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Chrysler PCM horror stories and simple solution
Posted to Technical Tips Forum on 1/14/2011 28 Replies

Over the years I have read enough horror stories about Chrysler PCM (old style no CAN vehicles). Like swapping it from another car for testing purposes and now the donor has not start condition. It happened because of VTSS system. This system is optional and could be turned on by DRBIII but could not turn off once enabled. Option is sitting in a body computer and it could be evoke only from there. There is not such option in PCM. It will acquire this option once and forever the second it sees VTSS message on communication network (CCD or PCI bus). So the only way to make such PCM working on non-VTSS vehicle is to make it on in body computer. Sometime it is not even possible because Chrysler has low tech BCMs without this option. More often a hardware (like door switches) not installed on particular vehicle. So you can turn it on but in case this system goes off owner will have a hard time to disarm it and start the car. VTSS system has nothing to do with SKIM or SKREEM and not VIN related, so any PCM from VTSS vehicle will start another VTSS vehicle without any additional procedures if SKIM module not installed.

There is a way to remove VTSS system form PCM though I bet not many people know how it can be done. In case you did such stupid experiment swapping PCMs between two cars and now have donor with no start you should do following.

Plug PCM from donor back to the car which has VTSS option in body computer on. Turn ignition ON.

With ignition ON short two CCD wires together or PCI line to the ground. This will effectively kill communication between modules.

Shut ignition OFF, disconnect PCM and plug it back to the vehicle it belongs. Donor car should start right away.

You can do your own research to prove I not making this up. Let say you have vehicle in your shop which has VTSS on. Let say it has PCI bus. Try to short communication line to ground (with ignition off) and start the engine. It will be not possible because PCM not getting VTSS message from BCM. OK, next step -- remove short from line and turn ignition on. With ignition on short communication line again. And now watch what a surprise, car will start with line shorted every time. Learned VTSS system is permanently removed from PCM configuration.


Vladimir from New York

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