Cadillac Repair: 1989 Sadan Deville, purple wire, system fault

Question
QUESTION: The dash board is digital and the read out for the fuel just shows the letter d how can I get the system to show me how much gas is in the car. and is it very expensive to fix

ANSWER: Cathy,
That display indicates a system fault. Are there any trouble codes stored?

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QUESTION: No there are no codes just the letter d what does system fault mean, is it a fuse or need to be rewired can you break that down into a female terminology. LOL

Answer
Cathy,
Most likely the problem is a bad connection between the Fuel Data Panel and the BCM (Body Control Module). Check the purple wire on the back of the panel (circuit 719) should be terminal "V". Also check that it's connected to the BCM at terminal B1 on connector C1. If both connections appear good, check the circuit with a meter to make sure there's no break or short.
Sorry but that's about as "female" as it gets.