Help with ECM 1998 V70 manual wagon

gregoryahunter1 · Post by **gregoryahunter1** » 01 Jul 2025, 13:10

I would appreciate any help. I have a project 1998 V70 wagon with a manual transmission. Was running when I took it to a mechanic to get the clutch replaced. After clutch replaced , the mechanic couldn't get it to start and eventually gave up and I took it to another mechanic who has determined that the ECM is bad. Part number is P09155761. I have checked online and called a bunch of places and cant find this exact part. Is there any way to know what other part number of the ECM will work in my car? If not - is there some way to "flash" a different ECM to work with this car. Im hoping that this car is not bricked. Any other options or advice would be greatly appreciated! Picture of the ECM is attached

xanthefin · Post by **xanthefin** » 01 Jul 2025, 13:28

-This is murmuring-
Is this car required pressing clutch previously to start?

VGLA has feature to prevent start if it doesnt detect clutch being pressed while starting *if* this feature is programmed ON. It can be programmed OFF via App if this is being problem suddenly.

Post by **misha** » 01 Jul 2025, 17:32

And you need a Bosch part # from upper left angle.

Ecu can't go bad from a clutch replacement if it ran before that.
Don't bother with ecu replacement.

Post by **volvolugnut** » 01 Jul 2025, 18:27

Go back to the basics.
Does it have compression? Fuel to the injectors? Proper timing of valves? Ignition timing and spark?
This no start condition after major shop work sounds more like a wiring problem. Like a wire connection or sensor is not ready.
volvolugnut

Post by **abscate** » 01 Jul 2025, 22:34

Is it cranking, not firing?

Doubtful it is the ECM. If the reader is talking to it via OBD, it’s something else

gregoryahunter1 · Post by **gregoryahunter1** » 02 Jul 2025, 10:50

Thanks for suggestions so far - I will follow up on those

Here is the details from the mechanic:

" found several things unplugged including the ignition coil discharge module and camshaft position sensor, plugged those things in and checked for spark, found no spark, power and ground present at coil discharge module but no pulse from PCM, found 1.2v on PCM pulse wire, checked injector pulse and found no pulse, found system voltage on the power side of the connector and 6.5v on the wire that should be grounded by the PCM, this indicates a short or a failed PCM, need more time for diagnosis

Found wires smashed between clutch line bracket and transmission but no damage to wires, load tested the ground circuit to the PCM and found no faults, checked all power wires are getting proper power to the PCM, with the PCM connected there is 6.5v on the injector control wire, added jumper cables to engine and chassis ground and the condition did not change indicating it has all the grounds to the engine and chassis for PCM function, with the PCM disconnect there is no voltage on these wires and they are not shorted together, recommend replacing engine control module, can't find information on reprogramming a used ecm, confirm with programming service"

If this does NOT indicate a bad ECM - I would love to hear further suggestions.

Thanks again

Post by **abscate** » 02 Jul 2025, 23:48

You need to find someone who knows p80 Volvos to fix all the disconnected stuff and put it right.

I don’t know what a PCM is but it isn’t a Volvo thing, unless it’s the coil firing module?

I’m guessing it cranks but does not fire. You need to isolate if it spark or fuel missing.

Is Robert Spinner nearby? Anyone know his schedule ? If you are on a tight budget he can help

xanthefin · Post by **xanthefin** » 03 Jul 2025, 05:10

PCM is one of many synonyms to ECUs. I have heard it more with Ford guys.

Post by **volvolugnut** » 03 Jul 2025, 07:45

For a couple hundred bucks (maybe) you could send your ECM to XeModex to have tested. This may be wasted monry if they say it is ok.
You may have more damaged/pinched wires somewhere. You could remove all the wire loom and wire tie downs and inspect all the wiring under the hood. This is a big job, but possible.
Also inspect the pin connections at the ECM and connector harness. Pins may be damaged.
volvolugnut

V50M66 · Post by **V50M66** » 03 Jul 2025, 18:18

Oh geez. It’s a ‘98, it’s rather simple.

First off, PCM isn’t terminology used by Volvo or people that work on them, so that tells me his experience level with these things. Second, if the guy is probing stuff for power before doing simple checks, that confirms to me that he has absolutely no idea how to properly diagnose a -98 Volvo. They are very simple and easy to fix if you know what you’re doing.

I’ve never even heard of a case of a dead computer on one of these. It’s insanely unlikely that happened, especially while doing something unrelated like a clutch.

I can almost guarantee that a ground strap was not re-connected, the cam or crank sensor not plugged in, or the spade connector for the starter signal was not reconnected. Start there. It’s almost guaranteed to be something simple like that.

‘98 also doesn’t have vin-locked ECUs, so idk why this guy is confused about (unnecessary) programming - ya drop a new (used) one in and go. If you do want to try replacing it, you just need to get one from a ‘98 with the same engine and a manual, disconnect the battery, drop it in, and you’re good to go.

If it does actually need an ECU for some reason and this is a turbo car, get VAST Tuning’s Euro R ECU. It’s like $300, and you’ll get a significant power bump along with a new computer. You just have to match the injectors so it runs right (install blue/white injectors if not already equipped).

tl;dr
The tech who’s working on this thing is an idiot. Check all connections and grounds - it’s almost guaranteed to be something simple