Today: Help for Jeep Ignition Switch?

Dear Car Talk

Dear Car Talk | Jan 28, 2014

Dear Tom and Ray:

I have a 1979 Jeep CJ-7 with a 5-liter V-8 engine. The ignition switch is the type commonly used in vehicles of this vintage, and it's located on the steering column. It has an "accessory-only" position; an ignition-on, "run" position; and a spring-loaded, "crank" position, which activates the starter motor as long as you hold the key there. When I go to start the engine, I turn the ignition switch to the "crank" position, and the starter motor cranks normally. But the engine will not start until after I release the key and it springs back to the ignition-on, "run" position. I wired a remote starter switch directly into the starter solenoid and tried starting the car with that. And as long as the ignition switch was in the "run" position, I could make the starter motor crank and the engine fire up normally while the starter motor was still turning. Any ideas?

-- Michael

RAY: We were just trying to remember the last time we saw a '79 CJ-7 in the shop, Michael.

TOM: We couldn't remember, so we also took a moment to thank the automotive deities for that small blessing.

RAY: The first thing I'd suspect and test would be a bad ignition switch in the steering column.

TOM: What you want to do is test that "crank" position. When the key is in the crank position, both the starter motor and the coil are supposed to get power.

RAY: The starter motor, obviously, gets power to crank the engine and get it turning. And the coil gets power to fire the spark plugs, so that once the engine starts turning, it will "catch" and keep running on its own. You're obviously getting juice to the starter motor in the "crank" position, but maybe not to the coil.

TOM: You can find out with a test light. You obviously have some basic skills, since you hooked up a remote starter without setting your car on fire ... yet. So hook up the light between the negative terminal of the battery and the positive (ignition) side of the coil. Then turn the key to "crank." My guess is that nothing will light up.

RAY: That suggests that the ignition switch is bad. So your next step would be to try a new switch. But, as you know and undoubtedly toss and turn at night thinking about, changing the ignition switch in the CJ-7 is a pain the rear differential.

TOM: So try a new switch without installing it first. You should be able to reach under the steering column, unplug the wires that go into the existing switch and then plug those wires into your new switch, which you'll leave dangling from the wires for now.

RAY: Then use a screwdriver to turn the new switch and see what happens. If it works, you can then remove the steering wheel and all that, and install the new switch permanently.

TOM: Or just leave it dangling. I think that's a nice touch on a '79 CJ. Good luck, Michael.

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