wayneblackwell1000: The white connector is X121 and is only used on the M60/M62 840Ci with cruise control. It's purpose is to connect the brake pedal switch to the cruise control (tempomat) module. On the 850i/Ci/CSi it's not required because the cruise control is integrated in the EML (electronic throttle control).
The blue connector is somewhat of a mystery. The picture is vague, but it looks like a 12-pin connector. If your 1991 was built after June it could be connector X74. Is your car perhaps not equipped with an airbag (X74 normally connects to the SRS airbag module)?
Anyway, neither of these plugs is related to the instrument cluster. First make sure the instrument cluster is getting power. Check fuses F1 and F17 in the front power distribution box. If the fuses are okay, remove the instrument cluster and measure voltages over following pins of the 26-pin connector:
- 21 to 15: always 12 V
- 23 to 15: 12 V as of ignition key position I.
If those are okay, the instrument cluster test should work. If it doesn't, I'm afraid it looks like a faulty instrument cluster.