2002 Gmc Sierra Starting Problem

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Have a weird issue with my 2002 GMC Sierra. It's a 4.8L, 4x4 automatic if this helps.

 

I've only had the truck for about two months and once in a blue moon it won't crank when I turn the key to start it, just dead silence. All the lights come on and it acts like it's getting power to eveything until I try to crank. If I pull the shift lever through the gears and back to park and giggle the 4wd handle it starts fine. This happened a few times and has been getting more frequent.

 

Then yesterday I started it up and moved it to unload some lumber, turned it off and then it wouldn't do anything and none of my usual things seemed to fix it. Fuses are okay, battery if fine, swapped the relay and nothing. When I jumped the starter by running a jumper cable from the positive terminal of the battery to the smaller connector on the starter selonoid, it started right up and I drove it back to it's usual parking spot in the driveway and parked it. Now it seems to be starting fine again.

 

Any ideas what could be wrong. I was thinking either neutral safety switch or ignition switch...but...if it was the neutral safety switch wouldn't it just be able to start in any gear, not just park? Or, if it was the ignition switch, how come all of a sudden it seems to be working?

 

Any help would be greatly appreciated.

 

Caleb

[Doug_Scott]

My guess is neutral safety switch. You are using the wrong logic when you think about the switch. When it fails, it may just fail to see park or neutral, so no start. The switch thinks the vehicle is not in park or neutral. The fact that you used to be able to wiggle the shifter to get it to start points at the neutral switch.

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I took the connections off the starter and cleaned them and it worked great for a few days, now it's back to it's same old tricks.

 

I had my wife turn the key while i held the voltmeter to the starting terminal on the starter and am getting the proper voltage. I assume this rules out the ignition switch??? The gear shift trick does nothing any more, and if I jump the terminals on the starter it will start and be fine for a few stops, then act up again. Could it just be my solenoid is on it's way out?

[f7pilot]

I took the connections off the starter and cleaned them and it worked great for a few days, now it's back to it's same old tricks.

 

I had my wife turn the key while i held the voltmeter to the starting terminal on the starter and am getting the proper voltage. I assume this rules out the ignition switch??? The gear shift trick does nothing any more, and if I jump the terminals on the starter it will start and be fine for a few stops, then act up again. Could it just be my solenoid is on it's way out?

[markw8]

Time for a starter? Also check the condition of the battery cables from one end to the other.

 

Mark