My odometer is blank, the backlight comes on, but the digits do not light up. I have replaced the capacitors on the back of the speedometer and checked the grounds. The only other problem area is the flex board where I have found a spot that doesn't have continuity. Below you can see J4 ODO ILL. Does anyone know exactly what component is behind the flex board? I am assuming R = resistor and D = Diode, but what does J stand for? How do I remove the flex board without damaging it?

 

Is this a multi-layer board?

 

I de-soldered the terminals and removed a diode from the back side of the board. Can anyone identify this diode?

 

sometimes the connector on your alternator somehow loses connection. That would lead to something like what you see.

 

I traced some wires and found that the red wire with green stripe provides the ground for the odometer illumination. Since the diode is testing open, no current makes it to ground.

 

I just hooked up the cluster and this ODO ILL is only for the back light. With the key to on it provides approximately 1v to the back light, and with the parking/driving lights on, 12v is applied to the back light. So... I'm halfway there.