speedometer works, but the the the tachometer, fuel guage, battery and temp dont

Symptom: Fuel and temperature gauges are both inoperative or inaccurate. System: Body/Chassis Electrical Problem: The voltage stabilizer in the instrument cluster malfunctions. Test & Fix: Test the wires at the sensors for voltage. The reference voltage from the cluster, with ignition on, should be 10 volts. If it is more than 0.25 volts higher or lower, the voltage stabilizer attached to the rear of the instrument cluster should be tested for battery voltage and ground inputs and a steady 10 volts output. If power and ground are good, and the output is incorrect, replace the voltage stabilizer.