SOLVED! Cranks no start

Swisscheese31

New Member
I have been a lurker in the shadows absorbing all information I can but don’t have much to help anyone. My problem with my 2003 LT with 157,000 miles on it is it cranks but won’t start.
At first we decided that the fuel pump went. The relay was good but pump wasn’t charging. So I changed that out yesterday. No codes were present on my reader. But it didn’t fix the problem of course!
Checked the relay again that’s still good so started to check the panel. The relay gets juice but the panel isn’t sending it out to the pump. Jumped the panel and the pump charges but still won’t start. Checked codes again with another reader and these came up in this order:
C0235- rear wheel speed signal circuit open
U1000- no state of heath from module
P1682- ignition 1 switch circuit 2
Any suggestions? Should I replace the ignition switch or start chasing grounds first??
 

MRRSM

Lifetime VIP Supporter
Welcome to GMT Nation...

For the “C0235- rear wheel speed signal circuit open” issue:

https://www.2carpros.com/questions/2004-chevrolet-trailblazer-rear-wheel-speed-sensor

ANTILOCKBRAKES1.jpgANTILOCKBRAKES2.jpgANTILOCKBRAKES3.jpg

For the “U1000- no state of health from module” issue:

https://gmtnation.com/forums/threads/3-communication-errors-u1000-u1021-u1045.8939/

For the Proper Ignition Switch Diagnosis-Solution and Use of Ignition Circuit Diagnostic Schematics:


Please...If necessary… Stick with performing the R&R with the ACDelco OEM Ignition Switch.
 
Last edited:

aaserv

Well-Known Member
For Gods sake don't go throwing more parts at it. That code does not mean your ignition switch is bad. For half the cost of the fuel pump you could have had it properly diagnosed. All those codes are rather generic but they do all indicate a possible grounding problem. Ck all the grounds, if you cant find anything there get a proper diagnosis ....
 

Mooseman

Moderator
Although we do not usually recommend the parts shotgun, the ignition switch is relatively cheap and easy to replace and is a regular failure part that has since been updated to a more durable version. It's also easy to diagnose as per the video.
 
OP
OP
Swisscheese31

Swisscheese31

New Member
Thank you for the information and diagrams. The fuel pump turned out to be a necessary fix as the 2 metal lines on top were corroded and about to break off in due time. We ended up chasing the grounds which were ok but found The PCM 1 fuse had blown. Which we had checked visually yesterday (tired and lazy- should’ve used a tester!) Replaced it and started right up and seemed fine. So we cleared the codes; Turned off and went to daughters hockey game. Came home started up again to check it and is running rough with check engine Iights on. Has a p0306 code. Deal with that misfire tomorrow after hockey all day!!
 

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