B1237

DTC Troubleshooting: B1237 (N and AUTO)

DTC B1237 or DTC indicator N and AUTO:

A Short in the Passenger's Air Mix Control Motor Circuit

1. Clear the DTC with the HDS.

2. Turn the ignition switch to LOCK (0), and then back to ON (II), or press the engine start/stop button to select the OFF mode, and then the ON mode.

3. Do the Self-Diagnostic Function with the HDS or the climate control unit.

4. Check for DTCs.

Is DTC B1237 or N and AUTO indicated?

YES -

Go to step 5.

NO -

Intermittent failure. Check for loose or poor connection on the passenger's air mix control motor circuit.

5. Check for DTCs.

Are these DTCs also present; B1234 or K and AUTO, and/or B2968 or B and WINDSHIELD DEFROST, and/or B2980 or F and WINDSHIELD DEFROST?

YES -

Go to step 13.

NO -

Go to step 6.

6. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

7. Test the passenger's air mix control motor Passenger's Air Mix Control Motor Test.

Is the passenger's air mix control motor OK?

YES -

Go to step 8.

NO -

Replace the passenger's air mix control motor Passenger's Air Mix Control Motor Replacement.

8. Disconnect the passenger's air mix control motor 7P connector.

9. Disconnect climate control unit connectors A (32P) and C (20P).

10. Check for continuity between climate control unit connector A (32P) terminal No. 26 and body ground.





Is there continuity?

YES -

Repair a short to body ground in the wire between the climate control unit and the passenger's air mix control motor.

NO -

Go to step 11.

11. Check for continuity between climate control unit connector A (32P) terminal No. 26 and climate control unit connector C (20P) terminal No. 2.





Is there continuity?

YES -

Repair a short in the wire between the climate control unit and the passenger's air mix control motor.

NO -

Go to step 12.

12. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode, and measure the voltage between climate control unit connector A (32P) terminal No. 26 and body ground.





Is there any voltage?

YES -

Repair a short to power in the wire between the climate control unit and the passenger's air mix control motor. This short may also damage the climate control unit. Repair a short to power before replacing the climate control unit.

NO -

Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Service and Repair.

13. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode, and disconnect climate control unit connector C (20P).

14. Disconnect these items:

- Driver's air mix control motor
- Passenger's air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor

15. Check for continuity between climate control unit connector C (20P) terminal No. 2 and body ground.





Is there continuity?

YES -

Repair a short to body ground in the wire between the climate control unit and the passenger's air mix control motor.

NO -

Go to step 16.

16. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode, and measure the voltage between climate control unit connector C (20P) terminal No. 2 and body ground.





Is there any voltage?

YES -

Repair a short to power in the wire between the climate control unit and the passenger's air mix control motor. This short may have also damaged the climate control unit. Repair a short to power before replacing the climate control unit.

NO -

Go to step 17.

17. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

18. Reconnect climate control unit connector C (20P).

19. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode, and measure the voltage between climate control unit connector C (20P) terminal No. 2 and body ground.





Is there about 5 V?

YES -

Go to step 20.

NO -

Check for loose wires or poor connections at climate control unit connector C (20P). If the connection is good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Service and Repair.

20. While measuring the voltage between climate control unit connector C (20P) terminal No. 2 and body ground, reconnect these items individually and note the voltage reading each time:

- Driver's air mix control motor
- Passenger's air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor





Does the voltage remain at about 5 V?

YES -

Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Service and Repair.

NO -

Replace the component that caused the voltage drop.