Ignition ecu help, maybe dead

[Andy_]

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70944

Hi guys, as some of you may know, ive been chasing a weak spark problem.
The positive side of the coil has all tested good, negative not so good.

As i understand it, the ignition ecu should ground the white / silver wire (negative side of coil) with the key at run.
Im getting 0.46v
I have unplugged the rpm relay, binnacle, idle relay (idle ecu). Still 0.46v on white / silver.
I have now cut the white/ silver as it comes out of the ignition ecu, the ecu is supplying 0.46v , not a ground. Green wire is 12v, resistance to distributor sensor 500 ohms.
Is there any wiring fault that would make the ecu put out half a volt on white/silver? The inside of the ecu looks good enough (by my untrained eyes), should i just get a new ecu (which seems to have jumped up in price recently). Ive read somewhere a Volvo 760 early 80?s one will work and is cheaper???
Heres some pics of the ecu in case it helps.
Any help appreciated!

//Edited to make it easier to read

[David T]

Before buying an ignition ECU I would replace the ignition coil and the coil in the distributor, they are cheaper and more prone to failure. Also check each wire into and out of the ignition ECU, a bad connection can also be the cause. There is a troubleshooting chart in the Technician training service manual to follow to test the ignition circuit.

[Bitsyncmaster]

I would think 0.46 volt is normal. The ECU uses a 400 volt or higher rated transistor to get the ground. With engine stopped it will be at the "ground" all the time on the stock ECU. You should read a little lower at the ECU pin referenced to the ECU ground. The wiring harness drops some voltage (it will read higher) if reading at the coil.