The chime is built into the instrument cluster which is actually a very sophisticated computer module, and gets some of its information from the central timer module which is the body computer, and can not be disabled. The body computer provides the voltages on the two data buss wires that all the vehicle's computers use to talk back and forth to each other. Kinda makes you long for the old days when every imaginable thing on a vehicle didn't need a computer to work. I have a head light chime on my '88 Grand Caravan, but no need for the unreliable, complicated computers.
First of all, do your dome lights work properly? If the bulbs are burned out, they may be receiving power at the same time your chime is sounding. Then, the problem could be as simple as a door switch out of adjustment. Open each door, one at a time, and push in the dome light switch. On older cars and trucks, multiple contacts served each circuit. The headlight chime and dome lights were on different wires. We don't want to overlook something simple, but I believe your switches only have one wire that goes to the body computer which sorts everything out. In other words, if the switch was out of adjustment, the dome lights should be on too.
If the dome lights are working properly, the door switches are too. In that case, the problem is in the central timer module. It is what sends the signal to the instrument cluster to turn on the chime.
There may be a solution besides replacing the module. A '99 service manual is the newest I have, but I think the circuitry is the same. There is a wire from the headlight switch that goes to the module to tell it when the headlights are on. In my book, there are two wires. Cutting either one of them will mimic a switch that is turned off. One is light blue and the other is black with a light blue stripe. Both are 20 gauge which is really small.
I'm having a hard time understanding the circuit. There is a second switch for the ignition key. That's in the same circuit, but I'm guessing it turns off when the switch is in the "Run" position. By cutting a wire on the headlight switch, the chime will still warn you if you leave the key in the cylinder when you open a door. If I'm right about how this circuit works, I think you will find that the chime turns on also when the key is in the cylinder in the off or lock position, and the doors are still closed. If it does and you want to disable that too, you will need to find the light blue wire at the central timer module and cut it there.
If you have the means to diagnose this circuit properly, measure the voltage on that light blue wire. It's pin 9 in connector 1 in my book. The voltage should go to 0 volts when the driver's door is opened, AND when either the headlights are on or the key is in the ignition switch, (in "Run"). If it is also near 0 volts when the door is closed, there must be a problem with the central timer module. A grounded wire is not a possibility because the dome lights would be on too. Only a different pin in the module that is in the same circuit could be causing the problem. That's pin 1 in connector 1, and is the same black wire with light blue stripe that goes to the headlight switch.
Sure was simpler when they didn't have all these computers.
Friday, December 11th, 2009 AT 4:46 AM