Chrysler Repair: Sentry Key system periodically malfunctioning, computer circuitry, couple of times a year

Question
Roland,

For the past 8 years, a couple of times a year, I've had a recurring problem on my 2000 Sebring Convertible where the Sentry SKIM system does not recognize the key and shuts the car off a couple of seconds after starting.  The owner's manual says if the key isn't recognized, the red anti-theft light in the dashboard should flash continuously, but the light stays off.  Removing adjacent keys or other metal object and locking/unlocking the doors has never been a factor.

Usually, I can get past the problem by unplugging the battery and then plugging it back in, so it could be some static charge on the computer circuitry or clearing out some invalid state.  Since the battery is quite hard to get to in front of the wheel well, and I usually didn't have the tools with me, a few times I've been able to get it going by just pulling out some fuses in the box under the hood and putting them back in.  I think it may have been the ignition ones, but was never sure since I'd just pull a bunch of them and put them back.  Only one time did none of this work and I had to tow to one shop and then again to the dealer to get the computer reprogrammed with a new key.  Since then it happened again with the battery unplug being required.

It has only happened on hot afternoons (90 degrees plus in Texas summer), which makes sense that it would cause circuit problems but also makes the inconvenience factor much higher!  At least a couple of the times it coincided with a weak battery that was ready to be replaced, but it seems odd to me that there would be enough juice to start the car normally but then not enough to have the computer properly function.

Thanks so much for your service on this website!

Answer
Hi John,
The '00 manual has an 8-page section on the security system and security key system which mentions how to trouble shoot the module for power and ground. I can xerox and postal mail you that information. Another easier way to disconnect the battery is to look on one of the strut towers for the "remote ground connection of the battery and remove that. Unfortunately more complex problems with the system require diagnosis with the Chrysler Diagnostic Readout Box III which would have to be dealer-done. I can't give you a magic fix, unfortunately. But maybe having the pages that describe the system and some simple troubleshooting will prove helpful.
Roland