S60 Electrics: ECU Swap

[Lugy]

Evening folks, quick one I hope, I've been offered an S60 2.0T Auto (2002) which has an ECU fault. I've been told that I can swap in a matched ECU, key and ignition switch from a working car but the information was a bit vague. Can anyone confirm if this is correct?

Cheers

Lugy

[reggit]

More or less certain this can't be done, but I could be wrong. If it has a faulty ECU, you're far better getting it repaired.
What's wrong with the car?

[Lugy]

Ah, boo! The car will only run on 4 cylinders, the car had a lot of time spent trying to diagnose the fault and I'm told the ECU was sent off for repairing but it turned out it couldn't be fixed.

[Bernard333]

I have been advised this can be done by swopping a matching set of ECM /steering column/key / fuse box / key transponder but I am not 100% certain it will work as may not communicate with existing modules such as CEM etc, a used set costs about £150 . Getting the ECM repaired seems most certain route or if not repairable it is possible to clone a working ECM with data from the faulty unit. I have a non starting V70 which I think has a faulty ECM but even with the aid of VCT2000/Vida cannot be certain its faulty, I do not want to go down the ECM repair route yet as I have not completely ruled out a wiring harness fault. Why does the seller think its a faulty ECM ? I have had a look inside D5 and T5 ECMs and looks to me with the right kit repairing the injector firing circuits may be possible and its probably these sections most likely to fail but searching the internet there is very little information on Bosch ECMs, lots of generalised stuff but very little specific info like a circuit diagram of the pcb, anyone got any links ?

[Lugy]

Hmmm, an ECU swap doesn't sound appealing if things won't work afterwards!

The mechanic that's been dealing with it tells me that he was told by the repairer that there's 3 wires that control the injectors, 2 wires that control two cylinders and 1 wire that controls the last cylinder, and that this last "wire" is the one that's faulty. I'd assumed that by wires it meant some overly complicated silicon witchcraft and that's what ruled out a repair! This information is now 3rd hand though so some may have gone AWOL.

It's a bit of a shame as it's actually quite a nice car and seems very clean!

[Bernard333]

I am not sure about the 3 2 1 wire configuration , if you take a look at the wiring diagram ECM to injectors and ECM to coil packs it shows 1 wire to each injector/coil pack and for the coil packs 3 earthed at a common point and 2 at another. Inside the ECM there are two power semiconductors, a type of MOSFET known as a TOPFET these two components are the only ones on the pcb which are capable of high current switching so its probable one controls the injectors and the other the coil packs but I have no idea how one device could control 5 injectors or another 5 coil packs without seeing the pcb circuit diagram , how they switch between 1 to 5 I have no idea and there are no clues on the pcb so I could be wrong. The D5 ECM is more obvious as there is one MOSFET per injector. If one device is controlling 5 injectors the problem may be nothing to do with the power section of the pcb, it maybe a software issue or perhaps not even a problem with the ECM , have the coil packs and injectors been tested and a compression test done on each cylinder ?

[Lugy]

This all sounds very complicated, electronics are up there with witchcraft and quantum physics to me! The car had a lot of time spent trying to diagnose the problem so I'd assume (you know what they say about assuming!) the basics were carried out!
The car is currently up for scrap value so might be worth a shot, even it it ends up being broken for spares!

Cheers,

Lugy

[reggit]

Go look at it and take a can of 'easystart' with you. With the engine running, give it a blast up the air intake, preferably after the MAF sensor - if the 5th cylinder picks up, you are looking at an injector fault (as this puts the fuel in the air stream). If it doesn't fire, I'd guess it's lost compression on that cylinder.

[Bernard333]

The Volvo/Bosch petrol ECM is witchcraft to me too at the moment Lugy , I have worked with power electronics for over 40 years and cannot figure this lot out , the diesel ECM by comparison is relatively easy to see whats happening . I am hoping someone on the forum who works with ECMs can explain how one power semiconductor can switch the supply to five coil packs and the second one control five injectors, there is no obvious way its done or have I got it completely wrong ?

[Chris_Rogers]

Don't think you can swap ECU's but you maybe able to clone your existing one into a secondhand one.

This trader may be able to help

http://www.volvoforums.org.uk/showth...light=throttle