96 Blazer, 121k miles, Starting w/o Key

We recently purchased a used 1996 Blazer with 121k miles. Initially the brake lights would not operate. Troubleshooting identified a bad turn signal switch. It has since been replaced and the brake lights are working. The new problem, which began just prior to switch replacement, is the truck starts without having the key in the ignition. Battery has been disconnected and when re-connected, the truck turns over, runs for a few moments, and then stalls out. Any suggestions of where to start would be appreciated.

You need to take an ohm's meter, and check at your solenoid switch at the starter with the battery unhooked, check from the big wire that goes to the battery to the one that goes to the actual starter. If you are reading 0 ohm's something is wrong with your solenoid switch. If you aren't then something is feeding juice to the smaller wire going to your solenoid when you first hook the battery up. I would think something screwed up in the ignition switch. Unhook the big wire going to the solenoid, then hook your battery back up, then check with a test light or a volt meter to the small wire after hooking the battery up and it shouldn't show any voltage there until the key is in the start position.


Is this an intermittent problem?

Operation of the ignition appeard to be fine when the truck was driven home. The problem only began in conjunction with the diagnosis of the turn signal switch failure. I have to assume I did something while diagnosing the switch. I do have a schematic and can easily determine the correct wires to be tested, but I'm fairly certain it will turn out to be the smaller wire. I will run the test described and post the results when known.

Does the vehicle have an aftermarket security system, or remote starter? If so, you'll most likely find the problem there.

OM, you may be correct. Starter checked out fine. However, I did repair a broken wire in the aftermarket security system (Cobra system) in conjunction with the directional switch replacement. I plan to test the security circuit this afternoon. Will post final results.

OM, You are aptly named. I cut out the aftermarket security system, A Python System, taped off all exposed wires and the truck started as it should, with the key, and idled without any problems. I have a few more switches to troubleshoot, 4wd and passenger window switches, and then I'll work into the PM phase of the project. Oil, tranny fluid, etc. When completed, it should be a decent vehicle for anoth 100k miles. Thanks to all for the information.

Thanks for the kind words. Glad you got her fixed, and thanks for posting back the solution. Good luck with your "adventure". Feel free to start a new thread with any questions that you have on the other items.

OM, You are aptly named. I cut out the aftermarket security system, A Python System, taped off all exposed wires and the truck started as it should, with the key, and idled without any problems. I have a few more switches to troubleshoot, 4wd and passenger window switches, and then I'll work into the PM phase of the project. Oil, tranny fluid, etc. When completed, it should be a decent vehicle for anoth 100k miles. Thanks to all for the information.

Great Job, Thanks for posting back. I agree on the Kudos for Old Master.

I truly think he should change his name to:

The Greatest All Knowing Grand and Glorious Master that ever Twisted a wrench.

Rick, That's a bit extreme, but thank you. I can't take full credit... Someone that I admire and respect coined a phrase that really hits the nail on the head... "Talent on loan from God". ;)