Pontiac Bonneville Ignition Module Keeps Blowing

1993 Pontiac Bonneville 3.8L.
Repairs= The car has had the ignition module replaced and the crank sensor replaced. Question = Hi I was searching around and found your site and can tell you guys know what you're talking about. I have worked on cars at a dealer for 15 years and know a lot about most things, but you always get a basket case now and again.

This Bonneville keeps blowing the ignition module. It came to me and the owner said a shop had already replaced the ignition module and drove the car about 2 miles and it died. They then replaced the crank sensor and the car still wouldn't start. I got the car and checked the ignition module by doing tests for the 3x and 18x crank signal checked for power and ground at the module blah blah blah.

I put on a new ignition module the car ran great. The alternator was charging around 14.3 or 14.5 volts. I drove the car less than a mile the car died and needs another ignition module. The ground from the battery and everything is right below the module on the head and the ground wire to the module was good so I don't think it is a ground issue.

I am at a loss here and really think it must be an overcharging or voltage spike issue, but like I said it seemed to charge NORMAL voltage. The coils maybe? I'd like any help you could give. Please and thanks, Ben.

pontiac bonneville

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Talking to the guys we have never seen something like this. About the only thing we can think of to keep blowing an ignition module is a bad coil spiking the module. I have seen several times these 3800 ignition coils have a crack in one and under a heavy load will arc to ground through the module. That is very bad.

Try spraying a little water on the coil while doing a brake torque to see if spark jumps out of one of the coils. You would hear it and see it too. This will put a heavy load on the ignition system and cause any problems to show itself.

Make sure the ground is good. The module gets it's ground through the bottom of the module on the bracket. If there is corrosion between the module and bracket that will effect the ground resistance. Best to check ground continuity with a DVOM from the car chassis or engine to the negative battery terminal.

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