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Wiring Diagram 2003 Duramax

29K views 6 replies 5 participants last post by  Coghlin 
#1 · (Edited)
How do I get a wiring diagram for a 2003 Duramax? or a logic diagram of sequence of events that need to happen for the truck to allow a start condition.

We are trying to troubleshoot a no start. It does not even try to turn over. It is like the computer is preventing the truck from being started. The truck was running and it seemed like the alternator quit and then it kept losing voltage and then the motor started to knock so we shut it down. Now no start or even try to start.
 
#3 ·
will it start if jumpstarted? connections at the battery?
 
#5 ·
Figured it out. Was pretty simple. No it would not start even boosted and the codes it threw didn't really mean anything. It was weird you couldn't even turn the key off. Some dash lights would stay on.

Anyhow,

One of the battery cables became loose so that battery wasn't getting charged. Then it got real cold and because the battery was not properly charged it probably froze. This caused the battery to have a short in the cells. Then the truck was put in the shop for the night and was thawed out before a trip. Then we figure the one cable was making intermittent contact causing the alternator to work very hard and fried the alternator trying to charge the bad battery. Then when the alternator quit the truck eventually lost too much voltage with the one battery. Then when we tried boosting it we noticed the one battery cable a little loose and tightened it. This caused us to not be able to boost the truck because the battery was shorting.

Replace the one battery and alternator and all is well. Truck was sure acting weird though. Hopefully someone can learn from this. Thanks for the replies.
 
#6 ·
coghlin if the other battery is more than a year old i would do 2 new batts
just my 2 cents
 
#7 ·
It was my Dad's truck (my old one). The battery was only a couple months old.
 
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