Stuck PCM Connector
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Again with the keys out of the ignition there is no power applied to the PCM or the injectors. I agree nothing else controls the injectors that's why this whole scenario makes zero sense.
If the ignition switch is out of adjustment/stuck I could see potentially how the EEC relay could get energized which in turn would apply power to the PCM, injectors, and ignition/start circuit. Assuming that EEC relay is energized and if the computer was bad and causing injector #2 to turn on continuously that would also mean injectors 3,6 and 7 would also be triggered on since the PCM uses the same ground line to fire all 4 injectors.
Electronic Engine Controls Diagram 24-1
Electronic Engine Controls Diagram 24-2
So getting the PCM out is not the only issue you have to troubleshoot here. Granted it should be an easy task, but be aware there is a bigger iceberg under the surface of the water here.
If the ignition switch is out of adjustment/stuck I could see potentially how the EEC relay could get energized which in turn would apply power to the PCM, injectors, and ignition/start circuit. Assuming that EEC relay is energized and if the computer was bad and causing injector #2 to turn on continuously that would also mean injectors 3,6 and 7 would also be triggered on since the PCM uses the same ground line to fire all 4 injectors.
Electronic Engine Controls Diagram 24-1
Electronic Engine Controls Diagram 24-2
So getting the PCM out is not the only issue you have to troubleshoot here. Granted it should be an easy task, but be aware there is a bigger iceberg under the surface of the water here.
Thread Starter
|
4wd Low
Joined: Feb 2009
Posts: 12
Likes: 2
Again with the keys out of the ignition there is no power applied to the PCM or the injectors. I agree nothing else controls the injectors that's why this whole scenario makes zero sense.
If the ignition switch is out of adjustment/stuck I could see potentially how the EEC relay could get energized which in turn would apply power to the PCM, injectors, and ignition/start circuit. Assuming that EEC relay is energized and if the computer was bad and causing injector #2 to turn on continuously that would also mean injectors 3,6 and 7 would also be triggered on since the PCM uses the same ground line to fire all 4 injectors.
Electronic Engine Controls Diagram 24-1
Electronic Engine Controls Diagram 24-2
So getting the PCM out is not the only issue you have to troubleshoot here. Granted it should be an easy task, but be aware there is a bigger iceberg under the surface of the water here.
If the ignition switch is out of adjustment/stuck I could see potentially how the EEC relay could get energized which in turn would apply power to the PCM, injectors, and ignition/start circuit. Assuming that EEC relay is energized and if the computer was bad and causing injector #2 to turn on continuously that would also mean injectors 3,6 and 7 would also be triggered on since the PCM uses the same ground line to fire all 4 injectors.
Electronic Engine Controls Diagram 24-1
Electronic Engine Controls Diagram 24-2
So getting the PCM out is not the only issue you have to troubleshoot here. Granted it should be an easy task, but be aware there is a bigger iceberg under the surface of the water here.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
That is my point here. This theory the PCM is bad and turning on only injector #2 is so bizarre and highly unlikely in my opinion. It would take a lot of stars and planets to align to get this all to come together. Now that you have the PCM removal issue going on you are now committed to following through to verify what the inside of the PCM looks like. Once you get that taken care you have to verify if power is really getting applied to the EEC relay with no key in the ignition, or simply turned to the Off position. If there is no power you get led down a bunny hole.
There is another path for power to the PCM via the Keep Alive Memory (KAM) circuit. It's only purpose in life is to keep the memory alive for stored codes and other info about key sensors. I suppose if water got into the PCM or PCM connector it could short power to an injector but there is no ground path applied so yet another miracle of getting power and a ground path to a single injector is a stretch for anyone's imagination.
There is another path for power to the PCM via the Keep Alive Memory (KAM) circuit. It's only purpose in life is to keep the memory alive for stored codes and other info about key sensors. I suppose if water got into the PCM or PCM connector it could short power to an injector but there is no ground path applied so yet another miracle of getting power and a ground path to a single injector is a stretch for anyone's imagination.
Thread Starter
|
4wd Low
Joined: Feb 2009
Posts: 12
Likes: 2
That is my point here. This theory the PCM is bad and turning on only injector #2 is so bizarre and highly unlikely in my opinion. It would take a lot of stars and planets to align to get this all to come together. Now that you have the PCM removal issue going on you are now committed to following through to verify what the inside of the PCM looks like. Once you get that taken care you have to verify if power is really getting applied to the EEC relay with no key in the ignition, or simply turned to the Off position. If there is no power you get led down a bunny hole.
There is another path for power to the PCM via the Keep Alive Memory (KAM) circuit. It's only purpose in life is to keep the memory alive for stored codes and other info about key sensors. I suppose if water got into the PCM or PCM connector it could short power to an injector but there is no ground path applied so yet another miracle of getting power and a ground path to a single injector is a stretch for anyone's imagination.
There is another path for power to the PCM via the Keep Alive Memory (KAM) circuit. It's only purpose in life is to keep the memory alive for stored codes and other info about key sensors. I suppose if water got into the PCM or PCM connector it could short power to an injector but there is no ground path applied so yet another miracle of getting power and a ground path to a single injector is a stretch for anyone's imagination.
Finally got the thing started, but I had to hold the pedal to the floor, be and it was running rich, and rough.
Pulled the dipstick, and it’s way over full. Drained the “oil” and it had three extra quarts of fuel in it.
Stuck injector on cylinder two made complete sense. Well sense I have to tear the upper plenum off, might as well replace all eight.
Bolt everything back up. Truck starts and runs perfect. Dad takes it around the block, and it’s back to normal. Then, we are standing there, and I hear a rapid clicking sound. Pop the hood…smell gas…then see smoke coming from the number two injector. I yank the negative battery cable and it all stops. Reattached the cable, no sound. Went to start it up…hydrolocked.
Pulled the number two plug, turned the engine over, then replaced the plug. Won’t start. Hold the pedal to the floor and we are right back to the beginning. Running rich and rough.
The battery light is on the whole time, and stays on when you turn the key off and remove the keys from the ignition. So there is power being applied somehow.
I really appreciate your well thought out responses. Thank you very much for helping
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Now you have more evidence the ignition switch is probably the biggest contributor to your issues. As you peel back the onion you will see what triggered this chain of events.
Ignition Switch Testing procedure:
Ignition Switch Testing procedure:
Thread Starter
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4wd Low
Joined: Feb 2009
Posts: 12
Likes: 2
Ok, I’m going to this tomorrow. I’ll let you know
Thread Starter
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4wd Low
Joined: Feb 2009
Posts: 12
Likes: 2
Brother I can’t thank you enough.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
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