Dash Light Issue

[mikrsmith]

Hi Everyone.

My 2010 MKX developed an issue in which after 5-10 minutes of driving at night the Odometer and Digital climate control lights suddenly go full blaze as though the headlights were off. The NAV screen stays in night mode and all of the other dash lights are adjusting with the rheostat for the cluster lights that sits to the right of the headlight switch.

I realize that these displays are LED and therefore are using a much lower voltage for adjustment than the other panel lights, so somewhere along the line something has those two on a circuit together adjusting independently of the others.

 

Any Ideas? Could it just be some component of the rheostat that's malfunctioning after it "warms up"? I hate to spend money on a new switch assembly and it end up being something further down the line. but I find the brightness to be distracting while driving at night.

 

Thanks for any input.

 

[enigma-2]

I looked on the wiring diagram and all of the back lighting is connected together at connection point P209.

 

As to why only two of the back lights are switching is really perplexing. If all of the backlighting were going full bright it would indicate the SJB was at fault.

 

As for the odometer, all of the instrument cluster lighting is all wired together. That the odometer goes bright and the rest doesn't just makes no sense.

Edited August 28, 2017 by enigma-2

[mikrsmith]

That's why I think that those two are regulated differently somehow. They are the only LED backlit lights on the panels. LED reaches full brightness at a far lower voltage than the incandescent lights that are everywhere else. so I'm thinking they are regulated differently at some point. The LCD Nav screen adjusts with all of the other lights.

 

I'm thinking that these two specifically have a separate output on a circuit board somewhere. That's why I was thinking it could be an issue with the rheostat. There must be a separate, shared output for the voltage to these displays. Whether or not that output would be on the board in the rheostat assembly or at some other place in the dash is another question.

 

To be honest I'm thinking that it might be in the rheostat simply due to the fact that, on occasion I can adjust the panel lights all the way up, then back down and the Temp and Odometer displays will dim back down for a few minutes before going full bright again. other times, however, they are unaffected.

Edited August 29, 2017 by mikrsmith