B1041

DTC B1041, B1042: Air Mixing Damper Control Motor And Potentiometer (Potentiometer System)

Air Mixing Damper Control Motor Potentiometer Circuit:

DTC SET CONDITION
- DTC B1041 or B1042 is set if there is an open or short circuit in the potentiometer input circuit, or if there is an open circuit in the power circuit or ground circuit.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble
- The A/C-ECU, the air mixing damper control motor and potentiometer, or connector(s) or wiring between the two may be defective.

Past trouble
- If DTC B1041 or B1042 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) between the A/C-ECU and the air mixing damper control motor and potentiometer. If the connectors and wiring are normal, and obviously the ECU is the cause of the trouble, replace the ECU. If in doubt, do not replace the ECU.

TROUBLESHOOTING HINT
- Malfunction of connector.
- Malfunction of the harness.
- Malfunction of the air mixing damper control motor and potentiometer.
- Malfunction of the A/C-ECU.

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

Use scan tool MB991958 to diagnose the CAN bus lines.







1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Diagnose the CAN bus line.

Q: Is the check result satisfactory?

YES : Go to Step 2.

NO : Repair the CAN bus lines. Then go to Step 7.

STEP 2. Recheck for diagnostic trouble code.

Recheck if the DTC is set.

1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.

Q: Is the check result satisfactory?

YES : It can be assumed that this malfunction is intermittent.

NO : Go to Step 3.

STEP 3. Using scan tool MB991958, check data list.







CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958 to the data link connector.
2. Start the engine.
3. Set scan tool MB991958 to the data reading mode.
- Item 10: air mix potentiometer.
- Check that the set position of the heater control matches the displayed position on the scan tool.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor within the specified range?

YES : Replace the A/C-ECU. Then go to Step 7.

NO : Go to Step 4.

STEP 4. Check A/C-ECU connectors C-15, C-16 and air mixing damper control motor and potentiometer connector C-105 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Are A/C-ECU connectors C-15, C-16 and air mixing damper control motor and potentiometer connector C-105 in good condition?

YES : Go to Step 5.

NO : Repair or replace the connector. Then go to Step 7.

STEP 5. Check the wiring harness between A/C-ECU connectors C-15 (terminals 16 and 20), C-16 (terminal 29) and air mixing damper control motor and potentiometer connector C-105 (terminals 5, 7 and 3).










NOTE: Also check joint connector C-03 for loose, corroded, or damaged terminals, or terminals pushed back in the connector If joint connector C-03 is damaged, repair or replace the connector.

- Check the A/C-ECU signal line for open and short circuit.

Q: Are the wiring harness between A/C-ECU connectors C-15 (terminals 16 and 20), C-16 (terminal 29) and air mixing damper control motor and potentiometer connector C-105 (terminals 5, 7 and 3) in good condition?

YES : Go to Step 6.

NO : Repair the wiring harness. Then go to Step 7.

STEP 6. Check the air mixing damper control motor and potentiometer.

CAUTION: Do not apply battery voltage when the damper is in the MAX COOL or MAX HOT position.







1. Operate the air mixing damper control motor as described in the table below.







2. Measure the resistances between connector terminals 3 and 5, and between 3 and 7, while the air mixing damper control motor is running. The resistances should change gradually within the standard value.

Standard value: 1.7 (MAX HOT) -5.0 (MAX COOL) kohms

Q: Are the air mixing damper control motor and potentiometer in good condition?

YES : Repair the A/C-ECU. Go to Step 7.

NO : Replace the air mixing damper control motor and potentiometer. Then go to Step 7.

STEP 7. Recheck for diagnostic trouble code.







Check again if the DTC is set.

1. Connect scan tool MB991958 to the data link connector
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result satisfactory?

YES : The procedure is complete.

NO : Return to Step 1.