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I am a newbie and I am trying to get the seat belt system to work properly. It is a 1975 coupe. It has both the seat and buckle switches , seat belt warning buzzer, seat belt dash light and what appears to be the relay under the shift console. I know that in early 75, they installed the interlock system in some of the cars. Based on information someone had given me, the vin number indicates that it had the system. I can not determine if it actually did. There is nothing attached to the firewall in the engine compartment. There does appear to be two bolts on the firewall that don't seem to have any purpose.
What I am trying to get the system to operate. The color wiring diagram does not show the wiring for the interlock. i am assuming this is a harness with the interlock wiring. However, like I said I can not trace anything to the engine compartment. Is it possible to wire it with the current harness and if someone could help me, I appreciate it.
I have the relay under the console,( just purchased it) the old one was burnt out,the buzzer is located in the harness behind passenger side dash and I do not have the part n the firewall, but it looks like it may have been there , there are 2 bolts there
I put in relay, but it did not work. My guess is that I have to cut the green wire at harness connection. I think i found connection, but i am not sure. in the information Interlock and Buzzer disconnection, in number 3, it says see ilulsrartion, by chance do you have the next page or illustration of the connector so I can be 100% sure. The connector i see has a green, a yellow and 2 orange leads. Thanks Vinnie
Hello VinniePG--the wiring diagram for this seat belt interlock system is contained within the wiring diagrams located in "1975 Chevrolet Service and Overhaul Manual Supplement". All of the components for the system (starter interlock overide relay, interlock relay, seat belt warning buzzer, buckle switches, seat switches, etc. are shown on this wiring diagram. Unfortunately, as you have learned, aftermarket wiring diagrams are incomplete and leave some of the components and their associated wiring off.
If you give me a few days I will scan these wiring sheets in for you and PM them to you.
If you go to the NCRS website and search "1974 seat belt starter interlock" a bunch of threads come up. Many before you have tried to troubleshoot this pesky system. No need to reinvent the wheel. Learn what you can from their knowledge.
Last edited by '73and'75; Apr 6, 2021 at 11:32 AM.
Reason: spellin'
Peter: I had a few minutes and I wanted to check something. This is what I found out so far. The SB light in the console has power to it, the Buzzer connector has power to it. However, when turning on car, neither of them work. I checked to see if any of the seat buckle switches are getting power. None of them are getting power.. I don't know if the fact that i have the seats removed have any correlation. I would think that thh seats out should have no correlation because I am checking the switches. It looks like the power for the seat plugged into the anti theft flasher/relay in the jack compartment. could these be part of the problem? Even if the rear was getting power, why wouldn't the buzzer or light come on if they are getting power? Could it be the green wire? I know i am asking you to try and resolve the issue, but like I said, I am new to this and electrical is not my strong point. Thanks Vinnie
Seat Belt System
