1998 V70 Identity of ECU component

kjhiggins · Post by **kjhiggins** » 10 Jul 2014, 23:17

Does anyone know what the thing circled in yellow is, and should there be continuity across it?

: V70-1998-ECM.jpg (327.21 KiB) Viewed 1381 times

My '98 V70 has fried three ECU's in the last two weeks and I'm looking for indications inside the ECU's of what is getting fried. This looks like some sort of fuse and there is no continuity from side to side so I'm wondering if it is the component burning out each time.

Post by **abscate** » 11 Jul 2014, 03:49

Can you get a clearer picture of that component? I can't recognise it.

Board level testing of an ECU is high level repair..you should have that ECU case grounded and a twist strap on too, to prevent Damage. Testing continuity involves injecting current into components which can take them out.

kjhiggins · Post by **kjhiggins** » 11 Jul 2014, 08:34

Thank you for your suggestion. Using a camera I was able to get a much better view of the component, and it appears to be a 20K ohm resistor as measured with a DVM (I was using the continuity testing initially, and not looking at the resistance - that's why I thought there was no continuity.) The soldering job looks bad and the black around it made it look like perhaps it had overheated. Looks like I will have to continue my search for the bad component - and yes, I will ground the case and wear a wrist strap. (The original picture I used was from the web, and not my actual ECU.

Post by **abscate** » 11 Jul 2014, 09:22

I don't remember my resistor color codes but does that match a 20kOhm resistor as measured?

Ive never dived into an ECU so I can't help too much on this one. From the other thread, I think you have other problems with this car.

OldSkoolMadSkilz · Post by **OldSkoolMadSkilz** » 11 Jul 2014, 21:32

If your car has fried 3 ECUs, the issue isn't the ECU. If you can trace whatever failed back to a connector pin, you may be able to figure out which system is sending the over voltage.

kjhiggins · Post by **kjhiggins** » 12 Jul 2014, 23:54

Thanks for all your input. I'm trying to take a two-pronged approach by simultaneously looking for shorts in the car while trying to figure out what circuit is blown in the ECU. If I can determine the ECU circuit I can narrow down the scope of my search in the car, and if I find the problem in the car I can figure out which circuit in the ECU is bad and possibly repair it.

I'm going to do more research but I think the color codes are consistent with about a 25k ohm resistor.

Post by **abscate** » 13 Jul 2014, 03:28

The black looks more like its part of that mount than damage or failure but my experience inside an ECU is limited to this thread!

Do you know why your engine isn't firing? Compression, ignition , fuel, or timing?

kjhiggins · Post by **kjhiggins** » 13 Jul 2014, 21:16

Yes, I think the black is part of the mount. I was hoping to see something obvious when I opened the ECU but no luck.

The engine isn't firing because of the ignition system - there's no spark from the coil. The usual causes (cam sensor, crank sensor, coil) have all been ruled out by my tests and the shop's tests. I don't think the ECU is completely dead because I can still connect my OBD-II reader and I don't get any indication there is a problem - I would think if the ECU was completely dead the reader would give some error about not being able to connect. My current thinking is directed at the sensors that share A18 since one is the cam sensor and one is the engine coolant sensor - a bad cam sensor signal (not because of a bad cam sensor, but a problem with the circuit) would cause a no spark condition, and I did have a previous code about a bad coolant sensor but I didn't change it and the error code went away on its own.