I'm half way through installing boost and oil temp gauges. The boost gauge is mechanical and only needs a dimmer hookup (so it lights up when the lights are on). The oil temp gauge is electric so it needs 12V power as well as a dimmer. I've read the past threads and it looks like I can tap a dimmer wire from the bundle near the fuse box. What is a good wire to tap the 12V power to the electric gauge that is always powered when the key is on? Thanks.

 

Ok after another day of searching, I found some more info on the wires. The dimmer wire for lighting will be tapped into the grey/red wire in the big loom going through the firewall. After reading the how-to for the Moss gauge kit, it looks like there is a light green wire in that same loom that can be tapped for switched power for the electric gauge. Does this sound right?

 

grey/red wire is correct for the illumination.

The electrical diagrams in the Haynes manual shows a green wire as one of the switched lines coming out of the ignition switch. I don't know if it is the same as in the loom you are referring to, but it is quite possible.

 

EASIER WAY FOR DIMMING LEAD:

1. Remove the tach from the steering column.

2. Unplug the wiring harness from tach. Slit the fuzzy black tape covering the wires CAREFULLY to expose the wires.

3. The gray/red wire in THAT bundle is the positive for the gauges.

4. I used a tap - $2 at Radio Shack or you can carefully slit the coating with a NEW Exacto blade and splice it in. Coat w/ electrical tape.

5. Use the slit fuzzy black tape to coat and reinforce the splice - I used a small zip-tie to reclose the black fuzzy tape.

Reinstall the gauge and you're good to go. Gauges will dim along with your OEM tach/speedo. This iS MUCH easier than doing it at the loom because there's only ONE wire (there are two in the lower bundle and the SMALLER GAUGE wire is the one that you need to tap there) and this way you don't need to crawl under the dash. Wirs can be tucked into the plastic shroud covering the steering linkage and are totally invisible, even with the knee bolster open (in case that's important to you).

Use any screw tapped into metal for the ground wire.

 

Thanks guys. I guess tapping into the wire right at the tach would be easiest. I will still need to tap the green wire to power the electric gauge but at least there's only one of those

Hopefully I can get it all done by the end of the week.

 

Well I got the lighting done this morning. I got a tap for 12-18 ga. and it was a little too big for the factory wire. I had to use a utility knife to strip the insulation off so the tap only needed to make contact with the electrical wire. It worked great and everything is back together. Now, all I have to do is tap into the green wire for switched power, ground everything, and run the wire for the oil temp sending unit through the firewall grommet.