Thread: PWM Fault Code.

A number of things have crossed my mind (probably all wrong, but here goes)....
Have you cleared the faults. The PWM thing could be old from when the ECU was changed.
Have you closed all the doors to allow your compressor to kick in?
Have you measured the resistance of the rear outlet valve coil with the ABS module disconnected? The resistance values are in the manual.
It wouldn’t hurt to take it for a drive.
Just a warning, I’m no expert, but have played around with these things in the past. Good luck.

There is definitely an issue with swapping SLABS and this PWM signal.

On my 2000 V8, when I tried 3 different other SLABS (from 2003 V8 models, 1 with SLS, 2 without) all 3 gave PWM codes 14-2. However when I swap back in my original 2000 SLABS unit with SLS, I get no PWM code.

I couldn't find any information other than "SLABS are able to be swapped, no problem" -- so it remains a mystery to me. In my case I could confirm there was no PWM issue because with 1 of my 4 SLABS ECU's, there is no issue and car works perfectly without warning lights.

IMG_1770.jpg

Wasn't sure if you had Diesel but it does say "chk circuit continuity C0504-10 TO C0658-32" (SP wire which I think is silver purple)

PWM.gif

Some other ideas, again all v8 below...

Engine ECU 0637-17 - PWM output to SLABS CO504-10 (White-Silver)
Engine ECU 0637-34 - PWM input- Rough Road Signal to SLABS C0504-4 (Red-Green wire
Engine ECU 0636-29 - PWM HDC Output (Silver-Purple) to C)504 - 10 on SLABS


The HDC signal output from the ECM is via pin 29 of connector C0636


ECM. —>. —> —> —>—>— > SLABS

C0637-34 (RG) —>—>—>—>—> C0504-4
CO636-29 (SP). —> >—>. —>—> 0504-10
also CHK CONNECTOR C0203-6 C0449-6

C0637-17 (WS) —>—>—> —>—>—> C0655-10
Engine Control Module (ECM)
The ECM provides an engine speed signal on a WS wire to header C0291. From the header
the signal is passed on a WS wire to the instrument pack for tachometer operation. A second
WS wire is connected from the header to the SLABS ECU pin C0655-10.

The only circuit that can trigger this fault code with other SLABS while with the original it's OK is the input to SLABS C0504 -10 (engine data, torque, engine type, gearbox type, TPS) and i'm 100% certain the problem is not with the circuit but with a missmatch between softwares so quit chasing wiring issues cos you struggle in vain, i've seen this happenning on most V8s and on Td5 only when a SLABS removed from a V8 was fitted, it doesnt happen when ECUs are swapped between Td5s. I can't try as i dont have a V8 ECU within reach but there is a programming option in the SLABS where the vehicle's VIN can be inserted, the only tool apparently capable of that is Foxwell(or other more expensive and advanced main dealer tools), i have Foxwell 510 Elite(same as 530 soft) but as i said i can't try to confirm, the gist is that it seems that for the V8 is important for the VIN stored in the ECM to match with the VIN stored in SLABS to work, unfortunately nanocom doesnt cover that, here's a snapshot from SLABS ECU info shown by Foxwell but i'm not 100% certain if it has the capacity to introduce other VIN there . What you can try is to run a "reset addaptive values" for the ECM with nanocom - utility, maybe it recognises the new SLABS too then... not many chances but worth a try

Yes the vehicle is a V8. I have spent one and half days checking every input and output to and from the SLABS for the suspension. I had to work out what I was doing and how it was all wired etc first.

The PWM fault is only there when all the ABS plugs are connected.

The levels for the Suspension cannot be changed by Nanocom saying the levels I am trying to input are too high even a 1. When I try and store the new levels it says that it cannot communicate with the ECU.

The Nanocom cannot raise either side during that test although the compressor comes on for its own test. Apart from that every input and output seem correct to me. I do get a reading from the EMU to the SLABS that is pulsing but reads steady on AC volts scale not sure what is right or wrong there.

My solution at this point is to try and get the ABS working and then set up a manual raise and lower switch using the vehicle compressor. If I cannot get the ABS to work then I need another SLABS. But how to get the VIN into the SLABS ECU is a question yet to be solved. I'll also try the reset adaptive values. Don't remember seeing this on the Nanocom but I'll look again.

Thanks Guys. These problems always cause me to spend hours and hours chasing my tail. But I don't like them beating me.

Originally Posted by Robflocar

Faults were always shuttle valves and level sensor faults.

maybe I've missed something , but wouldn't you just repair / replace these, rather than replacing components that weren't listed ?

Originally Posted by discorevy

maybe I've missed something , but wouldn't you just repair / replace these, rather than replacing components that weren't listed ?

Yes sorry I didn't include that the air suspension didn't work either.

Car came with 3 amigos and after a couple of years of putting up with it I was given another SLABS ECU.

I have since discovered that the SLABS needs VIN, engine type, gearbox type, etc. The NANOCOM will not even display a lot of what is in the SLABS much less allow it to be changed.

I need details of what OBD2 I should buy, for a reasonable price, that will do this re-programing. Many people talk on the web of clearing fault codes etc but no one I have found, other than sierrafery, has spoken about re-progamming this stuff in a SLABS and given details on what to use. I don't want to spend money on another OBD2 that doesn't do what is needed.

I looked up the Foxwell site and became confused and not yet prepared to commit without knowing whether these codes can be changed.

May be my original SLABS is also not the original but someone elses attempt to fix the problem. Back to manually getting air into the airbags, and no ABS for the time being I guess.

Is there any reason you can't fit the original slabs ?

I can confirm now that Foxwell NT530 can modify the VIN but i can't confirm if this will fix the issue or not