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Post Info TOPIC: Common Chrysler PCM failures

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Status: Offline
Posts: 128
Date: Apr 6, 2015
Common Chrysler PCM failures

NO-Crank, NO Scan Tool Communication Complaints:

Sorry, to note that Chrysler PCM's have a high failure rate, and one of the more common complaints results in a NO-Crank with NO scan tool communication. Beware, because its NOT specifically a NO-Crank fault, its probably a "DEAD PCM" fault because the symptoms may only show up during cold start cranking. This usually occurs on SBEC, JTEC, and NGC type PCM's.

Bad Replacement PCM's:

OEM and aftermarket NEW and remanufactured Chrysler PCM's have a high failure rate right out of the box. Usually, after you replace a PCM and the same problem still exist you may have misdiagnosed the original fault. BUT, for JTEC PCM's it more common that the replacement PCM is suspected as defective.

Known HOT failures:

Many Chrysler PCM's can fail HOT, especially SBEC and JTEC PCM's. Try using a heat gun to duplicate the problems, and then try putting the PCM in the freezer for about 30 minutes to see if it will work again. The PCM will often work great for about 5-10 minutes after freezing.

Transistor Driver Faults:

Chrysler PCM's have alot of driver failure issues. This can cause actuators to stop working, with the ignition coil circuits becoming the most common problem. It is often possible that the PCM may intermittently hold an actuator control circuit to ground for too long. You will have to monitor the driver circuit waveform signals on a Lab Scope for quite a while to find these types of faults. For these pesky intermittent faults just try lightly tapping on the PCM casing to see if you can duplicate the problem.

Helpful NOTE:

Sometimes the PCM drivers stop working because the PCM shuts down completely. SO if you can connect the scan tool and it shows loss of communication, your fault is more likely the ASD relay, Relay control, or other PCM ground problems. Another clue to this is that the PCM will never run the Monitors and the fault keeps resetting the PCM memory as well. 

So keep in mind, certain PCM failures can cause a complete shut-down and reset as well but good chance the problem can be the ASD relay and PCM power and grounds. 





Status: Offline
Posts: 7
Date: Jan 26, 2016

Thanks for the post that's good info to know. I wont see them failing hot to often because its cold here in Chicago most of the year. lol

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