DanielRicany

Hi guys, I have a 1985 Corvette and for the longest time, the seat belt light hasn't been working. Well today I discovered that my Audio Alarm Module seems fried. Interestingly though, my two wires going to the seat buckle female end were cut by the previous owner. According to All Data, one wire has power, one wire has ground, and is normally closed, when you plug the seat belt in, it switches to open, and the light goes out.

I had 8.4 volts at the power wire using my power probe, but when I used my multimeter, it said 12 volts.

Okay, so I traced all the way back to the module, after hours of ripping apart the dashboard. I have voltage coming out of the one black wire at the module, and ground from the other black wire. I have power at the two power feeds. When I had the two black wires connected, there was ground at the yellow wire for the seat belt light, this wire should have power. Okay, so the module is not working properly.

I took it out and started looking online for a replacement. The ones that I see on google images are blue. Mine is white. Is it supposed to be blue? Because this leads me to think that something is causing these to fail, as maybe the previous owner had already replaced it. I'm just wondering if there was a short circuit or something?

When I had opened up the box of the module, there was a burn stain on the lid. I am going to bench test it soon, but I was just wondering about these things.

Also, where can I get a replacement? Thanks a lot!

DanielRicany

Okay actually a little bit of a change. I jumped the connector to the seat belt with a paper clip. The power line coming to the seat belt was only 8.4 volts, and the power going to the bulb itself was only 10.8 volts. So there is a problem with high resistance. Since I have everything that is required going into the module, the module is not working properly, so I am going to replace it. Any ideas on what usually would cause high resistance in this module?

DUB

I will have to look in my 1985 service manual but something from AllData seems to be incorrect.

It makes NO SENSE to have 12 volts and ground at the same point...because it would be a short at the seat belt clip....because they are not energizing anything at this point of contact....much like when power and ground are together to light up a light bulb.

It seems more logical that ground would go through the seat belt clip and when the buckle is inserted...it breaks(opens) the contacts of ground ...thus turning off the light due to it taking away the ground needed for making the light bulb work.

Like I wrote....logically I would NOT think that GM would have power going to an area where it can possibly ground out and cause a fire...especially a part that can move constantly.....but I have been wrong in the past...so this is why i need to look at the manual tomorrow and get back to you....unless someone else posted the wiring schematic.

As for the audio alarm. ....You can contact GARY or GARLAND at Vette Pros (704)249-0437 or (704)320-0073. I know they have rebuilt ones...I jut say them the other day....and I believe they are a medium/light blue case.

DUB

Cliff Harris

The chime module chimes when

- the driver's seat belt is not fastened when the ignition is turned on.
- the door is open with the key in the ignition, ignition off.
- the parking lights or headlights are turned on when the ignition is off.

If none of these things work then your module is probably bad. If at least one works then the problem is elsewhere. Both the CTSY/CLK fuse and the GAGES fuse must be OK for the chime module to work.

According to my parts book, that's an "ALARM, ST BELT, IGN KEY & LPS", with two part numbers (no mention of colors):

11062571 - 1984
10037040 - 1985 to 1989

AGENT 86

No power at seat belt. This info from my 86 service manual should help more than All Data's did.

http://members.shaw.ca/agent86/Chimes.pdf

DanielRicany

When I first started diagnosing it, I thought the same thing. But I didn't see anything about a resistor keeping the voltage at 5v in the solid state on the diagram, it is really confusing, because looking at the diagram, the seat belt ground wire doesn't go back to the computer for a ground, it just goes straight to ground. Not really sure how it works unless I would be able to see a diagram of the inside of the module.

They all work except for the seat belt light. Like I said before, I'm dealing with high resistance built up inside the module because of the following reasons. I have 8.4 volts at the seat belt hot wire, I have 10.8 volts at the light bulb hot wire, I have 12v at the two power feeds to the module, and I have a good ground to the module.

Thanks. All Data gave me the same wiring diagram, but not the description of the circuit, I will look over it.

AGENT 86

If it's the same, you should have seen that the seat belt switch allows a ground path to module, nothing more.

DanielRicany

Yes that is what it does. The module recognizes the ground and then sends power to the light bulb. But why would the module produce 12 volts to a direct ground and still not burn up a wire or blow a fuse?

Cliff Harris

Because the 12 volts goes through a resistor. When you measure a voltage "open circuit" (not connected to anything), there is no current flowing and therefore no voltage drop.

DanielRicany

I measured the resistance of the seat belt switch and it came out to 5 ohms. Also, I had moved the car today to get another car in the bay and notice the seat belt light came on with the same module in. I said what the hell? I wiggled the box around and the light wouldn't come on, wiggled it some more and it came on again. It turns out the pink wire with black tracer had a bad connection to the terminal on the module. The female connector was loose inside the main connector, so tomorrow I am going to order a set of connectors from the local parts store and replace it. I was able to hold the connector to the terminal and the light would come on, if I moved it away from the terminal it wouldn't come on. This would explain the strange voltage readings I was getting before.