Instrument Cluster / Carrier: Description and Operation

The engine coolant temperature (ECT) gauge and the fuel gauge are each operated by two intersecting coils wound around a permanent magnet rotor. When voltage from fuse 23 is applied to the coils, a magnetic field is generated. This causes the rotor to rotate and the gauge needle to move. The magnetic field is controlled by the sender. As the resistance in the sender varies, current through the gauge coils changes. The gauge needle moves according to the changing magnetic field.

The engine coolant temperature (ECT) sending unit's resistance varies from approximately 142 ohms at low engine temperature to approximately 13 ohms at high engine temperature.

The fuel gauge sender's resistance varies from approximately 5 ohms at full to approximately 110 ohms at empty. Damping oil surrounding the fuel gauge keeps the gauge needle at the level last shown when the ignition was turned off.

With the engine running, the tachometer senses ignition pulses from the distributor through the ignition control module (ICM). The solid-state tachometer displays these pulses as engine speed. For each 200 pulses per minute from the ignition control module (ICM), the tachometer displays 100 rpm.