Cluster lights

[alexios98]

Hello everyone,

I recently bought an e30 1988 325i and some of the cluster lights are not working. To be more specific the lights of speedometer and tachometer are not working when I turn on the lights. The indicator lights, handbrake lights etc work fine. I already did a bypass on the rheostat in order to have the brightness to the max but that didn't help. I checked all the fuses and they are fine. I need to mention that the previous owner completely removed the air condition and the radio if that matters.

[alexios98]

Forgot to mention that the clock's light and hazard button light turn on when I turn on the lights

[Vincenze]

There are 2 orange illumination lights at each side.
They use bigger 3W bulbs.
If the bulbs are new, but they don't light up, then there can be a bad contact.

[alexios98]

I checked the bulbs and they are fine. I did more checks on the cable's pins. I discovered that my yellow cable (c3) is completely removed. From the cluster's board i found out that the bulbs take power from white cable, pin 23 and 24 (i think 24 is ground). In any case pin 23 gives 5V only and pin 24 is 0.08. I belive that 5V is not enough to power the bulbs. The next step is to make the clock's light cable split and connect the 1 end to the clock and the other to pin 23. If you have any other ideas or suggestions please let me know.

[alexios98]

Update: I did the splice from the clock and connected it back to the clock and pin 23, but still not working (clock's light is working fine). I bought new bulbs (12V 3W) and replaced them but again nothing. I checked again and pin 24 is indeed ground but it seems that it's free. Anyone knows if the bulbs need ground or not?

I found this diagram below but i don't understand it fully. If anyone can advice it would be great.

[Vincenze]

You can use any battery or power supply to check the lights. For example, a 5V battery. 5V should be enough to light up the bulbs.
Connect - (ground) to the contact 24 of the C2 connector (white) and + (+5V) to the contact 23 of C2.

The ground (contact 24) is connected to the light switch, which is a variable resistor. By changing the resistance and voltage, you make the lights brighter or dimmer. If the voltage doesn't change when you rotate the knob, then the light switch may not function correctly.

If that doesn't work, try to trace the tracks from these contacts on the PCB.