I've been having starting problems with my truck. Replaced the Glow plug relay with the Stancor relay, checked all glow plugs (.5-.6 ohms) and everything seems in order. I rebuilt the fuel bowl due to a leak from the drain valve and replaced the fuel filter. Had a hard time starting it again this morning, but it eventually started. Once running it runs fine (no missing, surging, etc). Drove it ~20 miles and shut it off in the garage. Now it won't start. Before starting and with the key in the run position, I can hear the fuel pump running and it eventually times out after 20-30 seconds. Been working on the issue for the last 2 weeks (it's not my daily driver).
I borrowed a Star tester and got the following codes:
P1298 IDM Fail
P1670 Elec feedback signal not detected
P0603 PCM KAM test
P0605 PCM ROM test error
P1668 PCM-IDM Diag Comm error
The research that I've been able to find so far says that these error codes are due to the programmer (Superchips) and the IDM resistor mod. This truck only has 75k miles on it and has been problem free up until now. Anyone have any suggestions?
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How does is start when it's already at operating temperature? Have you returned it to stock programming to see if that makes a difference?

 

Thanks for the reply.
After it was warm this morning I tried to re-start and it wouldn't fire. I've since gone back to the stock programming with the same result...no start. Also, checked the IDM relay and fuse (both were good). Going back to the stock program reset the codes. The only code I get now is P1670.

 

It *could* be a bad IDM, but it could also be a chafed wire somewhere. I'd start checking wiring harnesses for any signs of chafing, especially where the engine harness passes over the left valve cover. Can you clear the current codes, then run a KOEO test and see what codes that shows?

 

I checked the harness as you suggested and couldn't find anything wrong. Got my hands on an IDM module and that fixed it. Started up multiple times, took it for a ride without any issues. Thanks again for your suggestions.