Replaced starter, now cranking without key

Maintenance/Repairs
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1

Bought a new truck about a month ago, have had my old ranger parked since then. Went to start it up a few days ago and had power but no crank. Got the battery checked and it was bad so replaced it, didn’t fix the issue.

I just replaced the starter, but when I went to reconnect the battery, it immediately started to try to turn over on its own, without the key in the ignition. Not sure if this is a wiring issue or what. I have the signal wire on the 10mm stud and main power on the 13mm and I’m fairly sure that’s right but never swapped a starter before

2

Try removing the starter relay and then see if it cranks on its own.

Tester

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3

Not sure how your Ranger is configured but my Ford truck the starter only has one input. When it is +12 volts, it cranks the engine. The + 12 volts comes from the starter relay, which is bolted onto the fender as I recall. The starter relay is only supposed to energize the starter when the “start” terminal is +12 volts, which only occurs w/the key in “start”. [ Maybe it is labeled “ign” rather than “start”] I think what I’d do in this situation is remove the wire at the starter relay that goes to the starter motor. Then use a test light or DVM to determine if that terminals voltage is when the key is in “off” , “on”, and “start”. It should be zero volts in the first tow, and 12 volts in the last. The starter motor won’t crank in any of them b/c you disconnected the wire for the test.

BTW, I’ve had trouble with the starter relay before. One time it was just plain broken and needed replacement. Another time it had come loose from its moorings. It turns out the mounting fasteners also provide its ground. If it isn’t mounted soundly, it won’t work.

By contrast, the starter motor on my Corolla has two inputs. One directly from the battery, which is always 12 volts. The other comes from the ignition switch, and is only 12 volts when the key is in the “start” position.

4

I doubt if aregister really cares about your old vehicles George.

5

OP can post here if my info was of any value.

6

And that’s the way Ford starters have been for 20+ years.

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7

George was only pointing out 2 types of wiring setups for starters. Probably a bad relay, but it could be a weak Ignition switch spring. Next time you try it, turn the ignition switch to the left to make sure it retracts form the start position to the run position.