Car alarm failure on the 300C (how do you disable the alarm)

Apr 23, 2006 11 Replies
G

The alarm on my 06 300C failed on me yesterday disabling the car. The alarm has gone of spontaneously a couple of times but it always recovered before. Yesterday it failed and I couldn't get it to reset so I had the car towed to the dealer.



The details of the failure are as follows. The car wouldn't respond to the keyless entry commands. When I opened the door with the key the alarm went off. Putting the key in the ignition wouldn't stop it and the car wouldn't start. To add insult to injury I couldn't get to the battery to disconnect it because the battery is in the trunk and the alarm system disabled the truck button on the dash and the keyless entry buttons weren't working (I tried both of my key rings so I don't think it's a problem with the batteries in the key rings).



This was the most embarrassing kind of failure, I was in the parking lot of an Audubon society bird sanctuary and they were having a lecture. You can imagine how popular I was.



There must be a battery cable that comes from the trunk to engine compartment, is there a place where this cable can be easily disconnected? Is there any sort of system reset button in the car?



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D

Is this a right hand drive vehicle?

Glenn Beasley Chrysler Tech

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G

No it's a regular American 300C.

The dealer said they spent four hours on it although all they did was a firmware update. Frankly I doubt that they've fixed the problem, if this were a software problem it would be happening to lot's of people. It feels like an electrical or hardware problem to me. Has anyone heard of an alarm lock up problem to the 300C? Does anyone know if it's possible to have the alarm disabled or devoiced?

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G

I got my car back from the dealer, all they did was reset the computer. Chrysler has had a few reports of similar failures but they haven't issued an ECO yet. For now the only solution is to reset the system when the computer locks up. For the benefit of others here is how you do it,

1) When the computer is locked up the normal methods of opening the trunk are disabled, i.e. the button on the dash and the keyless remote. However the back seat in the 300 folds down so it's possible to access the trunk from the back seat. Once the back seat is down you can reach in and pull the kidnap cable which opens the trunk. 2) The circuit breaker box is easily accessible, just lift up the carpet and its right there. The left hand circuit breaker (it's black) controls the power to the relevant computer (there are 30 computers in a 300, don't know if they are all on the same circuit). You pull up the circuit breaker and wait at least 10 minutes, then you reconnect the circuit and the system should operate normally.
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A

Sounds like a Microsoft style repair.

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G

It is a Microsoft style repair because it's a Microsoft type bug. The 300 has a BSOD problem. I suspect that it's really a hardware problem, probably undershoot on a sensor line or perhaps a power supply glitch. If it were purely a software problem then it would be much more common then it apparently is. However it could be an exception handling bug in the software, i.e some sensor or combination of sensors is giving a reading that the software doesn't handle correctly which causes the computer to crash.

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M

It's bad enough that the car is ugly looking. Now we learn that it's electronic systems were designed by Rube Goldberg.

Did anyone think of using the key to unlock the trunk from the outside? Or does the Tonka-300 not have a key-lock mechanism for the trunk?

Bill Gates would require a separate XP licence for each computer.

Dave, what are you doing Dave. I know I've been acting erratically lately....

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G

There is no key lock on the 300's trunk, the only way to open the trunk is with the keyless remote, the trunk button on the dash (which is electronic, it's not connected to a cable), or with the kidnap release which is there so mafia snitches can get out of the trunk before Tony has a chance to pop them.

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S

Its got a key- only GM and Toyota are aggressively eliminating key locks. The rental Impala I had as a rental not too long ago had NO trunk key slot, and NO passenger door key. Totally dependent on the little key fob to get in the trunk. Pretty soon they'll eliminate the driver's door key slot. GM and Toyota have also eliminated transmission dipsticks on many models. Yee-ha.

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S

I sit corrected- I hear that 300's DON'T have trunk key-locks. Thank God they still have real transmissions, at least.

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S

I'd locate the alarm horn wiring and insert a simple switch in the circuit for future use.

The lack of a key lock on the trunk was one of the many reasons I passed on the 300.. This is unacceptable design which I know comes from Europe, where I've seen it there on rental cars for some time. I once rented a Renault which had NO key locks anywhere. I assume there was some way to get in if the battery failed, but typical of rental cars the owners manual wasn't to be seen.

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