Under the dash of my 82 El Camino there is a yellow box about 3"x1 1/2"x 1/2 with 3 wires molded together and about 1 foot long with a little plastic thing on the end that looks like it might have little tiny light bulbs in it. Those 3 molded together wires are green, black and red and they can't be unpluged from the box. There is a plug with 3 separate wires black with white stripe, pink with black stripe, and a brown one that plug into the box on the other end.
What is this?
L.D.

Can you post a picture?

Vehicle speed sensor buffer.

Hey Robert do you know how that buffer works?

Hey Robert do you know how that buffer works?

Well, in a very general way, yes. This type of assembly is used on cable driven speedos, it has an optic head that mounts on the speedometer and
senses speed through a light beam and reflector plate inside the speedo.
The buffer converts the light signal to a 2-pulse square wave signal that the ecm understands.

Thanks Robert. I always though that GM sensed speed for the Cruise Control thru a mechanically driven generator.

Thanks Robert. I always though that GM sensed speed for the Cruise Control thru a mechanically driven generator.

Some do, through a cable driven signal generator.