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DTC B1124: A/M damper circuit open
DTC B1127: A/M damper circuit short
 
 
 
 
DTC SET CONDITION
  • When the air conditioning outlet temperature cannot be adjusted, open circuit (DTC B1124) and short circuit (DTC B1127) of the air mixing damper control motor circuit are set. <Single-zone AUTO A/C>
  • When the air conditioning outlet temperature on the driver's seat side cannot be adjusted, open circuit (DTC B1124) and short circuit (DTC B1127) of the air mixing damper control motor (Driver's side) circuit are set. <Dual-zone AUTO A/C>
 
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the air mixing damper control motor <Single-zone AUTO A/C>
  • Malfunction of the air mixing damper control motor (Driver's side) <Dual-zone AUTO A/C>
  • Malfunction of the upper case assembly [integrated air mixing damper <Single-zone AUTO A/C> or the air mixing damper (Driver's side) <Dual-zone AUTO A/C>]
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
  • Malfunction of the A/C controller assembly (A/C-ECU)
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the compressor operation.
Check that the compressor operates under the following conditions.
  • Engine operation
  • Air volume control dial: Maximum
  • Air conditioning switch: ON
  • Temperature control dial: MAX COOL
Is the check result normal?
Go to Step 2.
Refer to inspection procedure 5 "The A/C compressor does not work" .
 
STEP 2. Using scan tool (M.U.T.-IIISE), check actuator test.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Carry out the actuator test (Refer to ).
Item No.4: Driver's side air mixing damper
Is the check result normal?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check of open circuit in IG1, DA, DA', DB and DB' line between air mixing damper control motor <Single-zone AUTO A/C> or air mixing damper control motor (Driver's side) <Dual-zone AUTO A/C> connector and A/C controller assembly (A/C-ECU) connector.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Check the operation of the air mixing damper <Single-zone AUTO A/C> or the air mixing damper (Driver's side) <Dual-zone AUTO A/C>.
(1) Remove the air mixing damper control motor <Single-zone AUTO A/C> or the air mixing damper control motor (Driver's side) <Dual-zone AUTO A/C>.
(2) Insert an hexagonal wrench to the axis of the air mixing damper <Single-zone AUTO A/C> or the air mixing damper (Driver's side) <Dual-zone AUTO A/C> and turn it by hand to check whether the air mixing damper <Single-zone AUTO A/C> or the air mixing damper (Driver's side) <Dual-zone AUTO A/C> works normally.
OK: The air mixing damper <Single-zone AUTO A/C> or the air mixing damper (Driver's side) <Dual-zone AUTO A/C> turns smoothly without tight spots within the range of approximately 80 degrees.
Is the check result normal?
Go to Step 5.
Replace the upper case assembly.
 
STEP 5. Check whether the DTC is set again.
Is the DTC set?
Replace the air mixing damper control motor. Then go to Step 6.
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 6. Check whether the DTC is set again.
Is the DTC set?
Replace the A/C controller assembly (A/C-ECU).
This procedure is complete.