Evaporator Temperature Sensor Circuit Open

EVAPORATOR TEMPERATURE SENSOR CIRCUIT OPEN

Evaporator Temperature Sensor Circuit Open:

WHEN MONITORED
With the ignition on.

SET CONDITION
If the A/C Heater Control senses voltage is greater than 4.9 volts on the (C21) Evaporator Temperature Sensor Signal circuit.

POSSIBLE CAUSES
- (C21) Evaporator temperature sensor signal circuit shorted to voltage
- (C21) Evaporator temperature sensor signal circuit open
- (C121) Sensor ground circuit open
- Evaporator temperature sensor
- A/C heater control

NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. Refer to HVAC System Test for stored DTC test procedures. HVAC System Test

Diagnostic Test

1. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE




Turn the ignition off.
Disconnect the A/C Heater Control C1 harness connector.
Turn the ignition on.
Measure the voltage of the (C21) Evaporator Temperature Sensor Signal circuit.

Q: Is the voltage above 0.2 volts?

YES: Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to voltage. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 2

2. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT & (C121) SENSOR GROUND CIRCUIT FUNCTION




Turn the ignition off.
Reconnect the A/C Heater Control C1 harness connector.
Disconnect the Evaporator Temperature Sensor harness connector.
Connect a jumper wire between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the Evaporator Temperature Sensor harness connector.
Turn the ignition on.
With the DRBIII(R) in Sensor Display, read the Evaporator Temperature Sensor voltage.

Q: Is the voltage below 0.10 volts?

YES: Replace the Evaporator Temperature Sensor. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 3

3. CHECK (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR AN OPEN




Turn the ignition off.
Remove the jumper wire from the Evaporator Temperature Sensor harness connector.
Disconnect the A/C Heater Control C1 harness connector.
Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between the Evaporator Temperature Sensor harness connector and the A/C Heater Control C1 harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go To 4
NO: Repair the (C21) Evaporator Temperature Sensor Signal circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

4. CHECK (C121) SENSOR GROUND CIRCUIT FOR AN OPEN




Measure the resistance of the (C121) Sensor Ground circuit between the Evaporator Temperature Sensor harness connector and the A/C Heater Control C1 harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Replace the A/C Heater Control. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Repair the (C121) Sensor Ground circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test