bad pcm??? help
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Joined: Jul 2011
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bad pcm??? help
hi guys. have a 2005 f250 5.4 auto trans and the past few days the truck has been stalling randomly while driving and some times not restarting right away. now today it stalled a few times. once while driving, once when i sitting in it trying to load up obd2 scanner.i got it home and it started running rough for 2 mins then it would stall out. it did that 3 or 4 times and now it stalled while sitting in drive way and wont start at all. it wont crank. no fuel pump noise any more. the odometer goes out and just has a bunch of flat lines. i can not get scanner to connect anymore. it never had any codes before when it was stalling. when i could get scanner to work it had 42psi of fuel pressure. battery and starter are good. all the fuses are good and i can hear the pcm relay clicking when i turn the key and swapping relays does nothing. i can hear a very rapid clicking noise from the throttle body area. any clue what that could be? is the pcm fried? what would cause it to fry? how can i test pcm? if get used pcm does dealer have to program it? thanks lee
Postmaster
Joined: Jul 2015
Posts: 4,392
Likes: 22
From: very South Texas
How do you Know the battery is Good?... what tests.. type of tests..???
next is the connections from battery to starter AND battery to Grounds..
always start at the beginning.. and work from there.
and a few carriage returns would help in reading your message.
next is the connections from battery to starter AND battery to Grounds..
always start at the beginning.. and work from there.
and a few carriage returns would help in reading your message.
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
You have a vehicle power problem, most likely (specifically) one that's preventing the PCM from getting reliable, stable power or ground for its operation
You need to fix that before looking at anything else. Simply swapping stuff around isn't likely to cut it, you'll need real tools and tests.
You need to fix that before looking at anything else. Simply swapping stuff around isn't likely to cut it, you'll need real tools and tests.
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
Guess again. This is a half-ton... Go do your homework.
Cargo Master
Joined: Mar 2006
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From: Bend Oregon
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Lead Driver
Joined: May 2003
Posts: 9,303
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From: Lyndonville, Vermont
Well in 2005 I guess the start signal does come from the pcm...That being said sounds like he has a connection issue or alternator issue with what we got from him so far. I don't know what he has to do to get it started...ultimately.
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Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
Doh! In any event, the PCM controls the starter.
This is the key piece of evidence presented:
That is how the cluster is programmed to operate when it cannot establish communications with the PCM. That symptom, combined with the report of the scanner failing to connect, no starter and no fuel pump priming, all indicates that the PCM is not operating. That's usually caused by a loss of operating power or ground to the PCM. A slight chance the PCM has died, but operating power must first be checked to avoid unnecessary replacement.
This is the key piece of evidence presented:
the odometer goes out and just has a bunch of flat lines.
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