My Cherokee starts fine but as soon as I touch the brake pedal it kills the engine. If I keep my foot on the brake pedal it won't start. I tried disconnecting the wire to the brake light switch but if I do this it won't start. The brake lights work fine and the hazard lights work so I don't think the switch is the problem. Does anybody know what this problem is? Glen
Glen Hudgin did pass the time by typing:
Without a wiring schematic I can't give you more than suggestions.
First the basics: Do you have an aftermarket alarm system on your Jeep?
Go through and check every fuse.
Assuming you have an automatic transmission, try starting the Jeep in Neutral. (possibly the park safety/interlock switch) But that usually results in a no-start.
Something in the ignition circuit has lost its ground and is finding one through the brake lamp system. (actually if something is, the lamps should glow) When you press the brakes that puts 12v to the lamp and interferes with the engine operation. Try putting a jumpercable between the engine block and the frame. If that works then it's your engine ground strap that has rotted.
That should be a dead mesh ground strap from the rear of the engine head to the firewall.
There is a 99% chance your vehicle is stealing the ground through the brake pedal and light circuit.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT'sGlen Hudg>
I believe there was a recall on the shift interlock switch not sure why but you might want to check that you are up to date on recalls.
Also see if the bake pedal hits some wiring for the ECM. When you hit the Brakes, does the tach drop dead instantly like the power was cut off? If so then I agree with ("ßill")
Ok seeing as you have new ground straps, (everyone should know this), I would take a booster cable and run it from the battery negative to the firewall and see what happens.
If no change, I would then turn on the emergency flashers and see if a) it starts with them on or b) it dies when they come on or c) they have no effect.
There is one other place to check for a broken ground as well. Look on the passenger side of the engine near the back for a bolt with 2 or 3 small black wires coming off it. This is the ground for the computer harness.
Have you had any wiring issues or melts or bad electrical smells? Anything like the 4x4 light stuck on or anything else unusual?
Mike
Mike Roma>
Problem solved. It was a bad ground wire, apparently for the computer or control unit. Thanks for all the input.
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