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Jerry, Master Mechanic
Category: Dodge
Satisfied Customers: 1754
Experience:  ASE Master tech, 30 years exp. troubleshooter, driveability tech
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1991 Plymouth Voyager 3.6 liter. Encountering the following

Customer Question

1991 Plymouth Voyager 3.6 liter. Encountering the following problems:
Cranks but no spark, will not start. No power to coil pack. Crank and cam sensor are ok, relays are good. Possible/likely cause of this?
Submitted: 1 year ago.
Category: Dodge
Expert:  Dodgerench replied 1 year ago.

Hi, welcome to JustAnswer!. This is Ed.

If your cam and crank sensors truly are good, I'd be interested to know if your PCM (engine controller) is waking up. It could be a wiring problem or even failure of the PCM itself and a I have a few checks for you to make.

First, does the CHECK ENGINE lamp come on at key-on?

A CE light illumination is one of the first things a PCM commands as it wakes up with the key and is used as a "bulb check" function. If you see the CE light come on... pause 2-3 seconds... then go out, it means the PCM is at least waking up. No light? Maybe the bulb is burned out or maybe the PCM isn't able to fire it.

A second thing to check at key-on is for fuel pump/ Autoshutdown Relay operation. You should get a 1-second firing of the relay at key-on (both functions may be shared by one relay in this year). If you hear the fuel pump run, take a test light under the hood and check for power at the same time on the dark green/ black wire that goes to your coil pack. I'm assuming your engine is actually a 3.8 or 3.3 liter size in this model year.

If you had none of the functions I mentioned above come about at key-on, I think it's safe to say that your PCM might not be awake, but it can be for several reasons other than internal failure of the controller. Let me know what you find and whether you want to drag out the digital multimeter and 12v test light for diagnosis and we'll talk in a bit.