QuestionQUESTION: I have a 1999 Sebring convertible that has an issue with the factory alarm. When the door is opened, the horn honks, the headlights flash, the interior lights flash and the dashboard lights are off. There is also a red light on the dashboard that is lit. The car is able to be driven by turning on the lights and the horn has been disconnected under the hood. I ordered a new key fob but the locksmith was not able to program it to the car. Then I took it to the dealer and he said he could replace the BCM for $1,400 plus labor. The dealer had a kid working who didn't spend much time but they didn't charge me. This is a nice car but that expense is too much. I have done the unlock left-right-left thing and that doesn't work. It was suggested to disconnect the battery to reset the BCM, but haven't tried that yet because the car is driving. Any suggestions?
ANSWER: Hi Richard,
If the key has the bulge in its handle then you have two different anti-theft systems in the car. One is tied into the door locks the other is tied into the ignition switch. The fact that the engine will run suggests that the problem is NOT with the ignition switch systems because that would be where the engine would fail to run beyond a second or so if it was 'unhappy'. So I would not spend any time on the bulge key fob approach.
If indeed the issue is with the horn and the lights flashing then that presumably is confined to the door lock anti-theft system and the most likely reason is that both the wires from the front doors have fatigued at the hinge such that the signal sent from the locks are not getting to the BCM. There are a couple of harnesses at the hinge that could be examined to try and find the wire in question and having found that if 12v was jumped from a fuse in the fuse box at the left end cap of the dash to that specific wire it would then disarm the door system. (Another approach would be to go under the dash to the BCM plugs where the wires end up but that may be more of a hassle than what I will describe now).
From that point in time you can either repair the wire or simply prevent the system from ever arming again by only using the mechanical push buttons to secure the doors when you exit the vehicle. You would not use the power locks, the remote, or the door key to lock the vehicle. Only use the door key to unlock the vehicle. Or you could see if that wire in question indeed appears to be 'open' at that point and if so repair it.
The disarming wire on the driver side is light green/orange stripe. The two harnesses each have 12 wires and if you can spot the plug for the harness at the hinge it is brown in color (while the other harness plug is blue and not of interest to you). The wire in question is on pin 12 of the plug/socket if you can access that instead of probing into the harness.
Unfortunately the antitheft systems are not simply individually disconnectable from the overall circuit so you have to use the 'work around' I have described.
Please 'rate' my answer (see the PS below, today is the last day of February and I need your nomination to compete for 'volunteer of the month' here at Allexperts).
Thanks,
Roland
---------- FOLLOW-UP ----------
QUESTION: I am an Electrical Engineer and a solder jock so I will check out the continuity issue described. Another "new feature" is that when the key is used to unlock the car, the electric lock will try to lock the door again so you have to open the door before it locks again. This seems to be consistent with a door lock anti-theft system. I will get back to you with any results. Thanks!
AnswerHi Richard, Thanks for the follow-up and the rating/nomination.
Note that I revised my answer below, a bit.
Because you are getting some sort of a response where the lock sets again suggests to me rather that you may have a problem at the door lock switch itself. Both the door lock and unlock sense signal is carried on the same light green/orange wire to the bcm. So somehow there is a constant door "lock" signal being generated at the switch. That signal is a voltage that has passed through a 680 ohm resistor inside the lock before going back to the BCM, and the unlock signal is after 12v passes through a 2700 ohm resistor to the bcm. So that is going to require you to remove the door trim panel to get to the switch. Perhaps the best approach would be to see if the light green/orange wire shows a constant LESS than 12v on it which would corroborate my theory that it is either the door lock or short of the light green/orange wite to a less than 12v wire inside the door or on the way to the bcm (pin 19 of the black 20-pin plug of the bcm if you go looking for that which is on the back side of the fuse box and has 5 different plugs). I am pleased to know you are an electrical engineer!.
Roland
