31-EVAPORATOR SENSOR OPEN (MTC)
For a complete wiring diagram Refer to Section 8W.
- When Monitored:
With the ignition on.
- Set Condition:
If the Evaporator Temperature Sensor input is out of range toward the high voltage threshold.
| 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 (MTC) for stored DTC test procedures.
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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 in accordance with the Service Information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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 in accordance with the Service Information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Repair the (C121) Sensor Ground circuit for an open.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).