I'm hoping someone may be able to shed some "light", ha ha, on this little mystery. I have a 1994 940 wagon. I replaced the shifter light in the centre console. Soooooo when the rheostat is fully on, the dash lights and radio, heater controls, etc. are fully illuminated the shifter light is completely off. When the rheostat is at it's lowest setting, no illumination on dash lights etc. the shifter light is fully illuminated and it dims as the dash lights grow brighter using the rheostat and vice versa. Any clues of how to solve this? I feel it may be simple but I have never seen anything like it. Any and all input and comments always appreciated.

 

sounds like the shifter light is wired from the dimmer circuit to +12 rather than to ground ? htats about the only thing I could think of which would do what you describe.

 

Thanks for that input, I will see if I can figure that out by following wires from the bulb.

 

that, or its not grounded properly... if several circuits 'minus' side are tied together but not properly grounded, then current can flow from one to the other backwards, this could do exactly what you're describing.

AND, according to the 1994 940 wiring diagrams, the shift indicator is powered off fuse 22 and NOT connected to the dimmer at all.

the shift indicator lamp goes to a 4-pin connector C139, pin 3 is blue or black, and should be ground, pin 1 is grey and should be 12V from Fuse 22. This connector is somewhere right under or near the shifter.

all the control lighting, and many other circuits, go to a ground point on the right side of the passenger footwell, just forward of the lower right hand door hinge.

 

Great info. Thanks very much. I have had the center console cover off a few times now it shouldn't be difficult to get to any of those areas to check. Much appreciated.

 

I know people rarely post the solution but I always try to. Turns out the solution was very simple. Fuse #22 was blown. Now why when the fuse blows the light on the shifter work in reverse rheostat mode I don't know. However problem solved. Now on to the gas gauge mystery. Thanks for the info.