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:
at least 100K Ohms coolant temperature at 30°C (86°F) or less.
0 Ohms coolant temp at 48°C (118°F) and above.
a. If resistance is not within specification, replace temp. switch.
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 switch for breaks, and repair as necessary.
b. Contact pins of temperature switch for tight fit and good contact.
c. 'Warm' temperature switch resistance.