PCM issues
Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
Likes: 116
From: Saskatchewan Canada
My 2 cents.
I would agree that PCM failure is relatively rare. I have had only one fail and that was on a 98 F150 with the EECV PCM. I was an electronics tech with way too much experience and I have seen my share of leaky electrolytic capacitors, but honestly, I have never found leaky electrolytics in a Ford PCM. Possibly something to do with our climate, but I have no doubt the capacitor failures are real and they can cause quite a variety of problems.
I would agree that PCM failure is relatively rare. I have had only one fail and that was on a 98 F150 with the EECV PCM. I was an electronics tech with way too much experience and I have seen my share of leaky electrolytic capacitors, but honestly, I have never found leaky electrolytics in a Ford PCM. Possibly something to do with our climate, but I have no doubt the capacitor failures are real and they can cause quite a variety of problems.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
But all of the them were out of a 1995 or older Ford trucks.
I have not heard or seen any leaky electrolytics in the 1996 or newer trucks.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
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Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
When the grease drys out in the PCM connector connector after 20 years and water gets in the connector the PCM will let out smoke.
This has happen to a few posters on this site after washing the engine bay with a high pressure washer.
As far as rain or going through a car wash I have not heard of that causing it but driving through high water might.
This has happen to a few posters on this site after washing the engine bay with a high pressure washer.
As far as rain or going through a car wash I have not heard of that causing it but driving through high water might.
Mountain Pass
Joined: Dec 2020
Posts: 109
Likes: 12
So the original PCM is toast, yet in the first post the OP says that two more PCMs were tried. Some possibilities:
- Whatever caused the original PCM to fry went on to fry those subsequent two PCMs as well.
- When the original PCM went out it took out something downstream too (including wiring), and that's now why new PCMs don't fix the problem
- Whatever caused the original PCM to fry went on to fry those subsequent two PCMs as well.
- When the original PCM went out it took out something downstream too (including wiring), and that's now why new PCMs don't fix the problem
Thread Starter
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Cross-Country
Joined: Jul 2021
Posts: 53
Likes: 12
So far, still no solution after several PCM's.
The present status is the engine will run with the SPOUT connector pulled out and the fuel pump relay manually grounded.
There is no ignition with it plugged in.
And no fuel pump activation in either state of the SPOUT connector.
This has been the case on at least 2 of the PCM's we have tried.
Any thoughts out there among the Illuminati?
-Jack (missing my truck in central Texas)
The present status is the engine will run with the SPOUT connector pulled out and the fuel pump relay manually grounded.
There is no ignition with it plugged in.
And no fuel pump activation in either state of the SPOUT connector.
This has been the case on at least 2 of the PCM's we have tried.
Any thoughts out there among the Illuminati?
-Jack (missing my truck in central Texas)
Logistics Pro
Joined: Aug 2014
Posts: 3,559
Likes: 852
So the original PCM is toast, yet in the first post the OP says that two more PCMs were tried. Some possibilities:
- Whatever caused the original PCM to fry went on to fry those subsequent two PCMs as well.
- When the original PCM went out it took out something downstream too (including wiring), and that's now why new PCMs don't fix the problem
- Whatever caused the original PCM to fry went on to fry those subsequent two PCMs as well.
- When the original PCM went out it took out something downstream too (including wiring), and that's now why new PCMs don't fix the problem
Something must be shorted badly.
I had a rat chew my EFI harness at the back of engine, didn't know until I pulled it out.
Swapping computers is not your problem, burned out computer is the effect that something else is causing.
Thread Starter
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Cross-Country
Joined: Jul 2021
Posts: 53
Likes: 12
I could not agree more, Mr. White. Thanks.
The guy who is working this problem for me has already dragged out the harness and is looking for damage.
Sadly so far, everything has checked out, but the battle rages on...
The guy who is working this problem for me has already dragged out the harness and is looking for damage.
Sadly so far, everything has checked out, but the battle rages on...
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
Sounds like no power to the PCM.
Check for power at pins 55, 71 an 97 of the PCM.
If no power at pin 71 & 97 check that power is leaving the PCM Power relay pin 87 with the key in the run position.
The wire #361 may be open between the PCM Power relay and the connector of the PCM.
Check for power at pins 55, 71 an 97 of the PCM.
If no power at pin 71 & 97 check that power is leaving the PCM Power relay pin 87 with the key in the run position.
The wire #361 may be open between the PCM Power relay and the connector of the PCM.