New starter solenoid, now vehicle starts without key in ignition

BLACKFOOT501

MEMBER
1975 JEEP CJ5
4.2L
6 CYL
4WD
MANUAL
300,000 MILES

My vehicle listed above had power to lights and dash cluster, but would not start. Checked battery and has plenty of juice. Would just click. Replaced starter solenoid, as soon as positive side of battery was connected the vehicle kept trying to start on its own without a key in the ignition. This is my first vehicle and I am far from a mechanic.

Monday, March 29th, 2021 AT 9:58 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Sounds like the solenoid is getting constant power on the control wire. This is most likely due to the solenoid being shorted internally. If it were me, I would return that solenoid and have them provide another.

Basically the way this works is when you supply one side of the solenoid with battery voltage and then the trigger wire is supplied 12 volts with the ignition switch, the solenoid supplies battery voltage to the starter. So if it is getting that voltage all the time then it is shorted.

The only other thing is to make sure you have the wires connected properly. Here is a video showing how to do this on another solenoid. If you have voltage going straight to the starter side of the solenoid then it will have power all the time.

https://youtu.be/Y56wVWLvhvU

Let me know if you have questions on this. Thanks

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Wednesday, March 31st, 2021 AT 2:45 PM