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3500HD only starts once


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Hi all, I´m new to the forum.

I recently buy a 1999 3500HD cabin and chassis and have some problems with it. I change the key lock and the instrument cluster (Brand new both), it starts ok the first time, but if I turn off the engine and try to restart it, it sputters and die; If I disconnect the battery for about 20 minutes and restart the engine, it runs fine until I turn off again... I´m tired of diconnecting the battery!!.

 

I try to do the relearn procedure for the new key lock, but as soon I turn the key to the run position, the Security lamp only stays on for about 5 seconds and then turn off, so the relearn procedure is impossible to follow.

 

I check the fuel pressure (60PSI), check spark, and both are OK. Any Ideas?

 

Thanks in advance.

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I've had to repair quite a few of the GM passlock setups and the problem is there's about 3 different ways they do it and I don't know exactly what yours is. Did you replace the switch itself or the key tumbler? They are two different things now and the switch is where the goodies are. Also I've seen auto parts tumblers without the needed magnet sent out to me that will never work. You need to have GM parts all the way through. Also you may need to check the wiring. I repared a 95 Z28 that went into security shut down because someone who had replaced the brake switch a few weeks prior pulled on the passlock wires hard enough to expose the ends of the wiring at the plug. Then those crossed and shorted out the resister key circut. I figured it out double checking while waiting on the new switch.

 

If you're in Houston start it up and drive it to my shop. :D

 

Vernon

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Thanks for your advice... I was tired of the problem so I take the truck to the dealer, and they "erase" the old key lock and make the truck start normally (At least they say so), but since then the idle speed is not correct... it oscillates between 500 and 900 RPMs, especially when cold. Do you think it need to "relearn" the idle speed? Or now is the IAC valve? When the dealer scan the PCM they says me the EGR valve is bad, however the check engine light is not on (And yes, the bulb is OK) the EGR can cause that? at idle? or those problems are not related? What do you think? Ah... and No, I´m not near Houston! :cheers:

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The EGR valve could cause it but you're right it would usually set a code. It should relearn things like idle speed within a few minutes of continuous warm idle. Spray some throttle cleaner through the IAC while keeping it running to eliminate clogging as a problem.

 

Vernon

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