96 7.3 with no wait to start lamp/no communication

FordFanaticTony · July 28, 2011

Hey fellas. I am working on a 1996 F-250 with a 7.3. It came in with a no start. I took the IDS over and found no communication and the wait to start lamp will not come on. I tried to force the calibration and it took it for some reason. I found three transmission codes at KOEO P0741, P0755, and P1754. Drove the vehicle and it stalled on me after about a mile. I restarted it and limped it back to the shop. It dies the minute i let it idle. Got back and scanned it and found codes P0472 and P0344 in memory. Replaced EBP sensor since I have seen them cause a short to vref on the PCM causing no communication and also the cam sensor. Vehicle started. Next day, again no start no communication and no wait to start lamp. Anyone seen this one before?

Mbl35 · July 28, 2011

No, but i got a customer with a 99 f350 7.3 4x2 with no start & no communication and no check engine lt. when you turn the key on, i think the pcm.

Bruce Amacker · July 28, 2011

I'd be putting a breakout box on both of these and check basic power and ground voltage levels for a start. IIRC, some/all 7.3s CEL go on and off at a normal key cycle. PCMs are a low failure rate on these.

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Mbl35 · July 29, 2011

Right, thats what i told the customer. I did not physically check it but he insists over the phone he needs a processor and he wants me to get one for him.

Brad Clayton · July 29, 2011

Quote:

PCMs are a low failure rate on these

But if someone piggy backed a chip on it.......

FordFanaticTony · July 29, 2011

mBL 35 disconnect the ebp sensor at the front cover and see if you have communication after that. I had one shorting out the 5vref to the pcm. I removed the pcm from the 96 and see that the rear cover on the pcm is missing. this one clearly use to have a chip piggy backed on it. Would that cause a problem to the pcm or would the pcm being exposed without a cover possibly get damage due to moisture getting inside?