DTC 22

Code 22:

CIRCUIT DESCRIPTION:

The Coolant Temperature Sensor (CTS) uses a thermistor to control the signal voltage to the ECM. The ECM applies a voltage on wire to the sensor. When the engine is cold, the sensor (thermistor) resistance is high, therefore, ECM will see high signal voltage. As the engine warms, the sensor resistance becomes less, and the voltage drops. At normal engine operating temperature 80°C to 95°C (176°F to 203°F), the voltage will measure about 1.5 to 2.0 volts at the ECM.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Verifies that 4-5 volts is present at the CTS connector.

2. This test checks the ground side of the CTS circuit.

3. Determines if the problem is caused by an open BROWN wire or the ECM. Be sure to check the ECM connections for proper fit.

4. Determines if the circuit or ECM is the problem. Be sure to check the ECM connections for proper fit.

DIAGNOSTIC AIDS:

After engine is started the temperature should rise steadily to about 95°C (203°F) then stabilize when thermostat opens. A faulty connection, or an open in the WHITE wire or BROWN wire can result in a Code 22. Testing and Inspection