2004 V70 Rear brake light issue

[Mkengineering]

So after going through the whole car and checking every single fuse that could possibly be culprit I've come to the conclusion it's the brake pedal switch.

I haven't got thay relay which everyone has been mentioning.

Going too order a brake switch and wee if that cures the problem

[XC70Bob]

Originally Posted by Mkengineering

So I am bit confused.

I've gone into the passenger rear and taken apart the fixture to find this?

My one looks nothing like what you guys are showing me?

So that is the later REM , I suspect your car is a late 2004 register car which is actually a 2005 model ( my XC70 is exactly the same ), it does not have the external relays all relays / drivers are internal and not replaceable.

If your 3rd high level brake light is working correctly its unlikely to be the switch on the brake peddle that's at fault as it just sends a signal to the CEM which interns instructs the REM to turn on both the brake lights and the high level brake light.

[stuart bowes]

brake switch faulty would also stop cruise control working I believe (or make it refused to engage?) which might be another way to test?

unless it relies solely on the brake pressure sensor maybe, not 100% sure on that

anyway this sounds like it might be another job for https://volvodiagnostic.com/en/contact-us

[Mkengineering]

Originally Posted by XC70Bob

So that is the later REM , I suspect your car is a late 2004 register car which is actually a 2005 model ( my XC70 is exactly the same ), it does not have the external relays all relays / drivers are internal and not replaceable.

If your 3rd high level brake light is working correctly its unlikely to be the switch on the brake peddle that's at fault as it just sends a signal to the CEM which interns instructs the REM to turn on both the brake lights and the high level brake light.

Sorry for sounding stupid here but how do I fix then? I plugged the car up again using vida and it came up with CEM 8D02 faulty.

When doing a Google search it looks like unit under the steering wheel colum that I'll need top replace?

Just spent £70 on a new brake pedal switch from volvo which will be here tomorrow

[stuart bowes]

when he said not replaceable I think he just means you can't pull one out and push in a replacement

I'm fairly sure the unit will still be repairable

I would email the people in that link I posted above and describe your symptoms

If its the REM, at least you can be glad it's easier to remove and send somewhere than the CEM which is a total pig to take out

for you it's only an hour round the M25 anyway it might even be easier to take the unit (in another car ideally) wait for the repair. there's an ASDA and a Mcdonalds right nearby but not a lot else. don't forget to pay the DART charge

[Lancee]

Originally Posted by Lancee

I had similar years ago, I believe it was in the RM15 position. If I recall correctly my car had an original dual relay which handled both the upper and lower lights. I believe it was replaced by two updated single relays from my Volvo main dealer, one did the upper light and one the lower two lights. This is only some guidance on my part, my memory is not what it was so don't hold me to anything, including any illustrated part numbers !

https://www.volvoparts.tmsmotorgroup...42-12420-p.asp

Some apologies, the car which caused me the earlier issue is a MY02 car, I assumed (dangerously!) that your MY04 car would essentially be the same. I also have a MY06 car which having just physically looked at does (apparently as yours) have the later REM without the readily replaceable relay/s. In my defence I did say it was only guidance and not to hold me to anything !

[XC70Bob]

Yes I meant you can't just unplug a relay and replace it, they are all internal and soldered to the PCB, I would recommend Volvo diagnostic I have used them myself and found them very helpful.

I think they now do a full repair service just just need to get the car to them and they will test and remove any modules that need repair, do the repairs reinstall and hand you back a working car.

[Mkengineering]

Originally Posted by XC70Bob

Yes I meant you can't just unplug a relay and replace it, they are all internal and soldered to the PCB, I would recommend Volvo diagnostic I have used them myself and found them very helpful.

I think they now do a full repair service just just need to get the car to them and they will test and remove any modules that need repair, do the repairs reinstall and hand you back a working car.

Well I've removed the CEM and have booked it for repair with volvo diagnostic.

Hoping it resolve mu issue as I really don't want too scrap a good car.

Only recently got the timing belt and water pump and drive belts sorted.

I really can't be bothered tool deal with electronic faults.

[stuart bowes]

CEM? or REM?

[Mkengineering]

Originally Posted by stuart bowes

CEM? or REM?

Cem.

I give up, tried all morning too remove the cem. After removing various bolts and cutting my hands up squeezing into the footwell, its not worth the hassell

I've booked it for it too scrapped