ABS control unit repair

[greyv70]

First of all thanks to the many people that have contributed to this post. I would never have attempted such a repair without these detailed photos and descriptions.

On my car the engine ECU light and the tracs and ABS lights were the original lights to come on the dash.
I had the fault codes read by my local volvo dealership, the faults were ECM-510D vehicle speed signal, ABS-0010 and ABS-0011, left front signal missing and left front signal faulty. The dealership said straight away it was the ABS module.

So I found this thread and my first attempt at soldering resulted in the lights staying out for about 130 miles. At this point an extra light came on being the flashing orange arrow (faulty automatic transmission). I then followed oliverpervasive's advice regarding the electrical sockets which has resulted in only the ECU light staying on. I am anxiously awaiting the silicone to dry following my second attempt at soldering, but in case this doesn't work I might have to find another unit. My question is does a replacement ABS module need to be mapped to the ECU (by a volvo dealer) or is it just a case of finding the right one from a breaker's yard? The volvo dealership seemed to think it needs to be mapped.

In case anyone is interested how much this would cost from volvo, I was quoted £700 for a new unit, plus one hour's labour, plus vat coming to about £900.

[greyv70]

My ECU light is still on this morning unfortunately, which leads me to thinking that maybe the ABS module was only part of the problem. Presumably the "ECM-510D vehicle speed signal" is generated from all four ABS sensors?

Thanks in advance for any further help on this

[acshortt5]

Just done this last weekend.

You need to find an ecu with the matching part number.

To refit you simply undo the 4 screws holding the ECU in from underneath (E5 socket required, don't try using anything else or you will strip the screw heads) - access is tight and a bit fiddly but I had mine swapped over in 15-20 mins.

The ecu will drop down so keep hold of it when you take out the last screw.

They don't need mapping and are completly separate from the brake fluid so you don't need to worry about bleeding the brakes either.

Literally take the old one out, put the replacement in and away you go.

This is of course assuming you have a P1. I.e. a V70 up to 1999.

If you have a later one which runs the canbus management system then I believe they may require a software download as the abs links in with various other ecu's.

It would help if you could confirm what car + model year you have.

[greyv70]

My car is a 1998 2.5 20v auto (non-turbo).
Its good to know that it doesn't need mapping to the main ECU (contrary to what the main dealer told me) I think I'd better find myself another control unit. Out of interest what is a reasonable price for a second hand module? £40?

[acshortt5]

Originally Posted by greyv70

My car is a 1998 2.5 20v auto (non-turbo).
Its good to know that it doesn't need mapping to the main ECU (contrary to what the main dealer told me) I think I'd better find myself another control unit. Out of interest what is a reasonable price for a second hand module? £40?

I got mine, which came with the pump as well, for £70 + p&p.

They are quite hard to find 2nd hand actually. As mentioned previously you need to find the correct one (look for the part number on the underside of the ecu using a mirror or camera) - there are quite a few different ones.

There are quite a few places that will repair them or you could have a go yourself.

You can take off the ecu and the brakes will still function normally but you will be without abs (and tracs if fitted). So if you lock the brakes you will need to do cadence braking to avoid skidding.

[Chris_Rogers]

The brakes won't function normally without the ECU as the electronic brake force distrubutuin won't work. It could be said if the ECU is playing up then it probably wasn't anyway.
The risk is the rear wheels can lock and cause a spin.

[Yosser]

Originally Posted by Chris_Rogers

The brakes won't function normally without the ECU as the electronic brake force distrubutuin won't work.

Not true for P1 cars (they don't have EBD).

[^^ I'm not right about this. oops ]

[Chris_Rogers]

Yes the do!

[Yosser]

Originally Posted by Chris_Rogers

Yes the do!

I stand corrected, I shall return under the rock from whence I came....

[acshortt5]

Originally Posted by Chris_Rogers

Yes the do!

Er, no they don't. Certainly not to the extent where the brakes won't function at all.

The Me7 ones have a stability control system(STS) but the earlier cars have a more basic system with valve splitters.

When the abs ecu is taken out/not functioning the brakes will continue to work on the pre me7 cars and, I believe on the me7 cars as well.

Not that I'm advising anyone to drive with the abs disabled for a continuous period - which afterall would be an mot failure. But for a short period while an ecu unit is being fixed the car will still be able to be driven - I would personally take more care and avoid fast driving etc though.