dash gauge dimmer wire

[mdutton11]

Having a heck of a time trying to get my gauge background lights dimming off the RF / FFR supplied headlight switch. They will switch off and on with the dash mounted dimmer potentiometer but not dim. They will dim with the small potentiometer that FFR says to tape in the full on position. The red indicators stay on all the time. Running Russ Thompson turn and IDIT headlight / turn relay. Can anyone tell me which wire will dim the gauges from the headlight switch?

[edwardb]

RT turn signal and IDIT headlight relay have no effect on the dash lights. IDIT relay has nothing to do with turn signals either BTW. Not sure what you mean by red indicators. But nothing in the dash light wiring should be causing that. Unless something is really wired wrong.

Assuming you have the RF headlight connector plugged into the supplied GM/Delco style headlight switch, the white dash lights wire in the dash harness is what you use. You need to turn the headlight switch all the way to the left (just before the added detent to the courtesy light setting) to supply full 12 volts to the white dash light wire. From there, if you have the style gauges with the inverter and separate dimmer knob, the white wire gets attached to that. Later versions of the Speedhut gauges, if that's what you have, no longer have the separate inverter and separate dimmer knob. They changed to LED backlighting.

[mdutton11]

Red indicators are the needles in the gauges that show what level the gauges are at (sorry about not having the proper wording).

Yes the RF connector is into the Delco switch and all wired according to the RF wiring instructions (IDIT aside but as you said that should not be an issue - just trying to tell you all what my setup is). I can control the background dash lights with the separate dimmer knob which I assume means it is hooked up correctly but cannot control the background dash lights with the headlight switch.

I don't mind mounting the separate dimmer switch under the dash as it will rarely be used but I also want it to control the background light on my aftermarket switches. I have the input for them but need to know what to connect them to.

[JohnK]

In addition to plugging in the RF connector to the headlight switch, there should be another black ground wire with a spade connector that plug into a tab on the side of the headlight switch. This grounds the headlight switch and allows the dimmer function to work properly. Check to make sure that this is plugged in so that the headlight switch is grounded, otherwise the dimmer won't work.

[Andrew Davis]

Had the same issue. At the lower edge of your oil pressure gauge face it reads REV T, that indicates the backlighting is LED. The pot on the headlight switch is for incandescent lights. I tried an aftermarket led switch, suggested by speedhut but ran out of patience and removed it. Good luck. Andy

[edwardb]

Red indicators are the needles in the gauges that show what level the gauges are at (sorry about not having the proper wording).

Yes the RF connector is into the Delco switch and all wired according to the RF wiring instructions (IDIT aside but as you said that should not be an issue - just trying to tell you all what my setup is). I can control the background dash lights with the separate dimmer knob which I assume means it is hooked up correctly but cannot control the background dash lights with the headlight switch.

I don't mind mounting the separate dimmer switch under the dash as it will rarely be used but I also want it to control the background light on my aftermarket switches. I have the input for them but need to know what to connect them to.

OK. The red needles on the Speedhut gauges aren't dimmable. Although their fed from the same RF white gauge lighting wire, they don't go through the Speedhut inverter and separate dimmer knob. So they will just switch on and off when twisting the headlight switch knob/dimmer function. Does sound like you have the older style Speedhut gauges (e.g. non-LED backlighting) since you have the inverter and separate dimmer knob. The newer LED backlit version has been out for a couple years. So either your kit is a couple years old or they're still finding the older version somewhere. Would be good to confirm as Andrew Davis suggested in his post.

Assuming you do have the older style gauges, it's not going to be possible to dim your switches with the headlight knob without affecting the gauges. At least not without modification to the wiring harness. One thing I can think of -- if you're up to such a thing -- is to change the standard gauge feed at the headlight switch. Move the existing gauge lighting wire to a different switched +12V source. Like the parking lights. Use that to power the Speedhut gauge lighting via the inverter. Then add a new wire to the headlight dimmer function to power your switch lighting. Just an idea/theory. Haven't tried myself. But should work.

Having said the above, just a comment based on actual experience. I've found over many years of driving we don't drive ours a lot at night. Not intentional necessarily. Just how it works out with events, cruising, how we use the cars, etc. When we do drive at night, I rarely mess with the dimming functions. Whatever they are out of the box is usually just fine. I typically have everything up full bright by default. Don't know how much I'd recommend trying to mess with what you have if you aren't real comfortable with wiring and electrical.

[mdutton11]

KISS right - Keep It Simple Stupid. You are both right and I have wasted way too much time on this. Dim the gauges with the small potentiometer mounted under the dash and don't worry about the accessory switches (buttons). Thanks!