Code No.B1090, B1091: Motor drive system for air mix damper

COMMENTS ON TROUBLE SYMPTOM
This code is set when the air mixing damper cannot be rotated to the preset opening angle.

PROBABLE CAUSE

  • Malfunction of the front air mixing damper control motor and potentiometer
  • Malfunction of the semi automatic air conditioner control panel (A/C-ECU)
  • Damaged wiring harness or connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test
Check that the actuator tests below can be performed correctly.

  • Item 43: Air mix dumper motor: 100%
  • Item 42: Air mix dumper motor: 0%

Q. Is the check result normal?
Go to Step 5.
Go to Step 2.

STEP 2. Connector check: B-113 A/C-ECU connector and B-12 air mixing damper control motor and potentiometer connector




Q. Is the check result normal?

Go to Step 3.

Repair the connector.

STEP 3. Check the wiring harness between B-113 A/C-ECU connector (terminals 13,15 and 12) and B-12 air mixing damper control motor and potentiometer connector (terminals 4,3 and 5) <LHD> or (terminals 1,5 and 4) <RHD>.





  • Check the motor activating lines for open and short circuit.

Q. Is the check result normal?

Go to Step 4.

Repair the wiring harness.

STEP 4. Check the air mixing damper control motor and potentiometer.
Refer to .

Q. Is the check result normal?
Go to Step 5.
Replace the air mixing damper control motor and potentiometer.

STEP 5. Check whether the diagnosis code is reset.

Q. Is the diagnosis code set?
Replace the semi automatic air conditioner control panel (A/C-ECU).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).