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Hey guys, so I got this bright idea that I should move my PCM inside the cab to clean up the engine bay a lil. In order to do that I had to take the wiring harness off, move the PCM and then reinstall the harness. After I put all the wires where they go and try to start the truck nothing!
I turn the key to the ON position and the fuel pump kicks on to build pressure and shuts right back off (as usual). Now heres where it gets wierd. I wired up a push to start button so when I push the button the motor cranks. However, my fuel pump wont kick back on and Im not getting spark. Obviously the PCM is not aware that the motor is being cranked since I basically "Hot-Wired" the starter. I looked through all the schematics and PCM pins to see if missed something but I cant find anything. I did my own harness and Allen took off the VATS about a year and half ago. The truck was running fine till I decided to get into this. My question is: How do I get the PCM involved in starting procedure cuz Im sure thats problem. Any advice or ideas will be greatly apreciated.
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Hmm... I would imagine there's a voltage signal that tells the PCM that the ignition key is in the START position.
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Have you tried bypassing the switch to see if it will start?
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The remote start button, don't you have to turn the ignition switch "on" before pushing the button to start the truck? I wired a remote start button so I can bump the starter when under the hood. It is independant of the PCM so it will not start the truck when bumping the crank around. I'm not quite sure what you've wired it into and what your goal is. A little more info please.
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When you turn the key to the ON position everything works fine and all the PINK wires get power.
When you turn the key to the START position your YELLOW wire gets power and it goes to the starter relay which then sends power to the PURPLE wire to the starter. So what I did was, instead of having the ignition switch send power to the YELLOW wire, I got a push to start button.
When I hop on the truck I turn the key ON and going all the way to the START position I just hit my PUSH TO START button. Like I said the thing cranks it just wont fire up. I really think its got something to do with the PCM. I dont see how it could be the wiring cuz I really didnt change anything besides the starting switch but that shouldnt matter. I just wanna know if theres wire that signals the PCM that its time to start, if so what pin is it?
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Did you remove your ground wire while relocating the harness? It sounds like you lost power, blew fuses or something while moving the PCM. Nothing in the PCM receives a start signal. The PCM gets constant 12V power and switched 12V and that's it. Try just running a jumper over your push to start switch so that the key starts the truck again. Maybe the yellow wire does more than just send signal to the starter relay.
