Is my pcm fried? - Ford Powerstroke Diesel Forum
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post #1 of 7 Old 01-29-2008, 11:26 AM Thread Starter
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Is my pcm fried?

My 97 f250 7.3 died on me suddenly. Got it towed back to the house and put a scan tool on it. Unable to communicate. Tried another scan tool, also unable to communicate. No wait to start light when i turn the key to on. Tach does not move when the engine cranks.
All of my fuses located below and left of my steering wheel are good.
Are there any other fuses or fusible links along the power route to the pcm?
Any help is greatly appreciated.
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post #2 of 7 Old 01-29-2008, 01:24 PM
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I don't do pre99 well but I hear it is fuse 22 under the hood for the fuel bowl heater and you just unplug the heater and change the fuse and forget it.

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post #3 of 7 Old 01-29-2008, 01:30 PM
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check the relays.....the easiest way to just do a simple check is just to swap them around...

Unplug the fuel heater to be safe as was said above....

try disconnecting the electrical connector on the tranny and see what happens. Ive seen shorted out solenoids in the tranny cause this same concern....

Generally though....when the wait to start light doesnt work...its a PCM problem......but its not as cut and dry with the OBS trucks as it is with the superduties...with a superduty its about 95% of the time....with an OBS its about 75% of the time....
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post #4 of 7 Old 01-29-2008, 01:49 PM
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I have a 99.5 and it done the same thing unable to communicate, and no wait to start light, and yes mine was fried. but yours may not be good luck

1999.5 6 Speed
Tony Wildman 6 Pos Chip
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post #5 of 7 Old 01-29-2008, 01:50 PM
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Fried my chip to thats why im back to stock

1999.5 6 Speed
Tony Wildman 6 Pos Chip
AEM Intake
4'' Exhaust
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post #6 of 7 Old 01-29-2008, 01:59 PM
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I dont know about the 7.3 but with my 6.0 when I fried my pcm I couldnt even get the truck to crank at all. I had nothing just turn key. worst thing ever

-Evan

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Yeah, but your trucks a freak of nature...
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post #7 of 7 Old 01-30-2008, 06:08 AM
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I have fried my computer before and it will crank just not run and no wait to start light. The exact same symptoms will be there if the computer looses power and usually when it looses power it is the fuel bowl heater has blown one of the big maxi fuses. I thin it is fuse 22 on the old trucks and 30 on the newer ones but I'm not sure, hasn’t happened to me yet. Probably cause I don't have a filter heater anymore.

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