OBDII not communicating with PCM
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Freshman User
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OBDII not communicating with PCM
have a '97 f250 7.3 diesel - have an edge evolution programmer that has been used for 3 + years now plus other mods made to intake/exhaust with no issues
recently, my programmer would not power up anymore when connected to the obdii port but that was an issue with the electrical connection to the cigarette lighter and now i have power
but all i get is "communication" error if i try to pull trouble codes now or try to power program it - went by autozone and theirs did the same thing and won't pull codes but will power up
HELP! do i have a wiring issue somewhere? seems i have plenty of voltage
other weird things happening - sometimes the ignition does 0 when i turn the key - change the key position so i can shift the automatic into neutral and back into park and then the ignition fires back up when i turn the key??
makes me wonder if my pcm/obdii communication issue is related to my ignition issue and is just electrical?
thanks in advance for any help - i'm stumped
recently, my programmer would not power up anymore when connected to the obdii port but that was an issue with the electrical connection to the cigarette lighter and now i have power
but all i get is "communication" error if i try to pull trouble codes now or try to power program it - went by autozone and theirs did the same thing and won't pull codes but will power up
HELP! do i have a wiring issue somewhere? seems i have plenty of voltage
other weird things happening - sometimes the ignition does 0 when i turn the key - change the key position so i can shift the automatic into neutral and back into park and then the ignition fires back up when i turn the key??
makes me wonder if my pcm/obdii communication issue is related to my ignition issue and is just electrical?
thanks in advance for any help - i'm stumped
VT Chapter Ldr
Joined: Apr 2004
Posts: 96,127
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From: Orange, Vermont
I'm not sure but is there a fuse in the system somewhere? On our 01 7.3 excursion there is a 20 amp fuse that is on the cigarette lighter circut. there is a short in the lighter so it poped the fuse and wouldn't communicate through the port until the fuse was replaced. I'm not saying the is fuse is wired with the cigarette lighter, but just a suggestion to check for.
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I thought it was a fuse issue at first when i had no power to the obdii but the fuse was fine and it was the electrical connector on the back of the cigarette lighter had come unclasped and i fixed it back and had power -- but now i get communicaton error with the pcm - have power and the fuse is fine
do u think i should look ignition first if it isn't firing correctly when i turn the key to turn the pcm on appropriately?
OR do you think i may have an electrical issue somewhere between the obdii and the pcm?
thanks!
do u think i should look ignition first if it isn't firing correctly when i turn the key to turn the pcm on appropriately?
OR do you think i may have an electrical issue somewhere between the obdii and the pcm?
thanks!
Postmaster
Joined: Sep 2007
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From: Medford Oregon
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Post Fiend
Joined: Dec 2010
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From: Orrville, Ohio
2x. This was my thought too I just didn't want to be the first to say it as I already have a reputation for being an Edge hater.
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FOREIGN GURU
Joined: Jul 2006
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From: Celaya, Gto. MX
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Freshman User
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Thanks guys for the advice. Would there be any store like autozone/advanced auto/etc that may have a scanner that will read a stroke without me having to purchase one?
i'm still not convinced the pcm is trashed -- i still think i may have some sort of ignition issue somewhere - just not sure where to start troubleshooting it
will the truck even start if the pcm is trashed? should i unplug it and try? don't want to ruin anything internal by doing this
if i have a faulty ignition somewhere (switch, etc), could that still start the motor without properly turning on the pcm?
need help and a starting point besides just tearing it all down and replacing things
anyway to test the pcm by itself?
thanks for any advise u can give!
i'm still not convinced the pcm is trashed -- i still think i may have some sort of ignition issue somewhere - just not sure where to start troubleshooting it
will the truck even start if the pcm is trashed? should i unplug it and try? don't want to ruin anything internal by doing this
if i have a faulty ignition somewhere (switch, etc), could that still start the motor without properly turning on the pcm?
need help and a starting point besides just tearing it all down and replacing things
anyway to test the pcm by itself?
thanks for any advise u can give!
FOREIGN GURU
Joined: Jul 2006
Posts: 7,655
Likes: 7
From: Celaya, Gto. MX
Thanks guys for the advice. Would there be any store like autozone/advanced auto/etc that may have a scanner that will read a stroke without me having to purchase one?
i'm still not convinced the pcm is trashed -- i still think i may have some sort of ignition issue somewhere - just not sure where to start troubleshooting it
will the truck even start if the pcm is trashed? should i unplug it and try? don't want to ruin anything internal by doing this
if i have a faulty ignition somewhere (switch, etc), could that still start the motor without properly turning on the pcm?
need help and a starting point besides just tearing it all down and replacing things
anyway to test the pcm by itself?
thanks for any advise u can give!
i'm still not convinced the pcm is trashed -- i still think i may have some sort of ignition issue somewhere - just not sure where to start troubleshooting it
will the truck even start if the pcm is trashed? should i unplug it and try? don't want to ruin anything internal by doing this
if i have a faulty ignition somewhere (switch, etc), could that still start the motor without properly turning on the pcm?
need help and a starting point besides just tearing it all down and replacing things
anyway to test the pcm by itself?
thanks for any advise u can give!
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
I don't think your PCM will work in a Super Duty truck (99 and up). I know your truck won't run with out the PCM. I would start by inspecting the wiring connectors where they go into the valve cover gaskets. Take a very close look at those and the pins in the valve cover gaskets as well. That is a known weakness of these engines.