P38 traction/ABS problem

feyniriel · 2025-09-09T09:03:33+0100

A couple days ago while parking, TC and ABS lights came on and dash said traction failure. When restarting the car, lights were gone but upon driving the brake started crackling/vibrating as if ABS is engaged. This happens every time while braking.

Tried to see any faults with Nanocom but it doesn't connect with either ECU. It shows WABCO C and WABCO D (if I remember correctly), the D just says "can't establish connection with ECU" and C says nothing. If I press on anything, like faults or inputs, it will load for half a minute and show nothing! I'm not sure what this could mean, any ideas?

kermit_rr · 2025-09-09T09:10:53+0100

what year is it? have you checked the odb socket is clean and not green/corroded?
does it happen when you brake at a slow speed, high speed or both?

feyniriel · 2025-09-09T09:38:20+0100

kermit_rr said:
what year is it? have you checked the odb socket is clean and not green/corroded?
does it happen when you brake at a slow speed, high speed or both?

Forgot to specify, it's a 1999 2.5 diesel automatic. The OBD makes connection with other ECUs, like the engine, EAS, etc. It just doesn't connect with the WABCO or HEVAC. Actually the fuse for the OBD did blow a couple weeks ago, seemingly randomly. But we replaced it.

It happens when you brake at any speed. In fact we were driving just now and the ABS & traction failure came on again.

mystery · 2025-09-09T10:50:19+0100

may help

pwood999 · 2025-09-09T11:42:29+0100

Most OBD readers will only connect to the V8 engine. Very few if any will talk properly to the diseasel ECU. EAS, HEVAC, WABCO & SRS are generally not supported, except in Nanocom, Faultmate or Testbook.

==================================

In case anyone wants to know why, if you look at the OBD pin designations, it becomes clear. For example, P38 EAS uses pins 11+12 for data & pin-1 to triger the delay relay & start diagnostics.

The OBD specs have pins 1, 11 & 12 as "Manufacturer Discretionary", so most code readers do not even have these pins connected !!

Most of the other ECU are on the K-Line pins 7 & 15, but the LR ECU's are not standard protocols.

https://www.flexihub.com/oobd2-pinout/

feyniriel · 2025-09-09T12:50:12+0100

pwood999 said:
Most OBD readers will only connect to the V8 engine. Very few if any will talk properly to the diseasel ECU. EAS, HEVAC, WABCO & SRS are generally not supported, except in Nanocom, Faultmate or Testbook.

==================================

In case anyone wants to know why, if you look at the OBD pin designations, it becomes clear. For example, P38 EAS uses pins 11+12 for data & pin-1 to triger the delay relay & start diagnostics.

The OBD specs have pins 1, 11 & 12 as "Manufacturer Discretionary", so most code readers do not even have these pins connected !!

Most of the other ECU are on the K-Line pins 7 & 15, but the LR ECU's are not standard protocols.

https://www.flexihub.com/oobd2-pinout/

Yeah we have a Nanocom!

kermit_rr · 2025-09-09T13:25:25+0100

so it could be water ingress/corrosion issue. if the passenger well gets wet, it probably drips through/around the obd connector. check/clean it

Datatek · 2025-09-09T14:30:42+0100

WABCO is in your car and the ECU is a know failure item. Check the OBD socket front and rear for corrosion first.

kermit_rr · 2025-09-09T18:06:57+0100

Datatek said:
WABCO is in your car and the ECU is a know failure item. Check the OBD socket front and rear for corrosion first.

I think the D is more prone than the C model? Or both similar?

P38 traction/ABS problem

feyniriel

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