Logic module change

LAURAKEI

MEMBER
1987 CHRYSLER LE BARON
2.5L
4 CYL
2WD
AUTOMATIC
300,000 MILES

Hello!

Looked like my car listed above did not charge battery, so I brought alternator to restauration and they say it's in good condition, I have to look for voltage regulator. As I did not find it as a separate part, I tried changing the logic module. Disconnected both wires from battery and changed it. Afterwards the car does not start anymore. Turns but no spark. With either logic module, I tried putting the first one back. Any idea what might be the problem?

Hoping for some advice,
Laura

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

If we have no spark, then the common cause of this is a power module issue.

However, I am not sure replacing the alternator would have caused this. That does not change the fact that this is where we need to start with testing.

I am attaching the wiring diagrams below, so we need to check for power coming from the power module and going to the logic module.

https://www.2carpros.com/articles/how-to-check-wiring

Also, if you look at the diagram with the coil, we need to find out if the coil has 12 volts on the positive side and then if the power module is grounding that coil which is what interrupts the signal to create the high voltage spark.

If not, then the power module needs to be replaced.

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