Swapping out PCM question

[johngeorge]

After many hours of ohming wires and checking circuits I have concluded I need a PCM. My question is: Which of the numbers on the PCM's need to match? Mine are as follows:

Motorola SN: 6FXF25N016S9
Motorola Model: 6FXF25NA32
Ford P/N: 6L1A-12A650-KB
Supplier: Motorola M799G

PCM U222 GNV1 5L28

Also curious as to whether anything has to be done about the PATS when swapping a PCM.
All advice greatly appreciated

 

[stamp11127]

Ford P/N is the one you need. PCM's are tied to the instrument cluster for the pats - need to program or get a tuner and turn the pats off.

What makes you thing the pcm is the problem?

 

[johngeorge]

No fire at cyl 3 COP. I rigged up a tester using an old COP and plug. I grounded it and connected it to the #5 COP connector and the plug was firing. I did the same with #3 and no fire. I ohmed the Signal side of the circuit and it was the same as the rest. No resistance between the COP connector and the pin at the PCM on the signal side. No continuity at all between the COP connector and battery negative with the PCM unplugged which tells me there is no short to ground. Plug the PCM back up. KOEO and I have 110 ohms between signal side and battery negative on #3. The other 7 all show 425 ohms. Key off, the other seven all show no continuity and #3 shows 95 ohms. Also I can use an LED test light on the #3 COP connector. I connect the neg clip to signal side and the Pos probe to 12V side. The light flashes while engine idles. No fire under a load though. If there is something else I can check please let me know. Thanks

 

[toms89]

The pcm controls the grounds to fire the coils. So if you disconnect the pcm there would be no ground. B+ voltage should be present at all coils when the ignition is on. You should notice all the B+ wires are identical in color and common where as the grounds all are different.

That said your logic seems sound to me. Does seem to indicate a pcm driver.

 

[johngeorge]

Update: I cut the signal (negative) wire to the coil. I cut it about an inch or so from the PCM connector and the same at the COP connector. I scabbed in another wire. Now when I use my homemade tester of a spark plug and COP I can see the fire jumping across the plug while the engine is running. When I reconnect #3 COP that cylinder is still dead. I swapped the #3 COP with the COP I used for my tester and still nothing. How do I check the injector to see if it is working properly? Also, now when I ohm the signal side of any of the coil connectors I get OL with KOEO. Everything seems to ohm out ok.

 

[Msport]

Take a look at this link:

Testing Fuel Injectors Procedures from You Fix Cars.com

 

[stamp11127]

Check the plug for the #3 COP. You may have a broken pin inside.