hello all again, i had a string of posts a few weeks ago about low volts on + side of coil and short in wire, my boys truck was running for a while and then it quit and will not restart now again, we had what we thought was a short in the wire from icm to coil, a little recap, couldn't find a bad component and when we got the harness all opened up, we were good to go, it ran fine, started right up, couldn't find a bad spot in the wire or nothing, but when bunched up the wire from coil plug back into main harness it would cut out, open that small chunk where the coil pigtail splits out, and it was fine. well, now not so much. last time i could run it by jumping from battery + to coil + with a jumper wire and it would start right up and run, tried that yesterday and when i jumped to the coil +, i powered up the fuel pumps, so it seemed like i was bypassing ignition switch just by running a jumper from battery + to coil connector + side, this was with the ignition key off. that seems very odd. can someone with more knowledge of the ignition wiring tell me where i should be looking for a short? could i have a bad grey dizzy mounted ICM module? or should i start looking at the PCM (computer)? the ICM appears to be a junk yard special, it is a motorcraft, but it was from a junk yard and i have no idea what its history was. any thoughts guys? just for recap, just few weeks ago, but in a new ignition switch (actual electronic part), new coil, new EEC and Fuel pump Relays.
thank you very much.
Micheal

 

It is normal for the fuel pumps to start up when you put a hot wire on the + side of the Ignition Coil as you are also powering the PCM Power Relay and that relay is powering the PCM Computer along with the coil to the fuel pump relay.

Sounds like you might have to adjust the Ignition Switch or the Ignition switch may have a bad plug.
The ICM may have been bad at the salvage yard also and that may be why the truck was in the salvage yard.

 

thank you very much Subford! it is warming up now a little, so i should be able to look at it a little bit. i will try adjusting the switch module a bit and also will probably replace that ICM with a new one and try that. got some more troubleshooting to do, i was just worried that something was shorted when i hooked a jumper up and powered up the fuel pumps, that something was amiss, it probably was amiss last time as i don't remember having the fuel pumps spin up last time i jumpered it. when one adjusts that ignition module, does one just loosen it slightly and slide it one way or the other and see how it works or is there a specific method for it? thank you again!
micheal

 

Just slide it one way or the other and see how it works. You should be able to crank the engine and have battery power at the + of the Ignition coil in the run position. The ACC position should power the radio also.

 

thank you very much! i will give it a try and see what i can do with it.
thansk again.
micheal