Ignition/starting problem

Psheldon · September 29, 2006

I have a 1993 GMC Sierra that has a wierd problem. Occasionally it won't start. you can turn the key and get power to the instrument cluster, lights and radio, but when you turn to crank, nothing. No click of the silenoid, no crank of the starter. I have already had the starter replaced, Have tried disconnecting the Neutral saftey switch to check it out. I've had it happen cold, hot, with the A/C having just ran, With it not haveing the A/C just run. I can sometimes wiggle the Gear shift and get it to start, sometimes it does nothing. Sometimes just trying to start it several times it'll finally kick over. sometimes it'l run for months without happening, other times it'll happen several times in one day. I'm lead to believe I have a loose connection somewhere between the ignition switch and the starter, as it will start working again after being towed, but sometimes just letting it sit for a few hours will let it start again. Any ideas of what to look for or check would be much appreciated, right now anything helps.

Thanks

tasturbo86 · September 29, 2006

Switch/wires is a good place to look.

It is also possible that the solenoid is bad and never tries to move/engage.

I would put a meter on the small wire at the solenoid and see if you get 12v EVERY time you turn the switch. If you always get 12v, I would throw the solenoid away. If you sometimes don't get 12v, throw the switch away.

On second thought, check for poor connections before you actually throw anything away. I almost bought a starter until I found a loose spade connector.

GM-Tech · September 29, 2006

Hook up a voltmeter to the solenoid and see what kind of voltage you're getting there when this happens. If it's at least 10 VDC, that's ok, work your way back. See if you're getting 10-12 volts to and through the neutral switch and then see what you're getting out of the ignition switch. If you do have at least 10 VDC right at the starter, then it's a starter problem.

Does it have an aftermarket alarm? We've seen tons of problems where they cut the starter feed at the ignition switch so they can interrupt the starter when the alarm is activated. The connections are often crappy and practically fall apart when touched. So, not enough current can get through to operate the starter.

Psheldon · September 29, 2006

alright I'll trace back the wires. It doesn't have an alarm, and I'm pretty sure it never did. I'm just not looking forward to messing with the wiring harness. The biggest problem I have is it never seems to break at home always somewhere else, then fixes itself by the time I get it home, so it never seems to happen when I have the tools and time available to mess with it. I'll give it a shot with it working, maybe I can find a loose connection or cut wire.

95Sierra2500 · September 29, 2006

Is this truck a manual? If it is, you've got a clutch switch that won't let you start the truck until the clutch is ALL the way to the floor. You have to be sure to have the clutch pedal fully depressed or the truck won't try to start. Also, the clutch switch could be going bad, which could also cause this problem. I'm pretty sure '93s had this switch, as my dad's '94 does.

If it's an auto, maybe it's your shifter position interlock switch (the one that isn't supposed to let you start the truck in anything but Park or Neutral), that could be going bad and thinking you're in Reverse instead of Park.