73 rr. Seat belt light and buzzer troubles

[midnightrider1818]

hey guys. I have something weird going on with the seat belt light and buzzer. I got it to work but this is the only way I can get it to work. ok here goes. first off the light and buzzer will only work with the KEY OFF. I took a 12 v jumper wire and touched it to the top terminal of the relay and light and buzzer comes on. If you do this and turn the ignition on the light and buzzer will not come on. almost like it is losing ground with the ignition on. the seat belt systems are working just as it should. light and buzzer on pull driver side seat belt out and it goes off. clip drivers side and go sit on passenger side light and buzzer come on and pull seat belt out it goes off. So I know all that is working like it should. Ok with the key on I have 12v at the relay and a ground at the relay. I also have 12 v going to top terminal on relay. but light and buzzer will not come on. again if I turn the ignition off of course I lose my 12 v to the relay but if I take a jumper wire and put on top terminal light and buzzer WILL COME ON. If I turn the switch ON buzzer and light will go off. I have constant 12v battery voltage going to the top terminal on relay so yes it is hot whether key is on or of

this has really got me stumped. Again I think I am somehow losing a ground to the light and buzzer when key is on. does anybody have any information on this lol. It has got me stumped. thanks a lot guys really really appreciate everything. I would never be where I am now without you guys.

 

[idrivemopar]

Question, are you testing when the car is in gear? The buzzer and light should only come on when the ignition is on and car is in gear, and you are in the driver seat and seatbelt is not fastened. Same with passenger side if someone is sitting there, ignition on and car in gear, and seatbelt is not fastened.

 

[midnightrider1818]

No i am not testing while the car is in gear.

 

[midnightrider1818]

I didnt know the car had to be in gear. Where does it get that signal from letting it know its in gear.

 

[idrivemopar]

Yes, I believe the ground signal comes from the neutral safety switch on the transmission if its an automatic.

 

[midnightrider1818]

ok update. still no good whether car is in neutral or park. however I tore the glove box out and went to the buzzer. key on I have 12 v to buzzer but no ground. key off I have a ground to buzzer but no 12 v. so I have concluded that somehow along the line of the ground going to the light and buzzer I am losing it when I turn my key on. I had to wire most of the dash and stuff back up when I got the car so maybe I have something backwards. does anybody have a diagram that shows where the ground wire for the fasten seat belt light and buzzer goes to.

 

[72RoadrunnerGTX]

Don’t have a ’73 wiring diagram to verify a change, but in ’72 the seat belt waring system is triggered by the parking brake switch.

 

[midnightrider1818]

Well i have 12 v to relay put car in park or neutral you get a ground to relay which im sure what triggers it and sends power to light and buzzer. Problem is when i switch ignition on i lose the ground lol. I have ground with ignition off

 

[idrivemopar]

You shouldn't have ground when in neutral or park, only when in gear, reverse, 1st, 2nd, or 3rd, on an automatic, which I am assuming you have and the seatbelt is not fastened. As far as something unplugged, is the connection to the seatbelt light on the dash plugged in? Its behind the cluster, two prong male and female connection the goes from the seatbelt light through the dash pad to behind the cluster. Also, check the passenger side seat switch and both seatbelts to make sure they are plugged in. Also, is the seatbelt relay attached to the dash or just hanging? It needs to be screwed to the dash, for ground.

 

[midnightrider1818]

well I think I have it figured out. I tore apart the relay and found out how it worked. first one was bad and second one I think was too. there is two contacts in there. looks to me like when in neutral or park the relay gets a ground and pulls the contact down which does not allow a ground to the buzzer/light. when you put in gear it loses ground to relay and closes the circuit. looks to me like relay gets a ground through casing which goes through relay and through seat belt switches to light and buzzer. in other words. relay closes the ground circuit for system.