Gauges and bright/dim switch

[Tombo]

I have an 84 k5 blazer I'm putting back together that was my grandfather's. Only gauge that I could get to work was the temp. Picked up a cluster, bezel, dash pad and passenger dash trim for 40 bucks from an 89 suburban. Only difference I see was the clock my original gauges had. I installed them today and they seem to be working right. The speedo try's to go backwards when I'm in reverse. Is it suppose to do that? It also jumps around a little when I'm cruising around 55. Never fooled with a cable driven speedo so I'm clueless. Also, what is the black 3 wire connector that's held by a screw beside the speedo? Looks like 2 little lights inside it.

Next question is the bright/dim switch mounted on the column. It has a rod that comes up through the column to the multifunction switch. The actual rod isn't connected to anything and I don't see what it could hook to. May be missing something there? I've searched but haven't found what I'm looking for yet

 

[Rusty Nail]

The turn signal stalk is the bright/dim switch. Pull it towards you to click and release. Note blue indicator light in dash.

 

[Tombo]

There's a rod that connects to it somehow. The actual switch is mounted about half way down the column.

 

[Tombo]

After alot of searching I found what I needed on the dimmer switch. I actually went off in my works junkyard and tore down a late 80s camaro column to see how it worked. I was missing the dimmer rod actuator. Ordered a new one and got it all back together and working.

 

[Matt69olds]

The 3 wire piece next to the speedo cable is the optical sensor for the vehicle speed sensor. It plugs into the speed buffer, which provides a input the pcm and cruise module.

 

[Matt69olds]

The speedo needle jumps around because the speedo cable is probably dry. Pull the cable back out, clean it, and lube it with light grease.