Yesterday I started trouble shooting using this link I found surfing the forum. http://ww2.justanswer.com/uploads/ba...ion_module.pdf

This a.m. truck started up quick. Idled briefly then stalled. Tried again, no start. Checked for spark, no spark. Checked everything out according to the TSB. I found the foil wrap in tact but worn out, just no foil left. Not much foil just dust. Drain wire appeared to be in good shape but appeared to have corrosion dust. It was solid. I decided to peel back as far as I could back to the harness junction just where the harness enters the fuse box. After that I walked away from the truck. Went back to it and hour later, turned the key, started up. Idling nice. Went back to the harness and slightly squeezed the bundle of wires just in front of that junction at the fuse box and the truck tried to stall. Let go, truck came back to a good idle. Squeezed harder at same spot, truck stalled. Thought hey, might have found the problem. Wrapped wires were located inside the bundle. Removed foil wrap and inspected wires. Wires appeared clean, no breaks, slices, etc. Same for drain wire. Foil was shot. So tomorrow I will go at it with a magnifying glass or my cheaters.

I am curious if anyone else has troubleshooted according to the TSB and what did you find as far as concerns during the inspection. I am seeing nothing at this time. That doesn't mean nothing is there. I will check again for continuity/resistance at the wires tomorrow. Thanks.

 

Still working on this no spark issue. Coming down to "I think" bad wire in harness or maybe issue with PCM. Pulled the PCM yesterday just to take a look for any obvious signs of concern. That baby was very clean, board looked brand new. No leaking caps, also. The only thing I did notice was a sticky brown like substance on the bottom of the box exterior where it sits on the bracket support. I only visually inspectd the front of the board so am not sure if anything on the back side of the board could have some problems. Anyway I have noticed there are a few places out there that will test a PCM. I might go this path for now just for peace of mind. If it tests good then I more than likely have harness problem. Special thanks to Subford as we communicated on several occasions. He provided me with a good information on the right direction to pursue this problem of no spark. Moving on.

 

If the PCM is disconnected (unplugged) and you have no spark then it is NOT the PCM Computer causing the no spark.
As it would be completely out of the ignition spark generating circuit (system).

 

Thanks Subford. I did have no spark with the PCM connected on many attempts at starting with no spark. It was my understanding that a faulty PCM can be a cause of a no spark condition also when it is connected?

 

subford was asking you if you checked for spark while the computer was unplugged?

If you have no spark with the computer unplugged from the main harness connector? then the computer is not the fault for its no spark condition.

If you have spark with it unplugged but loose spark when its reconnected? then the computer is causing problems that need to be addressed.

Test it both ways a few times though to be sure of any findings, eliminate unplugging it and having spark return as nothing more than happenstance.

If the computer is the sole problem spark will return consistently when the computer is unplugged, getting spark two out of three times when its unplugged is not conclusive.

 

Thanks danr1. Based on Subford and your input I can rule out the PCM as the problem. Spark does not return consistently when the computer is unplugged. Thanks for the input.

 

Can anyone provide me with a PCM pin out chart for my 96 F250 5.8L EEC-IV? Might the pin out for my vehicle be the same as earlier years even with different engine? Prefer a wire description also? Thanks.

 

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Thank you much Subford!

 

Subford, do you have a wire diagram of the engine side distributor connector identifying wire path and color? Thanks.

 

The below is the engine side.
C178M


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After pulling and looking at a distributor the above image would be the engine side of the plug.
And it would be C178M.

 

That is exactly what I am looking for. If I probe #8 at the distributor truck side connector and #6 PIP wire at ICM I should be able to get a conclusive resistance and or continuity reading, shouldn't I? Disconnected on both ends, also at computer? If I remember it branches towards the computer and to ICM?

Also, how can the shield ground (I am asumming it is the shield wire) be tested since it isn't connected at one end? Expose it towards the ICM and probe at both ends? Thanks.

 

Yes, it sholdd be near zero ohms.
Yes have all three points disconnected.
Yes it does.
That would work if you are on the foil at the ICM end.

 

Today I had a chance to check some things out. I probed PIP wire running betwee ICM connector and the junction box, next to fuse box on fender, (separated box) for ohms and had a reading of 4.5 m ohms and climbing slowly but steady. I am not sure if that is too much resistance? I then switched my meter over to continuity and had an open circuit reading on that same section. So maybe the resistance reading doesn't matter at this point. Checked, rechecked, checked again, pretty consistent. Also checked for resistance and continuity on that same wire from that junction box to engine side connector at distributor. No issues there. All my grounds are good using a test light. Soooooooo I am thinking I may be getting somewhere. Last time I had spark I showed between 4 and 5 volts at the ICM, but truck wouldn't start. Sounded like it might have fired briefly but then lost spark. Not able to put in the time I want to right now on this issue but will keep you posted on progress.