Ignition coil over heats

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Welcome to JustAnswer. Thank you for contacting us for assistance with your vehicle. I'm Pete. I will be happy to assist you with your question. May I ask to whom I have the pleasure of speaking with today?

sonny

Hello Sonny. Nice to hear from you today! I'm sorry to hear you are having this problem. I know this can be frustrating. Is the ignition coil physically becoming hot to the touch or hot to where it stops operating?

gets hot to be very uncomfortable and the motor dies

Have you checked to make sure the wiring is tight at the coil and that it is secured properly with the ground cable at the back of it?

never seen a ground cable on when i took the old off

Thank you for your reply and that information as this does help me better understand the situation. Please give me one moment to type out some info for you. I’ll be right back! Thank you for holding Sonny! I had to re-check the ground information. Your model does not use an external ground as some do. Since the coil was replaced as well as the coil wire and spark plugs and other ignition components we can rule those out as a cause. In most cases, it is a fault with the cap and rotor or spark plug wires and spark plugs that creates high resistance which will cause this issue with the coil heating up and cutting off the engine. These have all been replaced. The only other reason the coil will heat up and cause the engine to shut down is if there is a wiring issue leading from the coil to the ignition system amplifier/module or a wiring fault leading from the coil to fuse 3. Loose wiring terminal connections or poor connections at the coil will also cause this issue. The loose connection or wiring issue causes high resistance which causes the coil to heat up and that will cause this problem. I recommend inspecting and trace the wiring leading from the coil to the ignition module for any issues as well as to fuse 3. Check to make sure fuse 3 is tight. If any issues are found with the wiring or the fuse then the affected wiring will need to be replaced or repaired. If fuse 3 is found to be loose in the fuse holder then the terminals in the fuse holder will need to be replaced or the fuse panel itself replaced to gain a better connection to the fuse.

Have I answered your question? If any part of my response is unclear, please let me know. It’s my goal to deliver excellent service, so please let me know if there is anything more I can do.

i ran a wire from the positive side of the [battery](/topics-battery-saab/) to the coil and it still over heated . then i put an inline resister and it over heated

O.k., we can rule out the power wire as the cause then. This leaves the wire or connection leading from the ignition module to the coil itself as an issue. This is the only other thing that would cause the coil to overheat and shut off the engine with all that you have performed and replaced on this vehicle.

i had the connection to the ignition module off and on a couple of times when i replaced it so it sounds like the wire itself

That is the most likely cause especially due to the age of the vehicle as wires tend to break down over time especially a wire that sends a signal like that. In most cases, I do find that it is the wire itself that has to be replaced completely.

any idea what color the wire is to the coil

I show it as a blue wire.

but when i run a wire from the battery it still over heats thats bypassing every thingby running a wire from the battery it does not have the reducer system (reduces voltage after it starts)

On this model, you have straight power from the fuse to a splice that splices to the ignition module and then the coil. No reducer is in line. The other wire ( blue ) runs directly from the module to the coil with no reducer in line. Below in the links is diagram information to help understand how it is wired up. [https://www.dropbox.com/s/j05ukxd1z88wq6m/co-02-25r.pdf?dl=0](https://www.dropbox.com/s/j05ukxd1z88wq6m/co-02-25r.pdf?dl=0) [https://www.dropbox.com/s/p2s9kl07r70dn92/coi-02-25.pdf?dl=0](https://www.dropbox.com/s/p2s9kl07r70dn92/coi-02-25.pdf?dl=0) So if the wire is faulty leading from the module to the coil that will cause the over heat issue and the wire will need to be replaced.

thank you

Your welcome! Glad I could be of some help! I hope everything works out well for you! If there are any additional questions on this issue that should arise, please feel free to reply and ask! Thank you for choosing Just Answer for your questions. Have a great day!

actually i found out that my [alternator](/topics-alternator-saab/) is putting out 29 volts . possible cures ?

29 volts is way too much. I haven't seen one put that many volts out. That can be caused by a poor power cable leading from the alternator to the battery with the cable needing to be replaced or an issue with the replacement alternator that was installed to where it has to be replaced again.

can i test the alternator

The alternator can be removed and taken into a local parts store where they can put it on their machine to test it for you for free. This is the best way to identify that it has to be replaced. Over voltage like this is usually caused by a faulty alternator.