Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

78 gmc 6000

replaced starter after which when i turn key to on position starter will engage and actually start engine; turn to accessory and starter will engage but wont start engine. checked double checked and so on installation.and then exchanged for another rebuilt starter with same results. the reason for replacing the starter in the first place was during the winter went out to start to let motor run fur a while which it did. went to move before completely warmed up and killed engine starter never made another sound. any suggestions?

A wiring diagram would be very helpful in diagnosing this problem. Without it you will spend a great deal of time and effort tracing wires. Even an experienced GMC mechanic over the age of 60 won’t be able to help unless he as seen the problem himself. That is unlikely. But the first place to check is the ignition switch.

thanks rod knox, that was kind of where i thought about starting my search. but being really dreadful of getting into wiring harness wondered if someone may have had this problem. but even if they had i know when it comes to electrical issues it’s a crap shoot at least for me.

Check the small terminals on the starter, the purple wire should be on the “S” terminal. The other wire should be on the other small terminal, marked R. The R terminal sends power to the coil while the starter is engauged.

ok, got that but there was no wire on the outside small terminal. there was the two wire on the center post and one on the inside small post. could that have something to do with my trouble. i’ve only owned truck for 10 months now but it always started and ran well before this.

If the starter motor is turning on when the ignition switch is to the the ON position rather than the START position the trouble is with the actual ignition switch. It has moved to the wrong position somehow.

i’ve taken the switch out and used a jumper wire to start and works fine like that so i’m going to replace and hope that is the cure. thanks

Many GMs do not use the “R” lug on the starter, and this is probably one of them. My best guess is an ignition switch problem.

i think i’ve narrowed it down to ignition switch. thanks for all comments

I’m not sure, but are you trying to start the truck in the “Accessory” position? That position doesn’t sound like that is supposed to active the engine electricals - just the accessories!