05 Sierra HVAC Control Issue

[jlamb18]

I had some bulbs out in my HVAC control module so i decided to swap them out with some new ones. After I got them all soldered in, I plugged it in and the bulbs lit up for a few seconds until smoke started coming out of the back and the bulbs turned off. I started looking for a short somewhere and found a start piece of solder touching two leads together on the board and I figured that was the issue. I removed that piece of solder and thinking that I was all set I plugged it back into the truck, and smoke started coming out again, but this time, the LCD screen went out as well.

 

I sorted out the issue with the short by testing the bulbs with a power supply, but when I plug it into the truck there is still no lights or LCD screen. I found the pins that should deliver the power to the bulbs and checked it with a multimeter and there is no current.

 

My question is, is there a certain fuse that would specifically control the power to the LCD and bulbs? I checked all the fuses labeled HVAC and they were all good. Could the issue be with the dimmer switch? I am doubtful of this because all of the other backlights work elsewhere. Any advice would be greatly appreciated.

 

Thanks

[Heavy 5.7]

I found the pins that should deliver the power to the bulbs and checked it with a multimeter and there is no current.

What happens when you follow that circuit back?

[Coby7]

Something went wrong here....

[jlamb18]

When I plugged it in the first time, the functions of the HVAC all still worked, but now nothing turns on when I press the buttons... Could this mean that I fried my HVAC control module? Or is the issue within the truck's wiring?

 

@Heavy 5.7 I haven't, I am not very familiar with this type of stuff and I am not good at following wiring diagrams

 

I am just trying to figure out if the issue is with the controller or with the truck, just so I can go from there

[Coby7]

Looks so easy on YouTube.

 

The LCD display is supplied indirectly from the dimmer but backlighting bulbs are supplied directly from the dimming internal lighting supply, the same that supplies cluster and radio. There's an electronic circuit that dims the LCD display but I doubt your problem is with this circuit. Find out why your bulbs aren't working and all will work.