450 Cluster Backlighting Inoperative

[Ant2ant2 1]

Hey Guys, 

 

So the backlighting on my 450 cdi does not work on my cluster, when using the switch the tach light and all of the HVAC lights illuminate except the cluster backlighting. All of the warning lights operate normally and the LCD display functions normally as well. I pulled the cluster out and pulled it apart to diagnose if any of the motherboard cold solder joints and while tracing wiring to the small lights, I noticed that there are 4 small lights that are the backlight for the speedometer and these lights are actually its own separate circuit that is actually controlled by the small black 3 pin connector for the cluster, not the 18 pin large connector. 

 

So while testing these wires using a power probe, i figured out that the 3 pin connector is black for ground, yellow for the top 2 bulbs, and green for the bottom two bulbs. the cluster bulbs and circuit actually work normally and the circuits are working in the cluster. So I tested the connector to the vehicle.

 

Ground - Has good continuity to battery ground.

Yellow - Has 0volts when using switch to activate lights

Green - Has 0volts when using switch to activate lights

 

Now to my question. . . . . . . . .  .Does anyone have any wiring diagram or have any idea where this black 3 wire connector on the back of the cluster goes to? I cant not seem to find any wiring diagrams for this connector and I have no idea where this harness goes to (SAM or switch). 

 

I don't know if there is a fuse specifically for the cluster backlight for this connector or where it goes. I can only find the schematic for the 18pin connector and that's for the illumination of the LCD and warning lights. Some please help. 

 

Thank You.

[Leadwing 535]

There is a switch below the radio that severely dims the backlights on the dash.  Unless it is totally dark out with no other light coming into the cabin, you will think that they are not working.  In total darkness, you will be able to see them.  It is possible that this switch may have been flipped by accident. 

[Ant2ant2 1]

Does that dimmer switch control only the cluster lights because I was under the impression that it controls all of the lights functions and dims everything even the tach and hvac controls? I will go and test this tomorrow to see if this gives me 12v at the two wires on the black connector. I will be super pissed at myself if that fixes it. Haha

Edited June 22 by Ant2ant2

[MikeT 689]

instrument lights ONLY

[MikeT 689]

Makes the radio go brighter too, duh to the electrical designer on that one.