Ford Repair Questions? Ask a Mechanic for Answers ASAP
Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner till early morning.
To diagnose this concern you have to unplug all things that get the 5 VREF. Then see if the 5 volts are back. If so then it is one of the sensors to blame. IF the voltage is not back then cut the vref wire after the pcm. If there is still no voltage then it is the PCM to blame.
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Thanks for using Just Answer, Chris
Time for a new PCM as long as all the powers to the PCM are good, which I assume you meant when you said the computer seem to be working.
How are you taking your resistance reading Ex: PCM unplugged testing a ground wire at the PCM to the ground terminal on the battery?
Here is a diagram. https://dl.dropboxusercontent.com/u/90220402/SEPCM.pdf
All PCM grounds should show 0.0 reading. You may want to clean the engine, and body grounds from the battery. Even at 6 ohms it still pretty much a good ground.
You're still getting no 5 VREF to sensors?
If you OHM test the PCM ground wires from there connection on the vehicle to the battery is there resistance there as well?
Using a scan tool is the PCM getting a cam and crank sensor signal when cranking?
I need to know if you have a 2 or 4 valve engine?
Hello again Chris here,
pin 3, 24, 25, 51, 76, 77, 103 ground
pin 55 power all the time
pin 71 power with the key on
If all powers and grounds are good, the VREF wire is cut and not providing 5 volts out with the key on then it has to be the PCM.
So what I gather from your list.
There is no ground on pins 25, 77, and 103?
There is no power on 71?
I can not make since of your replies. 71 is empty, 71 has power?
Are there pins on the PCM for pins 77-103?
Are you sure your looking at the diagram correct by matching the wire colors to the pins?
Other than the PCM missing some grounds then all looks within specs.
I have carried this as far as I can. I can opt out and let another help.
Opting out now, best of luck
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