What's this yellow box?

[Bruce Wingate]

1984 k10 with full gauges

View media item 9658
I'm tracking down some wiring issues and ran into this. I haven't traced the source wires yet but there is a terminal that connects to the speedometer neat the speedo cable. What the box /circuit for?

 

[78C10BigTen]

Hmmm.... unsure

 

[FireTruck1984]

You must be registered for see images attach

 

[Blue Ox]

I believe that is the speed sensor for the cruise control.

 

[bucket]

I believe that is the speed sensor for the cruise control.

Yep. In later years, it provided the VSS signal for the TBI injection too.

 

[Matt69olds]

As mentioned, speed sensor for the cruise and ecm.

On the later trucks, there is another module that looks very similar to the yellow one, except it’s a greenish color if I remember correctly. That’s the remote lamp driver, it’s designed to turn on the check engine light in the event the ECM loses power, complete failure, or for some other reason isn’t able to turn on the CEL

 

[dvdswan]

Is the Flux Capacitor noise suppressor.

 

[Bruce Wingate]

Thanks all.

Cruise control is further down the list. Right now I have to figure out why I don't have power to a lot of things like dash lights, radio, clock. I'm going to dig for a few days and then I'll probably be back with more questions.