Dimmable Gauge Lighting

I've installed a four gauge pod (about $40 or so from Summit Racing) where the rear view mirror would normally be in our '06 2500 Long and Tall Cargo containing the following ISS Pro gauges: voltmeter, transmission temperature gauge, boost gauge, and exhaust gas temperature gauge. I'd like to hook up the power feed for the gauge illumination so that it is dimmable from the instrument cluster + and - buttons. From reading the service manual I see that supposedly:

"• Panel Lamps Dimming Control - The EMIC provides a hard wired 12-volt Pulse-Width Modulated (PWM) output that synchronizes the dimming level of all panel lamps dimmer controlled lamps with that of the cluster general illumination lamps and multi-function indicator."

"The EMIC also provides a Pulse-Width Modulated (PWM) panel lamps dimmer output that can be used to synchronize the illumination lighting levels of external illumination lamps (up to about 23 to 30 watts) with that of the EMIC."


From reading previous threads here, specifically:

http://www.sprinter-source.com/forum/showthread.php?t=668

and

https://sprinter-source.com/forums/showthread.php?t=601&highlight=dimmer

and

https://sprinter-source.com/forums/showthread.php?t=601&highlight=dimmer&page=3

... it appears that I want to tap into a GY/DG/RD wire located at, or around, S253.

My questions are:

1. Do I have the location and wire correct ?

2. Does this wire indeed work as advertised - providing a PWM output that will dim or brighten small 12v lamps via the + and - buttons on the instrument cluster ?

Thanks in advance.

rlent said:

1. Do I have the location and wire correct ?

2. Does this wire indeed work as advertised - providing a PWM output that will dim or brighten small 12v lamps via the + and - buttons on the instrument cluster ?

Click to expand...

1. Yes. that's is the illumination wire. All the switches on the console have that wire for night time illumination.

2. This I don't know because I've never noticed it when adjusting my brightness. I only know that you can control the brightness of the readout when the lights are off or on.

Since every switch on the console has that wire, it's just a matter of connecting a DC meter to the wire and GND (brown on the same switch connector) and measuring the average voltage output.

'O Sick1,

Hooked up the multi-meter and the average voltage output is ...... well, just average.

No change in voltage whatsoever when the + or - buttons are pressed ...... which sorta makes sense in that the LED's on the switches aren't exactly capable of blinding ya .....

On the upside my gauges are all amber to match the stock illumination and they aren't all that intrusive anyways (I say that now, ask me later after an all-nighter thru the middle of nowhere ...... )

The only thing I can think of is that the service manual is referring to illumination of the gauges that are internal to the EMIC - or that there is something on the inside of EMIC that one would have to tap into to get a dimmable output.

At any rate I'm unwilling to spend any more time on it as I still have a bunch of other stuff still to do.

rlent said:

Hooked up the multi-meter and the average voltage output is ...... well, just average.

No change in voltage whatsoever when the + or - buttons are pressed ...... which sorta makes sense in that the LED's on the switches aren't exactly capable of blinding ya .....

Click to expand...

I can backup your finding. Adjusting my gauge brightness had NO affect on the console switch LED's or the window and mirror switches.