[Harley Eaton]

Your car is equipped with an Instrument Voltage Regulator, which controls (?) the voltage to the fuel, temp, and oil pressure gauge. The IVR must be grounded . If it is not, those gauges will read full scale (to the right). It could be that your IVR is bad. In that case, the gauge needles may not move from the left side of the gauge. The IVR is mounted on the right end of the speedometer by one screw. You may be able to replace it with one hand under the dash and the other hand through the hole with the clock removed.