Background: Im doing a gauge cluster swap of an 86 into my 84, due to the differances i have to rewire the harnesses

My question is on the 86's cluster/wiring, there are two lt grey wires responsible for illumination but on the 84's harness there is only 1 grey wire used for illumination. Why is it this way and if i only hook up one lt grey wire, will i still get full illumination? In the pic you can see the two grey wires run the exact same path on the cluster.

(and the path of continues around the other side of the cluster, i could only get a pic of one side)

Thanx.

 

As long as the wire you chose to use has power when the illumination circuit is on, and the printed circuit goes to every bulb in the cluster then using only one wire will work.

When I replaced my cluster I spliced into one of the gray wires and everything works fine.

I'm not sure why they used two wires in '86, and only one in '84, but electricity is stupid. As long as there is a path for the current to follow it will get there.

The only other thing I can think of is that the other gray wire may not be a power feed. It may be used to tap the illumination circuit at the cluster for use powering another interior light. A simple test light probe of the two wires with the cluster unhooked and the headlight switch on should tell you if this is the case. If they both have power then use the one that is most convenient. If they don't just tee the one that doesn't into the one that does and then back into the cluster and everything will work like it's stock.

 

i went ahead and just used a 3m connector to split a second wire off of the single grey so i could run both wires to the cluster, lights up just fine