why my motor will not turn off from the key

Asked by Nov 23, 2012 at 11:30 PM

Question type: Maintenance & Repair

i replsce the ignition switch and tumbler

4 Answers

33,985

If it shuts off within a few minutes after the key is removed I would lean towards coolant leak. Due to the diesels high compression ratio and combustion temp the leaking coolant turns the engine into a steam engine. Check yohr coolant level.Google runaway diesel engine scary stuff. That's just a possibility though.

3 of 3 people found this helpful.

I am not disagreeing with John, his answer is good. I just have another possibility. The diesel engine has no ignition system, when you shut off the key what happens it sends a signal that shuts off fuel to injectors, killing the engine. The relay to the shut off may be bad. Cummings? Detroit Diesel? Cat? what?

5 of 5 people found this helpful.

If truck is equipped with a Qualcom or aftermarket radio check the wiring harness. I found a short between the Battery and Ignition wires. Once I repaired the chafed wires all is good.

A bad fues pannel its back feeding power to the ing fuse

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