J10 cranks in run position.

[gridmark7]

I've recently purchased a 1977 Jeep J10 (originally a 401 quadratrac) that one of the previous owners had parted out. My goal at the moment is to get it back on the road so we borrowed the engine, trans, transfer case, and engine wiring harness from a 79 wagoneer.

Its mostly back together now but the starter cranks when the ignition switch is in the run position. I've tried disconnecting the alternator and the ignition module and nothing seems to change, I've also tried swapping the ignition switch with another I had on hand.

Also worth mentioning the wiring in this truck isn't in the best shape.

Here's the truck when we got it.

^that's the good side.


And here's the truck now.



Any ideas are appreciated I've got other harnesses if need be this one was just plug and play.(so I thought anyway)

Edit: I meant to put this in Stock FSJ Tech, oops.

[Stuka]

The ignition switch is at the bottom of the column. Its either internally worn out and you just need to replace it, or its actually in start when the key is in run.

[gridmark7]

I've tried 3 different switches (all of them used from other tilt columns) all have the same problem even after removing it from the column and moving the sliding piece by hand with a small hook tool. The column was just out of the truck for new bearings, turn signal switch, cruise/turn signal stalk. I got a new rack and sector gear for the key switch but neglected to change them as they seemed fine.

The switch that was originally on the column was sticky the other 2 feel good.
Local auto parts store never has anything and the next closest one is 150 miles away. Is there a way I can test the switches before I'm forced to order a new one?

[Stuka]

Ok, if they all act the same, even when pulled out, its most likely not the switch. The chances of having 3 bad ones in a row is pretty small, though not impossible.

In which case, it sounds like maybe your solenoid is wired wrong, or maybe your neutral safety switch is not hooked up.

[gridmark7]

Already checked the solenoid its also new. Neutral safety is something I haven't checked, that's the thing at the base of the column below the ignition switch correct? Its hooked up but I have no idea if its any good.

Edit: poked a test light around down there its only got power when the key is in the start position. And the start wire from the ignition switch to S on the solenoid has power in both Run and Start positions.

[will e]

1. Disconnect the small wires from the S and I terminals.
2. Turn the ignition to the ON position. Test the wire that was connected to the I terminal (the one closest to the starter side of the solenoid. It should have power.
3. Test the wire that was connected to the S side of the solenoid. It should NOT have power with the ignition in the ON position.

It's possible these two wires have been swapped. If they are swapped the engine will crank when the ignition is in the ON position.

The "I" wire goes to the positive terminal on the coil. This is energized by the solenoid during cranking to provide move voltage to the coil. While cranking the voltage drops significantly and the primary wire to your coil is a resistor wire that drops the voltage. When the engine is running the resistor wire is energized by the ignition switch to provide power to the coil. The 'I' wire also provides a path during cranking but the power will choose the least path of resistance which is through the solenoid to the coil. Since the 'I' wire is connected to the same spot on the coil as the ignition wire it is energized when the ignition is in the ON position. No electricity passes from the coil and through the 'I' wire in normal running operation because the 'I' terminal does not complete an electrical circuit when the solenoid is not activated.

[gridmark7]

Well, that did it. After flipping those around a few times previously I was convinced I had it right, but I was wrong. Thanks for making me check it again, its working like it should now.

Thanks again, Next hurdle is getting all the vacuum stuff hooked up.

[will e]

Cool! Sometimes it's the simple solutions.