Electrical Problems


New member
Nov 24, 2022
I recently replaced the injectors on my 04 lb7 and removed the cab to do so. I did a bunch of work to it when I had the cab off, but after putting it back to gather it ran well but it shift indicator no longer worked. When I test drove it shifted hard in 1st but ran fine other wise. I parked it for a week, when I put it into drive it clunked but didn't move. I changed the neutral safety switch and it did nothing. I pulled the codes p0700, p0802, p0090, p0193, p0335, p0540. I figure one of the modules isn't working. I cleaned all the grounds, but don't know how to check proper voltage and grounds. I just need somewhere to start. I have charged and tested my battery's. checked over the wiring harness didn't see any obvious issues.

Ron Nielson

Active member
Oct 11, 2009
Berryton, KS
Scroll down to the bottom and enter your DTC and Chevrolet

https://www.dtcdecode.com/Chevrolet also check here

Checking for power/ground is like checking battery voltage - one probe on the + side, the other on the - side. Of course, you have to know which side is which. Go to https://www.gmupfitter.com/wp-content/uploads/2021/05/2005_LD_CKFullSizeElectrical.pdf and download the wiring diagrams and lots of additional electrical info


Sep 20, 2018
And you need a better scanner. The p 0700 code is from the ecm, but the actual code is stored in the tcm. You need to be able to read the tcm codes.