Coolant Temperature Switch

1. Connect voltmeter between terminals 2 and 6 on idle control unit plug. With ignition on, 0 VDC should be present with coolant temperature of 30°C (86°F) or less.

2. If voltage is incorrect, check resistance between white wire plug connection and ground. Resistance should be:
Coolant temperature at 30°C (86°F) or less at least 100K Ohms
Coolant temp at 48°C (118°F) and above 0 Ohms
a. If resistance is not within specification, replace temp. sensor.
b. If resistance is within specification, check connections for tight fit and good contact.

3. Connect voltmeter between terminals 2 and 6 on idle control unit plug. With ignition on, battery voltage should be present with coolant temperature of 48°C (118°F) or higher.

4. If voltage values are incorrect check:
a. White wire of temperature sensor for breaks, and repair as necessary.
b. Contact pins of temperature sensor for tight fit and good contact.
c. 'Warm' temperature sensor resistance.