Diagnostic Aids

Perform this test only when directed by QUICK TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from IAT sensor. Engine coolant temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values may vary up to 15 percent due to sensor and VREF variations.

This circuit test is intended to diagnose the following components and circuits:

• Intake Air Temperature (IAT) sensor.
• Engine Coolant Temperature (ECT) sensor.
• Wiring harness circuits (IAT, ECT and SIG RTN).
• Powertrain Control Module (PCM).

To prevent replacing good components, ensure the following non-EEC areas or components are not cause of problem:

• Coolant level low.
• Cooling system, water pump or fan.
• Engine operating temperature.
• Engine oil level low.
• Thermostat.
• Air cleaner duct.
• Ambient temperature.