Buddy of mine has a 2008 GMC 2500 CC SB 4x4 d-max with about 370k on it. Drove up to the grocery store the other day, and it wouldn't crank when he came back out. All interior accessories still power up, all lights function, ignition cycles, gear selector moves, starter relay clicks and starter soleniod cycles, but it won't crank. We found a cracked driver's side battery neg terminal cable clamp, but it's still making good contact to complete the circuit. Both batteries load tested good and were installed 8/14 with mfr dates in 7/14. All fuses in the box on the driver's fender and under driver's dash side panel tested good, and all the wiring that I can see under the hood and under the truck looks ok. All us oil-burners around here use either the truck stop near the interstate or a local extremely-high-volume gas station to make sure we're not getting bad fuel. Fuel filter was replaced 2 weeks ago and there were no signs of prime loss or air leaks in the fuel system.

It's got a straight exhaust and EFI Live w/ DSP-5 and edge CS monitor from Dmaxtuner.com, so I don't think the tune is the problem.

He had it towed to a shop (general repair, not a diesel shop) locally, and they're baffled after 3 hours of trying to figure it out. Shocking, I know.

Searched here and looks like we need to check to neutral safety switch on the trans, but anyone have any other ideas? Am I missing a fuse box somewhere? Thanks!

 

Did you ever figure this out?

If you dont know there are more fuses on the pasenger engine side firewall.

 

finally got it figured out after about a week of poking, prodding, and testing line resistance. all the fuses were good; turns out it was the ignition switch in the steering column that wasn't recognizing the GM passkey thingie anymore. so, a new ignition switch got thrown in after we threw in the towel trying to figure it out and dragged it to the stealership. apparently several of these trucks in the 200k+ range have been having this problem over the last year or so and when we described the symptoms that was the first thing they tested. purring like a straight-piped kitten now...