Crank No Start (with both coils plugged in)

MCobra25

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Bone stock 1996 4v Cobra was sitting for about 8 months came back to it to get it back on the road. It was parked running but sat so i wasnt getting fuel replaced the filter and the FPR because there wasnt any pressure after replacing the filter and now the fuel issues are all sorted. Problem now is the car will only start if i completely unplug the three wire connector going to the passenger side coil brick. When i unplug it the car starts and idles (on 4 cylinders) once i plug that side back in it dies. I swapped the two coils around to see if the problem was the coil itself and the issues stayed on the passenger side. I traced the signal wire (dark blue with light green tracer) back to the PCM and i do have continuity. I also checked the center wire in the 3 wire plug at the coil for 12v key on and i have it there as well. My concern is that my PCM is the actual issue here and it somehow developed a short while sitting. Or maybe one of the times i went out there to start it something happened who knows. Coming here to basically ask if you think that sounds right and making sure before i unload $200 for a PCM. To me seems pretty straight forward that theres a short within the PCM itself but ive been wrong before so i'll check whatever yous tell me just to be 100 percent certain. Thanks
 

lwarrior1016

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If you swap coils from one side to the other, then unplug the driver side coil will the car still run?
 
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MCobra25

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If you swap coils from one side to the other, then unplug the driver side coil will the car still run?
I did try that and no only when the passenger side three wire plug is unplug from whichever coil is there it runs. If i unplug the driver and leave the passenger plugged in it will not start.
 

lwarrior1016

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I did try that and no only when the passenger side three wire plug is unplug from whichever coil is there it runs. If i unplug the driver and leave the passenger plugged in it will not start.
Well that’s definitely odd. It kind of sounds like something is shorting in that circuit. You’ve checked the two signal wires all the way back to the computer and have a good circuit?
 

fairgreet

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Bone stock 1996 4v Cobra was sitting for about 8 months came back to it to get it back on the road. It was parked running but sat so i wasnt getting fuel replaced the filter and the FPR because there wasnt any pressure after replacing the filter and now the fuel issues are all sorted. Problem now is the car will only start if i completely unplug the three wire connector going to the passenger side coil brick. When i unplug it the car starts and idles (on 4 cylinders) once i plug that side back in it dies. I swapped the two coils around to see if the problem was the coil itself and the issues stayed on the passenger side. I traced the signal wire (dark blue with light green tracer) back to the PCM and i do have continuity. I also checked the center wire in the 3 wire plug at the coil for 12v key on and i have it there as well. My concern is that my PCM is the actual issue here and it somehow developed a short while sitting. Or maybe one of the times i went out there to start it something happened who knows. Coming here to basically ask if you think that sounds right and making sure before i unload $200 for a PCM. To me seems pretty straight forward that theres a short within the PCM itself but ive been wrong before so i'll check whatever yous tell me just to be 100 percent certain. Thanks
Hello there,

It sounds like you've done a thorough job diagnosing the issue with your 1996 4v Cobra. Based on your description, it does seem like the problem could be related to the PCM (Powertrain Control Module). Since you've checked the signal wire continuity and confirmed 12v at the key-on position, it suggests that the issue might be within the PCM or its connections.
 

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