TRACS/ABS: Weird ABS problem:- HELP PLEASE

[mike19691969]

Hi,
Hoping someone can point me in right direction.
Car is a 99 registered MY2000 V70 T5 Auto. Symptoms started during recent exceptional hot spell if anyone thinks its relevant.

Starts fine and all lights are out, when trying to accelerate TRACS light flashes and car will not rev out. This can last for 2 - 10 minutes then ABS, TRACS and Brake failure light come on steady and car then pulls like a train and will not repeat until switched off and on again.

Read DTCs and had Left front and Right rear ABS sensor faulty signal along with ECM-6B00. I thought this could be logical enough as the ABS module thought 2 wheels were spinning/locked and therefore cut the power. However when I drive car with live data from abs sensors the Front 2 are reading fine but NOTHING from either rear. At the moment the TRACS starts flashing the reader, Launch, says "product not supported" on the data stream for all sensors.

I then suspected the ABS module solder problem and as it had never been opened I carried out the solder reflow but there was no change.

I then ordered a second hand ABS module, same part number, and fitted it. the same problem is there but now I don't have ANY Sensor DTCs at all, ECM one still there.

All Rings etc look ok, 2 front replaced in past 18 months, and ALL sensors are returning resistance from 630 - 840ohms, which I think I have read is OK. Car runs ok with ABS Module disconnected though I obviously can't tell if sensors are reading as the data comes through the module.

Broken wire?
Still a dodgy module?
Sensor/s?

Thoughts and pointers gratefully received.

TIA
Michael

[Shinsplintz 101]

Rear abs rings, worth a closer inspection if not replaced recently.

Also you can get a faulty connection from the rear sensors in where they join the loom in the boot.

https://www.pelicanparts.com/techart...placement.htm#

[mike19691969]

Thanks for the reply.
I have been digging a bit further and have now come up with the following.

1 Tested continuity from rear plug under seat to module plug. ALL GOOD

2 Having identified the pins in the plug for rear sensors I then checked resistance at the module plug and one side is now showing nothing but had been registering before. Other side is 743 ohms. Can’t tell left or right as both on same plug, but will have to be changed as a pair.

So rear sensors are now suspect and I think I’ll change them. Bottom end should be straight forward but has anyone any pointers for top end where they go round petrol tank? Is it enough to tape new plug to old wire and pull through?

PNever been done in my 8 years of ownership so god knows how old they are.

[Baffler]

Originally Posted by Shinsplintz 101

Also you can get a faulty connection from the rear sensors in where they join the loom in the boot

Agree with Shinsplintz here...assuming the reluctor rings are in good nick try cleaning the loom connections with contact cleaner before you replace any parts. Also, no harm disconnecting the battery whilst cleaning to reset the ECU values.