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EricFromCT, ASE Certified Technician
Category: Car
Satisfied Customers: 3947
Experience:  ASE Master certified L1, L2, Diesel Certified 16 years experience
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Mitsubishi Galant ES: Ok this is really a dumb thing my buddy

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Ok this is really a dumb thing my buddy did! We were hooking up a shift tach. He was wanting to find the ground on the coil. So he put the test light on the positive side of the battery and probed the wires. When he hit one of the wires we lost both of those cylinders. The coil pack stopped working. It actually gets real hot when the car is running. WE REPLACED THE COIL PACK. Still gets hot and runs on 2 cylinders. I am asumming it probably shorted out the PCM?? Please help. Thanks.
Hi. If your buddy sent power to the pcm ground on pin 3 of either one of the coils then the pcm is probably shorted. That would either have been the W-G wire on coil 2 or the B-L wire on coil one. That pin is the pcm driver for the ground of that coil. Thanks, Eric
Customer: replied 4 years ago.

It was the black and blue wire on coil 2. Which is the one on the right if you looking at the front of engine. Yes it was the 3 pin from the power wire . We put a new coil on still the same. The other thing I noticed was the coil was so hot you could not touch it after running on 2 cylinders in about 3 min. What should the voltage be at the signal wire? The left coil read .093. The coil that is not firing was reading 6.9v at the signal wire? I think the ecm is bad now?

Yeah the ecm is bad. The ecm cycles the ground for the coil on pin 3 for each coil. Each coil has its own ground that the ecm duty cycles to work the coil. There should not be 6.9 volts. There should be 0 volts as it is a ground circuit The transistor in the ecm is bad now and is causing the coil to stay powered constantly. Thats why it is heating up like that. The ecm is bad.
Thank you for using Just Answer. Please remember to rate the service that I provided in regards XXXXX XXXXX Mitsubishi. Thanks again! Eric
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