ABS TRACS lights coming on intermittently

[El Padrino]

The dreaded ABS TRACS lights have been coming on intermittently. The brake pedal can sometimes buzz before they come on. If I'm using the car the next day, the lights will be on upon starting, then go off after a few seconds and stay off for a few days, until the cycle repeats.

My ABS module was rebuilt in Jan 2023, along with the o/s/f ABS sensor replaced with a new one. In July 2023, I had the n/s/f ABS sensor also replaced with a new one. I took the car back to the indy I've been using for the past couple of years who carried out the work. They have checked the reluctors, speed sensors etc and both the wheel bearings are new, but can't find a fault via a scan. They said the lights need to stay on permanently for the scanner to pick up any errors. *** I had the wheel bearings done at a different place who noticed the ABS TRACS lights came on, so they did a scan and they said it pointed to an issue with the ABS module ***. If it was the module, then surely my usual indy's scanner would have picked it up. I feel a bit fobbed off by them (I'm sure that's not the case), but if they can't find a fault, then I guess they are stuck too.

I'm bit concerned that MOT time will be coming up in a few months. I really don't want to scrap the car. Not due to the fact I've spent quite a bit of money so far putting things right when needed, but it's my first Volvo (V70R) and I really like the car.

So, I'm in a dilemma. I was thinking of buying another working ABS module, get it fitted and see if that solves the issue or bank on the lights not coming on at MOT time. Very unlikey the latter will happen due to sod's law.

Your helpful thoughts as always please.

[SteveSarre]

Hi

Depending on year of the car, you could buy a cheap OBD bluetooth dongle for about £8 and a mobile phone running the free Torque app or the 850 OBD-II app (for early models)), and catch the code when the light next comes on?


Steve

[SteveSarre]

Hi

And I believe you will have rear wheel speed sensors as well as front.

https://www.pelicanparts.com/techart...eplacement.htm

Steve

[El Padrino]

Hi SteveSarre,

Thanks for your replies. The indy has checked all the speed sensors, reluctor rings, ABS sensors, everything. I do have a OBDII reader with the Torque app and there was no code captured even when the ABS TRACS lights are on. Driving her yesterday, I noticed I lost the speedo (rev counter was still working). The speedo came back after switching off and on the engine and the ABS TARCS lights went out.

I found the following thread - https://www.volvoforums.org.uk/showthread.php?t=191451 and going to try the plastic/cardboard wedged in between the ABS pump and module fix via this link - http://www.carinstructions.com/volvo...70-abs-module/

Upon looking at my ABS pump and module, the wire block connecting into the pump is exposed. Looks like the cover is missing (circled in the photo) and secured with a grey zip tie. I wonder if dirt has entered the wire block connector and causing the intermittent issue. Should I use switch cleaner to clean it out? How should I approach it? Can I still wedge a plastic credit card in between as per the http://www.carinstructions.com/volvo...70-abs-module/ link? Looking at the fix in the photo, the piece of black plastic is wedged between the ABS pump and the black cover for the wire block connector. What would the plastic credit be wedging between if my cover is missing?

[Luxobarge]

Originally Posted by El Padrino

I do have a OBDII reader with the Torque app and there was no code captured even when the ABS TRACS lights are on.

That means that your scanner isn't picking up the codes, if the light is on there WILL be a code, maybe you need a different method of reading the ABS codes?

Losing the speedo is actually a good clue, as it's driven by the front left ABS sensor. Of course the fault could be in the wiring or the module, but at least you know that there may be a fault in that area.

Don't worry too much about the plug cover, they're fairly fragile and break, mine did and I also just have it tied on over the plug to prevent splashes getting into the connections.

Yes, I should think you can still try the wedging technique without the plug cover, IIRC on mine there's still something to wedge against.

HTH

[El Padrino]

Originally Posted by Luxobarge

That means that your scanner isn't picking up the codes, if the light is on there WILL be a code, maybe you need a different method of reading the ABS codes?

Losing the speedo is actually a good clue, as it's driven by the front left ABS sensor. Of course the fault could be in the wiring or the module, but at least you know that there may be a fault in that area.

Don't worry too much about the plug cover, they're fairly fragile and break, mine did and I also just have it tied on over the plug to prevent splashes getting into the connections.

Yes, I should think you can still try the wedging technique without the plug cover, IIRC on mine there's still something to wedge against.

HTH

Thanks Luxobarge, should I still clean that block connector? Shall I wedge say two credit cards into this space (arrowed)?

[Luxobarge]

Originally Posted by El Padrino

Thanks Luxobarge, should I still clean that block connector? Shall I wedge say two credit cards into this space (arrowed)?

Yeah, cleaning it can't do any harm, and it'll more than likely help. While you've got the big plug off, there's a little (I think white) 2-pin connector that provides the main power to the ABS, that sits next to it. Give this the most attention, I've had a lot of problems on mine with it not giving a decent connection, and therefore supplying dodgy voltages to the ABS module, Clean it thoroughly, perhaps tighten up the connectors if possible, and re-seat it multiple times (ideally soaked in contact cleaner). Don't use WD40, it'll likely make the contacts worse.

Yeah, I reckon put in as many wedges as you like, until it feels firmly wedged!

[El Padrino]

Originally Posted by Luxobarge

Yeah, cleaning it can't do any harm, and it'll more than likely help. While you've got the big plug off, there's a little (I think white) 2-pin connector that provides the main power to the ABS, that sits next to it. Give this the most attention, I've had a lot of problems on mine with it not giving a decent connection, and therefore supplying dodgy voltages to the ABS module, Clean it thoroughly, perhaps tighten up the connectors if possible, and re-seat it multiple times (ideally soaked in contact cleaner). Don't use WD40, it'll likely make the contacts worse.

Yeah, I reckon put in as many wedges as you like, until it feels firmly wedged!

Thanks. So, I need to unclip both the wire block connectors arrowed 1 and 2 and clean with contact cleaner. Is the 2-pin connector providing the power arrowed number 2? That's the only one I can see.

What is actually being wedged? If that multi-coloured wire block connector is being wedged away from the silver/grey metal pump, is that making sure the wire block connector is seated into the slot of the ABS module so it doesn't move?

[El Padrino]

ABS module now wedged. Will see how the ABS TRACS lights behave until I get some contact cleaner to clean the connectors.

[Luxobarge]

Originally Posted by El Padrino

Is the 2-pin connector providing the power arrowed number 2? That's the only one I can see.

Yes, that's the dodger I was talking about.

Originally Posted by El Padrino

What is actually being wedged? If that multi-coloured wire block connector is being wedged away from the silver/grey metal pump, is that making sure the wire block connector is seated into the slot of the ABS module so it doesn't move?

Yes, you've got it. I think the idea is that if there's a bad connection or bad solder joint it pushes them together more firmly by sideways pressure. Personally I'm not totally convinced about this "fix" but probably doesn't do any harm, and there seems to be plenty of experience on here that says it can work.