure you're not inadvertently preventing the system from working properly.

 

[J1000]

Off is for when the vehicle is lifted off the ground but the key is still on. It doesn't do anything otherwise.

 

[shelbyk7]

It's likely there is just a bulb burned out in the switch. If you have power to the lower portion of the switch, you should have power to the upper portion. Easy way to find out...pull the other bulb and see if it's burned out.

Since you mentioned the 'OFF' button isn't doing anything, there's a chance it could be the switch. But, you could be barking up a tree if you don't have Techstream. So, focus on getting that operational.

edit: the AHC will not operate if any of the doors are 'Open.' Make sure you're not inadvertently preventing the system from working properly.

Okay I’ll try the bulb switch

However, with the AHS not showing on the dash, I checked the ecu as well for any plugs that could have been removed from the AHS ecu and everything is still plugged in?

That’s what I’m trying to figure out is what all could cause the dash to NOT display AHC height, nor do I get blinking “AHS” off when pushing button

Really lost being that the Techstream won’t connect to the AHC


I was borrowing a windows computer and had to give it back, I ordered a new windows laptop and will have it Wednesday and will try to connect again

 

[uHu]

With no AHC in TechStream and no AHC lights in the instrument panel, I would guess that either the AHC ECU is missing power or earth, or that the ECU doesn't know that the engine is running. There is an Alternator input on the AHC ECU, which I suppose is for the purpose of detecting that the engine is running. The plug on the alternator is known for sometimes malfunctioning, either corrosion or lost spring force of the plug terminals.

 

[shelbyk7]

Have the new laptop w Techstream

Tried again and getting same errors


Took off alternator connector and it was clean and tight , pushed it back on

Where exactly can I test the ground and power for AHC ecu?

 

[uHu]

The FSM lists the voltages expected on each pin on the plugs, and lotsa other diagnosis info.

 

[shelbyk7]

I have taken the dash off to test ecu and the
AHC relay (the one attached to the ecu)

So the test I performed (pic Attached)

When I tested with meter, terminals 2&4 I got OL, terminals 1& 3 I got 62ohms but my meter wasn’t beeping for continuity?

Can you have continuity while have 62ohms of resistance?

On 2nd test I applied 12v to 1&3 Which made it click and closed 2&4 which gave me continuity @ 0.16 ohms

So it looks like maybe the first test with 1&3 not being in continuity is the problem?

Could the relay just barely be hanging on causing it to still able to close when I attach 12v direct to 1&3?


Picture also showing the terminals of the relay, look to have some wear on them, or is that normal?

 

[medtro]

When I tested with meter, terminals 2&4 I got OL, terminals 1& 3 I got 62ohms but my meter wasn’t beeping for continuity?

Can you have continuity while have 62ohms of resistance?

Yes, 62 ohms is continuity. The table you posted calls for 62 ohms too.

 

[shelbyk7]

Yes, 62 ohms is continuity. The table you posted calls for 62 ohms too.

So what would cause my meter to not “beep” for continuity?

 

[medtro]

So what would cause my meter to not “beep” for continuity?

No ideas. May be defective meter? May be you missed the beep? Did you measure it more than once? Will your meter beep above X ohm resistance? How does your meter define continuity? 62 ohms is no where close to open circuit.

 

[shelbyk7]

No ideas. May be defective meter? May be you missed the beep? Did you measure it more than once? Will your meter beep above X ohm resistance? How does your meter define continuity? 62 ohms is no where close to open circuit.

I will check it out

 

[shelbyk7]

Okay, was trying to figure out why some manual tests wouldn’t work, one of the tests for AHC ecu and AHC main relay (connected to AHC ecu) was to connect with jumper from TS and CG of DLC3. That’s when I noticed there wasn’t a pin in that Slot , did some research and still can’t figure out what’s going on and if that’s possibly all of my problems?

I found the actual TS by examining the location of TS on the AHC ECU and noted the wire color (white) and then went to DLC3 and performed continuity test and it was correct

Pics attached

 

[medtro]

I will check it out

You would fail the 2nd test if there was no continuity in the first test.

 

[shelbyk7]

I have received the replacement AHC ECU

Will try to install today


I have a Tesla screen conversion , does the head unit have anything at all to do with AHC ecu? do they communicate at all? I wouldn’t think so but wanted to check in case it could be reason for the original AHC ecu failure?

 

[shelbyk7]

Update:

FIXED!

AHC ecu was fried, replaced it and all worked like new


Thanks for all the help!

 

[shelbyk7]

Okay, trying to set baseline pressures (adjust tbar and level front shocks)

What are the ideal pressures at LO N HI?

Here’s my pressure for N and Hi

Why does N show no pressure?

 

[uHu]

Congratulations. Good progress.
For pressures, you have to do the reading the right way. This is all described in several threads in here, but in simple terms:
There are no pressure gauges/sensors in the AHC system except for the one at the pump. This one is used by TechStream in an inventive way by reading pressure just at the right time and condition. The only way to get anything useful out of the TechStream AHC front and rear pressures, is to move the ahc to low, let it rest for 30 sec, and then raise it to N. Then, after reaching N height and stabilizing there, you can read pressures that are quite close to the real globe/shock pressures for the front and the rear ahc circuits.
These numbers, together with real life height measurements, can be used to dial in the suspension system and balance the steel spring force (coils and TBs) and the gas spring force (globes).

 

[shelbyk7]

Congratulations. Good progress.
For pressures, you have to do the reading the right way. This is all described in several threads in here, but in simple terms:
There are no pressure gauges/sensors in the AHC system except for the one at the pump. This one is used by TechStream in an inventive way by reading pressure just at the right time and condition. The only way to get anything useful out of the TechStream AHC front and rear pressures, is to move the ahc to low, let it rest for 30 sec, and then raise it to N. Then, after reaching N height and stabilizing there, you can read pressures that are quite close to the real globe/shock pressures for the front and the rear ahc circuits.
These numbers, together with real life height measurements, can be used to dial in the suspension system and balance the steel spring force (coils and TBs) and the gas spring force (globes).

Thank you, that’s what I was missing, going low first