Hi guys,
My truck has been pretty reliable until recently, one morning earlier this week I went to start it and the fuel pump did not come on. Engine turned over, WTS light came on -- which from what I understand, means the IDM is getting power. After going through the tech threads, my first suspicion was that the internal fuel pump relay in the CJB had failed. My Fass fuel pump gets power if I wire it directly, my inertia switch is fine, and no blown fuses.

I haven't been able to look at it til today, and here is where it gets a little weird to me. On a whim, I put the key in and fuel pump came on - started right up. pulled it in to the shop, went inside. Came back out - again fuel pump would not come on. FORscan and Autoenginuity both will NOT communicate with the PCM. I can talk to the ABS module, air bags, GEM, that's all fine. but no PCM. come back to it an hour later, truck starts right up, scanners can communicate with PCM.

So at this point, I think my CJB is fine, and I've never heard of a PCM working intermittenly, so that leaves me with a break in my wiring harness somewhere. I wanted to bounce this off you guys to see if anyone has run into this before or has any ideas. I'm thinking the next step is to pull the harness and look for damage/ohm everything out. I just worry that since it's intermittent, I may have a hard time tracking it down.

Thanks in advance for any advice you can give me.


Well, after typing all this up - it just dawned on me that I have a TS6 that came installed when i bought the truck. I never touch it nor do I think about it. I'll pull the chip tomorrow and see if the problem goes away.

Thanks,

Carlos

 

Good call on removing the chip. If you have to pull the PCM to remove it, reseating that PCM connector might clear this up. It's a pretty reliable connector though.

You can try pulling and reinstalling each fuse, especially the PCM related fuses. With these old trucks, sometimes a fuse contact blade will become intermittent in it's socket.

I hear you on trying to find a broken wire - it can be a pain. After the fuses are checked and reinstalled, I'd start by identifying the power and ground wires to the PCM and tracing them out, wiggling them and checking for voltage or continuity with ground respectively.

Good that you have Forscan to check PCM communication - a good clue on if the PCM is alive or not.

 

Dang. That strikes me as odd. Thanks for the detailed description tho!

It could be a specific fuse to the PCM in blown. There are several.

Is the FASS the only fuel pump?

 

The Fass is the only pump, the OE pump has been removed.

So after removing the TS chip, the truck fired right up a couple of times. That's not proof-positive it was the cause -- I'll have to drive it around and see if it happens again. And if it doesn't happen again for a couple weeks, I'll pop the chip back in to see if I can make it no start -- just so that I know with confidence the problem is resolved. Will update in case anyone else runs into this again.

Thanks!

 

Hello all-
new to this forum. I am not sure where to post, but I am having a real difficult time trying to locate a used central junction box for my work truck 2003 F650. Does anybody have any good sources I can call?
Part is YC3T-14A067-GB

Any help would be greatly appreciated. Dave 513 616 8864

 

See any broken solder connections on the chip? Still tin on the PCM pins? Any silicon hiding between the PCM pins?