Dimming Gauge Light Hookup/

[Roy W]

I installed a EGT gauge today and couldn't find a electrical source where the gauge light would operate off the instrument panel dimmer. I found spots that will operate with the lights, but no dimming function. I followed up on a number of other threads asking the same question, but I think they must have earlier models, as the recommended pins didn't dim for me. Short of tapping into the dash dimmer switch, does anyone know of a dimming power source for a 2005 model??

[Skip Vankirk]

You will need to get to the Inst. Panel connector.
Pin A11 will be a red wire. Splice into it for
dimming control of your new gauge. I just installed an EGT and Turbo Boost gauges. You will
have to remove the Dash Trim and then the IP, but it is relatively easy. Good luck.


2005 2500HD w/EGT & Turbo boost gauges, SeaHawk
5th Wheel

[dieseldummy]

You can always put a fuse tap on the INST fuse.

[Roy W]

The earlier models had separate "INST" and "ILLUM" fuses which would dim, but the newer models do not. It appears as though it's all combined in the fuse for the dash, and that fuse will not dim. I was just hoping not to have to splice into existing wiring. I also checked the panel under the dash by the emergency brake.

[mad]

Here's the scoop:
1. open your fuse panel
2. reach up inside and disconnect the light panel plugh from the back of the lighting panel.
3. tap in to the "brown/white" dimmer wire for your added gauges.
4. plug it back together ALL THE WAY and close the fuse panel.
5. use your truck at night
Hope this helps!

[White Truck]

Look at the Relay Block cover (the relay block is where the trailer brake controller harness is plugged into next to the parking brake) and identify where the C5 connector plugs into. It is labeled SL RIDE - 6-WAY - GRY
There are 6 pins in the relay block where this plug would be installed, but it is not used on an HD. One of the corner pins will be switched, and another corner pin will be IP dimming control. This is what I like to use, easy to get to, and no need to disturb any other wires or connectors. One of the middle pins is LED dimming, don't use that one.

[DmaxMaverick]

I've done a few of these.

The most simple access is from the harness at the headlamp switch. The wire color seemed to change with every year model I did (01, 02, 03, 05), so I will just tell you how to locate it.

Pull the dash trim, and pop out the headlamp switch (no screws, just tabs). With a v/o meter, ground the ground probe, and probe the connections (with switch attached to the harness, and turned on) for the connection that will vary voltage when the dimmer is rotated.

I suggest this way because no other components have to be removed (we know how sensitive they can be), and you will be assured of the correct circuit. You could tap the wire at the I/P, but it will be the same as this, just further down the line. Any circuit upstream may be the same circuit, but won't dim. An added bonus is the location. The H/L switch is right next to the fuse panel.

I'm moving this topic to 2500HD/3500 Accessories Forum (http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=forum;f=5).

[ 01-22-2006, 10:18 AM: Message edited by: DmaxMaverick ]

[Roy W]

I FOUND A TAP!!! In the under dash power center by the parking brake. Find the trailer brake plug in, then there are two empty slots to the right of the trailer brake. The lower right prong energizes with the instrument lights and will dim. CAUTION: There are two prongs in that slot. The one on the left is hot all the time, and the one on the right will dim when the instrument lights are on. I have an old trailer brake plug and you can pull one of the leads out of it to use to hook up to these prongs.