I have a 1999 dodge Durango 4x4 with a 5.9 magnums v8. I've gone through 3 ignition coils in a 2 week span. Could it be just a bad "run" from the manufacturer? Or is there something I'm missing?
Hi Chris
I am not familiar with your particular vehicle. But...
The main reason that an ignition coil would fail is through an open circuit in the primary winding. (Use the ohms section of a multimeter to check for continuity) Now, the only way you can open circuit the primary winding is to burn out the primary winding.
Considering that this connects to 12 volts via the "points" or "contacts". There isn't much to go wrong.
So.... Here's what I think is happening.
From my old auto electrics background.... A coil connects to the vehicles 12 ignition circuit via a special nichrome wire (often inside the wiring harness) This Nichrome wire acts as a Resistor before the 12v current reaches the Coil's Primary winding. This cuts down the current when the the ignition key is in the running mode. When you start the vehicle, the full 12v current bypasses the resistor to give to a BOOST while starting the vehicle. When the key returns to the Running position the coil is being supplied by the resistance wire so the current is reduced.
Note: There would have been 2 wires connected to the Coil originally. One is 12v from ignition switch "run" position and one from ignition switch "start" position.
If you have wired the vehicle different than the original wiring or have used a different wire then you may actually be running the vehicle directly on 12v from the ignition/battery. This would eventually burn out your coil.
If necessary, add a resistor (large wire wound, ceramic), to the circuit. Purchase or make your own.... once you know how many ohms you require to reduce the current.
Hope this solves your problem. Pitty you have paid for 3 coils before finding out.
Cheers
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