Wednesday, May 03, 2006

Tip #13: Testing 94 Chrysler computers with ignition code

Chrysler engines computer in 1994 models is used to fire the ignition coils which produces spark. Instead of the regular set up where the ignition module is located remotely in your distributor or under the ignition coil, the ignition module is located inside the engine computer. Assuming you have no spark and has a check engine light flashing in your dash, what do you do?

First, verify the check engine light by retrieving the code using the ignition key. If you have an ignition fault code like 43 which means ignition coil failure, try replacing the ignition coil first. Then confirm the code by resetting the computer and see if the engine will start. Assuming you get the code again and has no spark, we can assume the only 2 causes of this problem will be:

1.) Wiring connections between the computer and ignition coil.
2.) Faulty engine computer

We can eliminate the wiring problem above by running our own wires between the ignition coil and computer and supplying power to the ignition coil direct from the battery. This leaves the engine computer as the only other possible source of the problem if the code or no start persists. Therefore, if it does not start and still the code returns, we can safely say the engine computer is defective.

Shown below is an example of Chrysler engine computer.

Remember to disconnect the battery before removing the computer.


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