Cluster swap question

[ray_mcavoy]

Originally Posted by 2120

Currently in the process of swapping out my 77c10 with gauges over to a 78 tach cluster. When re-pinning my brake ground in pin #6 over to #17 there’s already a tan wire in the # 17 pin location. Also the #6 pin has 2 tan wires going into it.
My question in is do I combine #6 to #17 and have a total of 3 tan wires in that spot? Or do I just leave the #6 tan wires out altogether?

The 77 gauge clusters had two different locations for the "brake" warning light depending on the cluster. The regular (RPO Z53) gauge clusters had the brake light located in the lower/left corner and it was connected to pin #6. The clock (RPO U35) and tach (RPO U16) options make use of that lower/left opening for the clock, or to re-locate the fuel gauge. So they re-locate the brake warning light to a window at the bottom of the fuel gauge or tach faceplate where it is hooked up to pin #17. To make the wiring compatible with the different cluster styles, the 77 wiring has the tan/white (circuit #33) brake warning light wire running to pin #6 and a then second branch running from pin #6 over to #17. That's why you are seeing 2 wires on #6.

The 78 (and later) gauge clusters all have the brake warning light in a window at the bottom of the fuel gauge (or tach). The lower/left opening is no longer used for the brake warning light. So these clusters all use the pin #17 connection.

So you can leave the pin #17 connection as-is. But the 78+ gauge clusters make use of pin #6 as a +12V feed so you can't leave that one as-is.

I'd recommend extracting pin #6 from the connector (leaving the wires attached) and insulating the terminal with some heat shrink tubing. That will keep the brake warning light circuit to pin #17 intact and it will free up the #6 cavity to accept the +12V feed wire.