Okay. this might get long winded but ive been having some electrical issues with my truck its an 01 7.3, 257k, completely stock except for straight pipe and wicked wheel. my issue started about 2 months ago when it had a crank but no start issue, after throwing a CPS, and IPR at it it ended up being the IPS. after the IPS was changed it fired right up and i was back to the races i also did every test my scanner would allow me to IE. buzz and cylinder contribution all checked out great and no more codes were present. fast forward a month the truck lost half of the motor while driving, absolutely no power and shaking like a pit bull crapping peach seeds. i dug into the left bank as my scanner told me to and found that the truck had some plastic wedges in the plug for the UVCH which was in turn forcing the plug to separate from the harness. i cut a quarter down jammed it in there and again i was off to the races. truck ran great for 3 more weeks then left me stranded with the same issue except now i have a P1670 code which tells me the PCM and IDM arent talking to one another the truck would still start and run it just ran like crap no power ect. . . two days later when i had time i go to do some tests and now i dont have a wait to start light and the truck wont start at all. i have checked all of the relays and fuses they are all working and no blown fuses at all, i also took it right in the prison wallet and threw a new IDM in it. obviously that didn't work either. my parts cannon is getting low on ammo. can anyone shed some light on my issue? any help is greatly appreciated.

 

 

I haven't checked the fuel bowl heater, however the fuse was in tact. I checked the fuses with a test light and by pulling them 1 by 1 and visually inspecting them.

 

I ran into an issue not long ago with a cracked fuse and an led test light. Fuse would show good until a larger load was placed on it. Once that happened, it would open. Also, on my truck when it blew the fuel bowl heater, it was not the small fuse but one of the larger mega fuses that blew.

 

 

I just checked all of the fuses with my multi meter and they all showed continuity. The only way I know to test the relays is to swap them with the horn relay. They all worked. I've torn apart what I can of the wiring harness and I can't find any chafed wires. Getting close to parking it in the street and setting it a blaze.

 

Are you using OEM sensors? Aftermarket sensor have proven to be a problem for us. Do you have the ability to scan your sensors? It's essential and a lot better than tossing $$$$ at it hoping to find the problem.

 

 

All OEM sensors. And the fuel bowl heater didn't make a difference. Unplugged it swapped the fuse and still no go

 

I'm starting to wonder if the PCM is toast

 

Does it have fuel in it? Does it have oil in it? What are you using to read your codes? A lot of readers won't work with these trucks.

 

Fuel and oil are good. I'm using a snap on solus to read codes. I don't known if low fuel or oil will prevent the WTS light from coming on

 

Not sure if this will help but here is the wire diagram for PCM power. 2 Fuses and a relay involved. There is also a diode inline with power to the energize circuit for the PCM power relay. You can check for power at several points. As you can see power also goes to AIH relay, glow plug relay, IPR, etc. A short in one of these components could cause a problem.

 

Under hood fuse panel. 24 is PCM power fuse, 30 is PCM power relay, 37 is PCM power diode

 

Well damn. I went and checked my truck and still no WTS light. So I figured I would check all of the sensors i could see, separated the wires, checked for bare wire, and I pulled the PCM diode just to look at it and see what it looks like and plugged it back in. Low and behold the damn light is back on and I have no idea which sensor I messed with that made the change