# Service indicator board, replace

Remove instrument cluster

screws from rear of cluster |
Squeeze and pull out coding plug |
Lift instrument carrier off housing. |
CAUTION: Take extreme care not to damage face of instruments while removing. Place carrier face up in a safe location.
Remove single silver Phillips screw from retainer in center of housing.
Gently and evenly slide circuit board out of housing.
CAUTION: Circuit board is a tight fit, it must be removed evenly or it will stick. Do not use force or pliers to remove.
Circuit board consists of two pieces. The service light board, a small section attached vertically to the main board, containing the service indicator LED's. And the "battery board" which is the main board and controls the activation of most instruments and the service indicator lights.
If your service indicator lights are the only problem, you can remove the small light board and discard it. However, if you have instrument malfunction, the battery board must be replaced to preserve the integrity of the instruments.
The battery board is so called because it contains 2 small batteries used to maintain memory of the service indicator lights when the main battery is disconnected.
From 6/89 production, the boards were redesigned to use Lithium rather than NiCad batteries, and also the circuitry was changed so that the Lithium batteries were drawn on only when the main battery was disconnected. Prior to this, the NiCad batteries supplied power to the service indicator board at all times , and were recharged during vehicle operation.
Replacement of these batteries will often suffice to repair associated problems, however, a thorough check of the battery board is required to ensure there are no cracked solder joints. Re-flowing any suspect joints should also be done at the same time as replacing the batteries.

E30 M3 Repair Manual V2.7. Copyright ©1999-2001 Koala Motorsport & Brett Anderson