Instrument Cluster

Insturment Cluster


There seems to be a lot of confusion in the archives between the Instrument Voltage Regulator (IVR) and the Anti Slosh circuit board. Other possible causes of gauges reading bad are wiring faults and faulty sending units.

The IVR is a TO-220 case transistor mounted inside the back of the fuel and temp gauge. It is rated at +10V output, and can be easily tested by checking the voltage on the RED wire going to the Anti Slosh board. The recommended procedure in the shop manual is to disconnect the fuel level sender (fuel gauge nut shown above) and check for +10V at the sender connector. The sender is a variable resistor that reads a high (full) of 19 ohms and low (empty) of 250 ohms. A bad IVR will cause BOTH the fuel and water temp to read abnormal (usually low). A bad Coolant temp sender will cause only the coolant gauge to read low. The coolant sender also has a resistance of 19 to 250 ohms. The IVR is inside the Instrument cluster, inside the fuel/temp gauge and cannot be seen without taking the cluster apart. The IVR will be difficult to replace because of its location and the way its soldered to the fuel/temp gauge. The Ford recommended fix is to replace the fuel/temp gauge assembly from the instrument cluster. A replacement +10V regulator can be substituted for the factory part, but it must be a high current regulator. The gauge draws about 500mA at full tank, and full hot. Texas Instruments does offer a +10V 1.2Amp regulator, that should work. (It's a 7810, NOT a 78L10 or a 78M10, those have less current capability) I'd bet Radio Shack can get it,for you, if you order it. It's no fun to change though.

A faulty Anti Slosh board will cause the fuel gauge read inaccurately but will not affect the coolant level reading. The Anti Slosh board consists of two transistors and an opamp. What this circuit does is dampen the movement of the gauge to compensate for sudden changes in the fuel tank level from braking, cornering etc. The Anti Slosh board can be removed from the back of the instrument cluster, and the fuel gauge will still work. You will not hurt anything by doing this and you can verify whether the Anti Slosh board is defective by doing so. Remember the orientation of the YELLOW and GREEN wires and be sure to replace the nylon insulator separating the two wires. The insulator is not necessary with the Anti Slosh board removed.The Anti Slosh board is the PC board velcro'd to the back of the instrument cluster. It has 4 wires connecting it to the instrument cluster. The colors are:

Red: +10V input from the IVR
Green: Input to the Anti Slosh board comes from the fuel level sender
Yellow: Output of the Anti Slosh board that drives the fuel gauge
Black: Ground


To remove the tach
remove the 3 nuts and spring washers and carefully remove tach assy

To remove the speedo
remove the 2 screws and carefully remove the speedo assy

To remove the temperature / fuel gauge assy
remove the 4 nuts and spring washers and carefully remove, there is a clear plastic "ear" under both the speedo and the tach. If caution is used the temp/fuel gauge assy can be removed without removing the other 2 gauges