[Ruckerman]

I just recently bought a 1974 Dodge Coronet with low, low miles (32,000) at a car show and swap meet. The car was bought new by a lady who lived in Circleville, OH and just passed away recently. The car is in really great shape and although it’s a sedan and not a 2-door coupe, I like it. The car has a strong 318 V-8 and an A727 Torqueflite automatic transmission.

One of the few niggles I could find to complain about this car is that it has the Seat Belt Interlock System that was mandated by Washington in 1974 for all cars and light trucks. This system has failed in this car and the only way I can get it started is to press the Seat Belt Interlock System override switch underneath the hood.

I was a mechanic in the 1970s working for a VW dealer and I remember how hated the seat belt interlock system was and how often it failed. I also remember how loudly the public complained to Congress about it; we complained so loud and so long about it in fact that Congress actually listened (for a change) and rescinded the seat belt interlock requirement late in 1974. Thus it is only the 1974 and some early 1975 models which have this less than perfect set-up.

I have the car in a Dodge shop to have some work done on it and I have asked the mechanic to disable the Seat Belt Interlock System. He’s dragging his feet though and he doesn’t want to run the risk of getting his shop sued for disabling a mandated Federal system. I’ve told him that it (the requirement) was removed by Congress in 1974 and it is totally legal to turn off the system now, but he’s hesitant and he doesn’t want to take just my word for it. Can anyone point me to a web site that gives the official word? Or does anyone have a step by step instruction to use to disable the system if I have to do it myself?

 

[Bob Lincoln]

A Google search may show. Since the law was rescinded, it should be OK to disable it. And since it's not inspected, no one would know.

 

[B10alia]

Interesting that you bring this up-- we just had an article about it last week! According to pictures in the article, you can just unplug the connectors.
http://www.allpar.com/fix/electrical/interlocks.html
Also, from NHTSA themselves:
http://www.nhtsa.gov/cars/rules/rulings/AAirBagSNPRM/AppA.html
The Federal regulation that was amended to not require interlocks was 39 FR 38380; October 31, 1974

 

[Gerry G]

Very simple to disable the interlock. Open the hood, on the firewall towards the passenger side is a block with a red plunger on top that pushes down when the hood is closed. This switch is a part of the interlock system. Simply disconnect the wire to the switch to disable the interlock.

The switch is actually there for a mechanic to work on the motor. The plunger pulls up and locks in place so the motor can be started. Closing the hood would push the plunger down and enable the interlock. Disconnecting the wire has the same effect as pulling up on the red plunger.

Hope this helps,

Gerry G.