For the last three years my V70 AWD has intermittently had the ABS/Trac warning indicator lighting up. Recently it is on most - but not all - of the time.

A volvo dealer says there is a 'permanent' error code on the O/S rear wheel rotation sensor (although the problem is only intermittent). They suggest fitting new rotation sensors (about £250) and if this doesn't work I may need a new ECU (£400+).

This seems a bit heavy duty. Is there anyone out there who knows:-

a) is this a common fault?

b) is there a cheaper way of trying to solve it?

Incidentally I have already dismantled and had a look at the sensor. It was very dirty but after cleaning the warning lights were still on.

Any advice much appreciated.

Martin (fuseman)

As I understand it, you will often get failure codes for the wheel sensors, but the actual culprit is the ABS control module. Replace that, and the sensors may behave again.

Gerald C

The circuit board cracks, typically breaking the connection to the RR wheel (hence the OBD scan code for a rear wheel sensor). The ABS module is under the pump block. The part sells in the US for $416 at the dealer, $358 online. The replacement module is of better quality and construction, and repeat failures are very rare.
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David
98 S70 T5SE // Black, misc mods (mostly lighting), red calipers
92 940GLE // Hella Micro DE foglights

Thanks David - this is what everyone is saying. I've located the controller and also an online supplier (similar price in UK to US). Looking at the unit it appears to be fixed on with 4 or 5 small star-shaped bolts under the ABS unit. Do you know by any chance if it is just a matter of undoing these to replace the controller?

Martin (fuseman)

Exactly.
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David
98 S70 T5SE // Black, misc mods (mostly lighting), red calipers
92 940GLE // Hella Micro DE foglights

FUSEMAN,SOUNDS LIKE YOU ARE GOING TO NEED A NEW ABS MODULE,IT SEEMS TO BE A COMMON FAILURE.MY 98 AWD R DID THE SAME THING.GOOD LUCK.

the abs tracs control module is not a servicable part, which means you shouldn't take it about and try and clean it. Since your car is tracs car, the part number (usa) is 8602266, unless your car is an AWD or Cross Country which I think has a different p/n.

the abs tracs control module is not a servicable part, which means you shouldn't take it about and try and clean it. Since your car is tracs car, the part number (usa) is 8602266, unless your car is an AWD or Cross Country which I think has a different p/n.


ACTUALLY, it is sealed, but servicable. I stated in a previous message that I had mine repaired and added an extra heat sink to help eliminate the cracking to the board again. Mine cost <$150.00 to have repaired.

Mike

Just bought a used 98 V70 AWD. Following this thread on athe ABS / Tracs light because mine does the same thing. Is this part easy to replace for someone who is reasonably handy under the hood? Where exactly is the module located ?

Under the ABS pump block. There's another thread here from people who've done this - not a bad job but working space is a little cramped. You'll need torx bits...and swing the fusebox out of the way.
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David
98 S70 T5SE // Black, misc mods (mostly lighting), red calipers
92 940GLE // Hella Micro DE foglights