Intermittently will not turn off with the ignition switch

1989 ISUZU TROOPER
160,000 MILES • V6 • 4WD • MANUAL
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HEREBITTY
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  • 4 POSTS
The engine will not shutoff with the switch. intermittent. have to pull ignition fuse. I changed the ignition switch, but it did not help.
Dec 24, 2021 at 1:35 PM
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AL514
  • ASE Certified Mechanic
  • 5,587 POSTS
  • ASE Certified Mechanic
Hello, because of the vehicles age, it's very difficult to find the correct wiring diagrams. Is it Fuse #14 you have to pull? It sounds like you have a relay that has some carbon build up on the contacts and is keeping a circuit to the ECM active. Can you pull the Main Relay here in the diagram below and see if it will stop the engine? Also, when the issue does happen before you pull any fuses or do anything else. You should see which pin on the ECM is still receiving 12volts. If it's (in green) this ECM Pin A6 black/white wire, then you would know it's this main relay keeping its contacts active. Again, we have very limited wiring diagrams, so any fuse number that you're pulling, or additional info would help. But a relay staying on is really the only thing I can see to keep the engine running. Unless there's a circuit inside the ECM that has a corroded and causing contact. But checking any connectors for corrosion would help too.
Is this problem running the battery down overnight as well?


https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-to-check-wiring
Dec 24, 2021 at 5:51 PM
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HEREBITTY
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Thanks, clicking relay. also, the connection from key module to switch to see if any play in connector will advise.
Dec 28, 2021 at 10:01 AM
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HEREBITTY
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pulled out a new ignition switch and used a flat screwdriver to turn the switch. The engine cranked okay, but the same problem as engine did not shut off. Pulled ignition fuse to shut off engine.
Dec 30, 2021 at 7:16 AM
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HEREBITTY
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pulled main relay, engine stopped.
Dec 30, 2021 at 9:01 AM
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AL514
  • ASE Certified Mechanic
  • 5,587 POSTS
  • ASE Certified Mechanic
If you have the vehicle running and can't shut it off, you can check for power at these two locations with a test light (in yellow), that will tell you the relays still powered up. The other control wire for the relay that says "Hot in Run or Start" should not have power when the ignition switch is off. Is there a number for the Ignition Fuse?

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
Dec 30, 2021 at 10:59 AM
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