Ignition Switch wont fix my problem - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 7 (permalink) Old 05-16-2011, 04:10 PM Thread Starter
Join Date: May 2011
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Ignition Switch wont fix my problem

Hi everyone I am new here and am in need of help please!

I have a 2003 chevy silverado 2500 HD duramax LB7

I have been having electrical problems for the last 2 years and have not been able to figure it out. The first time I knew that something was wrong I was driving down the highway at normal speeds and the truck completely died engine and electrical. I was able to put the truck in neutral and cost to the shoulder, I put the truck in park took the key out and then put it back in and started the truck and it ran fine. I should mention that the key was out for several minutes as i was freaked out and made a few phone calls. The truck ran fine for the next few months, then while I was in the mountains hunting at the end of November driving down a two track road at night the same thing happened, truck completely died engine and electrical. This time I stopped the truck took the key out and restarted it and it worked fine. I should also mention that somewhere along the line my cluster died so I had to get it replaced. Over the next 6 months the truck worked fine.

The new most recent problem (intermittent over the last 9 months or so) is when I start the truck when it is warm, after filling it with diesel or running into the store for something, the truck RUNS but the gauges do not work the security light stays illuminated, the radio does not work, the windows do not roll down and the prindle under PRND321 is not illuminated. I turn the key to the off position and remove it the restart the truck and everything works fine. This seems to happen two or three days in a row then is absent for a while, just long enough for me to forget about it, then the same problem repeats itself.

I know that most of you will read this and assume that the Ignition Switch needs to be replaced. That is the same thing my mechanic friend told me would fix this problem. I installed a new ign switch and the truck worked fine for a month or so then the same problem showed itself again. I figured it could have been a faulty part so the other day I replaced the ign switch again. The first start everything seemed to work fine, then I went to the gas station and after filling the truck I started it and the same problem was back. On both of the new ign switches i was sure to align the gears the same as the oem ign switch. I have also replaced the cluster.

I have also tried disconnecting the batteries to reboot the PCM.

I am very confused and am in need of some help, I have not been able to find any helpful things already posted on the internet so I am seeing if anyone on here has had the same problem or have any other ideas.

Thanks for the help.

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post #2 of 7 (permalink) Old 05-16-2011, 05:41 PM
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Do you have any mods done-- or have a tuner-? You should fill out your signature with the info-- that will help. [User CP center top bar]

Take the under hood fuse box cover off and inspect the wires under the fuses. Sometimes mice make a next there and cut up the wires-- then they short.

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post #3 of 7 (permalink) Old 05-16-2011, 06:12 PM
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Have you had the codes read yet? Also, most of the components you mentioned as acting up, have inputs from the body control module, if I recall correctly. Have you had that tested? I would suggest a scan and see what turns up? If nothing turns up, it could just be an intermittent connection (i.e. Fuse box as previously suggested, or the PCM or the BCM, etc.) However, if that is the case, there should be be a loss of signal code stored.

There is also a maxi-fuse located in the main power lead up by the bulkhead. It that fuse or connection is intermittent it may cause a complete failure as you described. Last but not least a chaffed wire shorting could cause a similar problem. Check your harnesses for chaffing, especially where they pass by sharp corners (e.g. Alternator Bracket, etc.) Your symptoms of stopping and then restarting after an apparent reset of the PCM is typical of a short casue by a wire chaffing.

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post #4 of 7 (permalink) Old 05-17-2011, 03:25 PM
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I would pull the cover off around the steering column and shifter follow the wires up to the ignition switch. There is a black plastic cover over the connections. Pop the cover and look at the terminals. I seen a bunch of them melted just enough to make it act weird. Plus if it shuts off you can wiggle the harness around.
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post #5 of 7 (permalink) Old 05-17-2011, 06:18 PM Thread Starter
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I have checked for codes multiply times and have not found any in either the body control module or engine.

I will check under the fuse box for loose connections, corroded wires, or melted/chaffed, and let you know what I find.

I have looked at the wire in the steering column and have not seen anything that looks out of the ordinary.

Thanks for your help I will let you know what I find.

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post #6 of 7 (permalink) Old 12-08-2011, 09:56 PM
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must not have found anything...


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post #7 of 7 (permalink) Old 12-09-2011, 03:24 PM
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check where the wire bundle goes though the firewall, I have had issues there

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