How do I check the PCM power ground - Ford Mustang Forum

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post #1 of 3 (permalink) Old 12-20-2010 Thread Starter
enfermo's Avatar
Joined: Jan 2009
Location: ventura
Posts: 39
How do I check the PCM power ground

2000 4.6L GT- Got some cash and I am going back in!!! I need to get this running!

Awhile back my car wasn't starting after I did some necessary work on it (still isnt, has been sitting ) and you guys suggested I check the PCM power ground.

I am learning as I go(new very little about cars) and you guys here have really helped me. So far I have changed the coils, spark plugs, fuel filter, and intake manifold; thanks to your help.

After that main project, my car wouldn't start. I guess it might be a fuel pump issue but I am going to go over the little stuff you suggested. So what is a PCM power ground, where is it, and how do I check it?

I did a trick to see if its electrical that my brother in law showed me. I turned the key and he put a screw driver next to coil or spark plug(dont remember exactly) to see if there is a spark. There was. I dont know where this fits with everything. We also did a fuel pressure test where we disconnected a fuel hose( I believe its the one that connects to the fuel rail) in the engine bay to see if gas came out when cranked, none did. Thats why I am leaning to all of this hopefully coming down to a new fuel pump.

Here is my old thread for anyone who remembers or wants more info.

If anyone has any good mechanics to refer me to in Ventura County, CA that would be awesome.

Black Mustang 2000 GT Convertible
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post #2 of 3 (permalink) Old 12-20-2010
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kregalmach1's Avatar
Joined: Dec 2009
Location: Petersburg
Posts: 197
try to help you

if no fuel is comeing out when the key is turnned on be sure to listen for the pump to kick on you should hear it but you can have some one listen in the fuel filler door if you hear it then check fuel pressure before the filter youll have alot of presure if not then its almost working and not working well enough member to check after the filter again too but be sure you have power to the pump as well

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post #3 of 3 (permalink) Old 12-20-2010
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wmburns's Avatar
Joined: Sep 2010
Location: Houston
Posts: 6,239
Let's get back to basics. Have you CHECKED all of the fuses in the engine bay and driver's kick panel?

Is the battery fully charged and are the terminals clean, corrosion free, and tight? Do not cut corners with regards to the battery and charging system. Today's cars will not run right without a strong battery, good cables, and clean grounds.

It's not recommended to test the spark by grounding with a screw driver. Today's ultra high voltage ignition systems can be damaged by arcing.

Turn the key on but do not crank. Do you HEAR the fuel pump prime for 3 seconds? If not, STOP and find out why. The car will never start if the fuel pump does not prime.

If the fuel pump does not prime, test for +12 volts at the trunk IFS switch. If no voltage, the problem is with a blown fuse, CCRM, or wiring.

If voltage is present, the problem is a bad fuel pump, bad FPDM, or bad PCM.

Post the results of the tests and will go from there. Again, it is vital that all fuses are good and the battery is good.

Good luck.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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