Manufacturer Code Charts: 31

31-EVAPORATOR SENSOR OPEN (MTC)





For a complete wiring diagram Refer to Diagrams/Electrical.

- When Monitored:

With the ignition on.

- Set Condition:

If the Evaporator Temperature Sensor input is out of range toward the high voltage threshold.





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 (MTC) for stored DTC test procedures. HVAC System Test (MTC)

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 C2 harness connector.

Turn the ignition on.

Measure the voltage of the (C21) Evaporator Temperature Sensor Signal circuit.

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, & EVAPORATOR TEMPERATURE SENSOR





Turn the ignition off.

Measure the resistance between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the A/C Heater Control C2 harness connector. The approximate circuit resistance should be as follows:
- 1468 ohms @ 40° C (104° F)
- 1800 ohms @ 35° C (95° F)
- 2221 ohms @ 30° C (86° F)
- 2757 ohms @ 25° C (77° F)
- 3443 ohms @ 20° C (68° F)
- 4330 ohms @ 15° C (59° F)
- 5485 ohms @ 10° C (50° F)
- 6998 ohms @ 5° C (41° F)
- 7354 ohms @ 4° C (39° F)
- 7731 ohms @ 3° C (37° F)
- 8130 ohms @ 2° C (36° F)
- 8553 ohms @ 1° C (34° F)
- 9000 ohms @ 0° C (32° F)

Is the resistance within the specifications?

Yes

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 3

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





Disconnect the Evaporator Temperature Sensor 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 C2 harness connector.

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 C2 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Replace the Evaporator Temperature Sensor.
- 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