Installed a Tach

[87ChevyR10]

I bought an el cheapo tach from O'Reilly's last weekend and installed it. As a temporary measure, I have the tach backlight spliced onto the low-beams wire from the HL harness. This way, when HL's are on, so is the tach backlight. However, I'd like to move that backlight wire to the HL switch so the backlight stays on when switching to high-beams. Which wire should I splice into?

Thanks!

 

[chengny]

Don't use either of the headlight circuits (or the parking light circuit). You might want to consider tapping into the instrumentation lighting circuit. After all, the tachometer is generally considered to be an instrument/gauge type component.

Unless you have some reason for it not to be, the tach backlighting should be dimmable - and controlled by the rheostat. If done that way, it will brighten/dim in synch with all your other backlit devices (IP/HVAC/Radio).

You can splice into that dimmer controlled circuit in a bunch of convenient places:

1. At the H/L switch (the dark green 44 lead is the dimmed feed to the fuse block)

2. The same dark green wire - at the fuse block end

3. The gray 8 wire coming out of the block:

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The gray 8 wire goes several places. It goes to the instrument panel, the HVAC panel, the radio and also to the convenience center (used to activate the alarm buzzer for a "headlights left on" condition?)

 

[87ChevyR10]

Thanks! I only tapped into hl wires as a temporary measure.