Help Wiring New Switch into Dimmer (Rheostat)

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Nov 11, 2007
Nashville, TN
I'm trying to wire in my new compressor switch and I was just going to grab power for the light of the switch from the switched dash lights right from the dimmer (rheostat).

So I see there is a plug going into the dimmer with 3 wires.


I've obviously been able to surmise that the white/black wire is the ground, and have been using this as the basis of my tests. However, when I test either the white/green or green wires with my meter on DCV, I'm getting power from both of them. Note when I'm testing, I have the ignition in "ON" and the headlights on, thus the dash lights would be lit up at this point (not now cus the dimmer is unplugged).

Anyways, I thought one of these would be a dead line that feeds the lights only when the rheostat is plugged in... so why am I getting power on both?

Anyways, the end result here is to find a place to wire in the + for the lighting on my new switch so that it will dim with the rest of the dash when dimmend and turn off when they are turned off. If I should not be jumping in here, then where?

Bump for electrical Gurus!!!
I know there is a thread here that explains it better than this. I think what you have is a positive, negative and ground. Not sure which is which without pulling the wiring diagram.

I think it has been much discussed on subtank overhead console threads.
Don't know if this is any help but when we wired the acc harness switch from slee there are two green wires on the switch pigtail and those two wires connected to the other two green wires in the harness. This made the light go on and didn't make any difference which way you put then together. The harness has to be plugged into the dimmer to complete the connection. The wires in the harness for the 94 are B&W stripe with a silver band, G with silver band and G&B with a silver band. Might not be the same with a 96. HTH
I am not familiar with that switch configuration but I think what you need to do is connect a wire from the green to one side of the switch bulb filament and a wire from the other side of the switch bulb filament to the white/green. The order of the filament wires does not matter. The rheostat provides the path to ground on the white/black. If you just run a wire from the green or the white/green to the bulb and the other side of the bulb filament goes to ground, then the bulb will light and not be able to be dimmed. $02 worth. HTH.

I worked with this a little more tonight, but I am still having issues.

What I did to test everything was hook the switches' bulb connection (+) into a verified dimming + on another switch and run the ground of the switch assembly to the nearest ground connector.

The switch lights up now when the headlights are on, but it is opposite of the rest of the dash... so if the dash lights are on full, the new switch is dimmed out, and if the dash is dimmed out, the new switch is bright as can be.


Well I figured it out... just idiocy on my own part and non-knowledge of electrical wiring. The ground for the light must be in the ground for the rheostat as well as the positive lead.

For my installation, I cut into 2 of the 3 lines going to the rheostat. The Green/grey dotted line is your rheostat ground, and the white/grey spotted/green striped is your rheostat +

I would not recommend making your cut into the system here, as working space is tight and the wires are very short. Cut into the dashboard lights on another switch. The wire colors seems to be consistent with what I stated above on other switches.


Glad you figured it out....I am looking to wire up my gauge lights and need to pull power and would like to dim them also so I guess what you are saying is pull power from another dash light source??? Any advice where??


Glad you figured it out....I am looking to wire up my gauge lights and need to pull power and would like to dim them also so I guess what you are saying is pull power from another dash light source??? Any advice where??


Yeah... your best bet for these is gonna be the top row switches in the center, as those have a bit of slack for you to work with. Just splice into 2 wires on one of the switches' connectors that you don't use much (just in case you mess it up ;))

As a rule of thumb, generally Green/Grey spots is the rheostat positive, and White/grey spots/green stripe is ground (I believe). Test before you commit though, as it may not be entirely consistent throughout the dash. Someone correct me, but my guess is that it doesn't really matter which way you hook into these lines, since the bulb is the pos-ground connector anyways...

Guess I will give it a try tommorow and will post if I have any luck. It will really depend how motivated I am when I wake up.

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