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Dr. Hamman
Dr. Hamman, Ford Technician
Category: Ford
Satisfied Customers: 6286
Experience:  I have 30 years of Ford Technician experience. I have built many custom Fords, I also collect them.
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F 150: 1987 f150- i crossed the cables on battery. It will

Customer Question

1987 f150- i crossed the cables on battery. It will crank but win't start. Changed solenoid. Tested alternator changed alt harness, map sensor, ignition coil, dist cap, changed battery cables-both. Still same problem
Submitted: 2 years ago.
Category: Ford
Expert:  Dr. Hamman replied 2 years ago.
Hi, I am a professional certified mechanic, with an engineering background,and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice, so feel free to add any additional info at any time. I am an electrical specialist and I will try to help you out with this problem. What the reverse polarity hurts is electronic circuit boards, normal electrical parts usually survive. Diodes in particular on the circuit boards, they short out, and it kills the function of the boards. Typically you will loose the radio if it was on, and other electronics like the engines computer, and the ignition module can be toast. It is easy to check the ignitions spark to determine if the module is bad. The engine computer takes special tools to test.The computer is located behind the drivers side kick panel, and the electrical connector bolts on from the engine compartment. There are no absolutes as far as what to do, odds are you lost the engine computer, the radio and the ignition module probably survived if the ignition was off. Go over all of this and if you have any more questions at all, I am here to help.Good luck with it, have a great day, and Thanks for using Just Answer.I do not get paid for my work unless you rate at 3 to 5 Smiley Faces or Stars, a bonus is always greatly appreciated. If the answer is not clear, let me know what additional help you need, and I will be happy to assist you further.