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

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?

 

Is this a right hand drive vehicle?


Glenn Beasley
Chrysler Tech

 

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?

 

--

If there was a cable that made it easy to shut down the system, the alarm
would be worthless.
Take it to the dealer and have them scan the module, it will show up on the
scan tool what the last reason why the alarm was triggered.

Glenn Beasley
Chrysler Tech

 

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.

 

Sounds like a Microsoft style repair.

 

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.

 

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....

 

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.

 

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.

 

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

 

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.