1989 944S2 race car with 968 motor.

When I got the car, the factory gas gauge was pegged at full. When I unplugged the wires from the sending unit, the gauge went to empty. We assumed that the sending unit was therefore at fault. I didn't originally notice it, but the brake lining light, next to the gas gauge goes on when the sender is disconnected.

Bought new sending unit and installed it. The gas gauge still shows full when connected and empty when disconnected. The brake lining light lights up only when the sender is disconnected. FWIW, I don't have the brake lining warning sensors connected because race car😉

Since this is a race car, I'm not interested in buying a new cluster, but I'm guessing the plastic circuit board on the back of the cluster has a short. I'm thinking of installing a VDO gas gauge with the correct resistance and forgetting about the cluster issue.

Anyone with a similar problem, suggestions, or advice on installing the VDO gauge, please advise!

 

Are the wires going to the brake sensors wired together? Twisting the ends together and soldering them, covered with shrink tubing will fool the system and the light will be disabled.

 

The question is why isn't the brake lining light on all the time? It only goes on when the fuel level sender wires are disconnected.

Going to try pulling the cluster and checking the circuits on the back.

 

Solved the problem by adding a VDO fuel gauge. I didn't want to buy a new cluster, so I thought this was the better option. The VDO gauge required three wires: 12V switched, ground and signal wire. That happens to be the solid green wire from the sender. I sliced open the wire harness that runs across the front of the trunk area. I fished out the green wire, extended it to the gauge and voila! I now know I have a quarter tank of bad gas!