Coolant Temperature Gauge Sender Functional Check and Replacement

Before beginning this procedure, allow the engine to cool completely!
CHECK
PROCEDURE

1. The coolant temperature gauge system consists of a gauge mounted in the instrument cluster and a temperature sender mounted on the engine block, directly below the distributor (4-cylinder models) or mounted in the thermostat housing (V6 models). Some models may have more than one temperature sender; however, the gauge system uses only one of them.

The vehicles covered in this Manual are equipped with electric cooling and air conditioning fans. Keep your hands away from the fan blades, which may start unexpectedly with the ignition on, even when the engine is off.

2. If the gauge indicates overheating even when the engine is clearly cold, check the wiring between the instrument panel and the temperature sender for signs of a short circuit.
3. If the gauge does not function at all, check its electrical circuit by briefly grounding the wire leading to the temperature sender with the ignition on (do not start the engine). If the gauge needle moves to the end of the scale, replace the sender.

Keep your hands away from the cooling fan blades, which may start even when the engine is off!
4. If the needle remains stationary, check the gauge circuit wiring for an open circuit.
5. If you are not sure the temperature sender is serviceable, measure its electrical resistance with the engine cold and hot. Sender resistance should change inversely with temperature. With a cold engine (below 57°C), resistance should be about 137 ohms. As the engine warms up, resistance should gradually decrease and reach 30 to 46 ohms at 86 to 101 °C. Replace a faulty sender.

REPLACEMENT
PROCEDURE

To replace the temperature sender, unscrew it from the engine and quickly screw in the new one, with its threads lightly coated with sealant beforehand (do not use Teflon tape or PTFE thread tape to seal the sender).

The temperature sender must be replaced with the engine cold! Be prepared to catch spilled coolant. After replacing the sender, check the coolant level and top up if necessary (see Chapter Maintenance and Adjustments).