problem with gauges and heater

[robby41]

just picked a 1987 325e and when you turn the car on the heater and gauges will all work, but once the car turns on the heater, tach, gas gauge, and temp gauge shut off
any ideas of what it could be
any help needed thank you!

[locar]

did you try taking out the cluster and inspecting the SI board?

[robby41]

what do i look for on the si board?

[Jean]

Bad batteries