My 94 850 turbo is exactly back where it was when I bought it. No spark, per the ecu I believe. Power to the coil and other components that Ive tested. Certain channels on my diagnostic module arent responding, just a dim glow when I plug in the test lead. I'm so frustrated with this car, but I will get it figured out one way or the other . I would like some help populating a list of sensors/components that can cause a no spark from the ecu if their values/functioning are faulty. I'm new to Volvo and their systems, so any help with this list would be greatly appreciated. My strategy at this point is this: Ive rigged up a test harness at the ecu to substitute for a breakout box, using the ecu (the Bosch ecu is what concerns me) ground for the neg. and I'm going through the pinouts one by one and comparing the values to a diagnostic table of voltage values that I found online somewhere. By looking at the values as the ecu is receiving them, I hope to find a discrepency with the table and then try to isolate the problem. A list of no spark conditions would help me a lot in narrowing things down and eliminating possibilities. So far I have discrepancies for the acceleration sensor power supply, torque reduction signal from transmission control module and load signal to trans. control module. Some of the disagreements in voltage could be due to the lack of idle though. Sorry to keep beating on this boring topic but I need to figure it out. Thanks a lot.

 

I've highlighted almost everything connected to the spark lines. This is an overkill but hope would be of some use.


JPN

[IMG]local://upfiles/6892/87FCBA8C6EA549F1BEA72203432BB64D.jpg[/IMG]

 

Thanks for the help. I think I have that diagram somewhere, but u got me thinking in a new direction. I was focusing on the efi ecu as the lack of spark signal, but tracing the lines upstream from the coil (spark signal not power) isn't a bad idea. This thing is making me insane. I don't know if you remember me from about 6 months ago, but I had the same problem and removed most of the ignition etc. and replaced some related sensors. I cranked to check battery and it started right up and ran great for about a month. I went to fill it one day and it just died at a stop sign. Nothing since and same symptoms. I thought maybe water somewhere because it died on a steep incline after running great on level ground for a month. Probably not but just a thought. I'm going to check the continuity on the lines in the diagram, and post results. Thanks a lot.

 

No prob I hope the system comes back to life.


JPN