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I believe I have asked this before, but I don't remember if it was this forum or another. I have a 1975 coupe. The car had the interlock system. Over the years, everything has been either removed or disconnected. I do not have the interlock relay on the firewall. When removing the interior, I found the (logic box?) in the rear compartment. Don't know what it is doing at this point or if it is working at all. There is nothing under the seats other then the seat sensors and connectors. There is also the connectors for the seat belt buckles.
Now, here is what I would like to do and I like to know is it possible:
I would like the dash light and buzzer in dash harness to work when seat belt is off
I would like to use the current harnesses to have seat belt working as if it were a non interlock car
Is it possible with the wiring I have in place now?
My knowledge on seat belts and the associated warning buzzer is for the 1973 cars. On 1973 cars there was an electrical connection that ran through the seatbelt (at the retractor), so that the car knew the seat belt was buckled to the receiver (located on the tranny tunnel). The passenger side had a (weight system) in the seat bottom to detect if there was someone in the seat. As far as I know, there are no replacement seatbelts with the electrical connection being made. I used a small electrical timer connected to a buzzer and the seat belt warning light (in the center gauge cluster), tied to the ignition post on the fuse block. So whenever my car is started, the buzzer and light comes on for approximately 15 seconds and then goes off. The car doesn’t know if the seat belts have been buckled. Hope this answers your question.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Originally Posted by Eliredandblack
My knowledge on seat belts and the associated warning buzzer is for the 1973 cars. On 1973 cars there was an electrical connection that ran through the seatbelt (at the retractor), so that the car knew the seat belt was buckled to the receiver (located on the tranny tunnel). The passenger side had a (weight system) in the seat bottom to detect if there was someone in the seat. As far as I know, there are no replacement seatbelts with the electrical connection being made. I used a small electrical timer connected to a buzzer and the seat belt warning light (in the center gauge cluster), tied to the ignition post on the fuse block. So whenever my car is started, the buzzer and light comes on for approximately 15 seconds and then goes off. The car doesn’t know if the seat belts have been buckled. Hope this answers your question.
That's interesting, what kind of electrical timer and where can I get one?
Can you explain how you wired it, (schematic?)
I will include a picture of a 12 volt DC timer purchased on EBay. Connect 12 volts POSITIVE (find the terminal on your fuse box labeled IGN) to power the relay., then find a common ground. Connect 12 volts Positive to one side of the relay and the other side of the relay to the light and any 12 volt buzzer. Connect the common ground to the negative side of the light (if it’s a LED) and buzzer. If you need me to draw a schematic, let me know. I put the relay board inside a big piece of heat shrink and then placed it behind the Map Pocket.
I bought and extra for Turing off the trunk light on my Pontiac. Get two, there are inexpensive
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Great idea!
Thanks for the reply. That sounds like an easy and worthwhile project.
You described the wiring very well but if you have the time a schematic would help.
Thanks again.
Disconnect Battery before making any connection. You may want to employ an inline fuse for added protection. Most auto parts stores have them in electrical section. Use a spade connector to attach the Positive Wire to “Stud” marked IGN on the fuse block. You will have to cut both wires going to the “Warning Light” in the center cluster, then solider new wires that will be connected to the timer. Use heat shrink to seal ends of factory harness wires going to “Warning Light” as well as all other connections. My schematic was done quickly, i am headed out to search for No Ethanol Gas.
Seat Belt System
