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Inspection Procedure 6: Driver's door lock/unlock switch does not work.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the outside transmission antenna assembly (driver's side)
  • Malfunction of the lock/unlock switch (driver's side)
  • Damaged wiring harness and connectors
  • Malfunction of the KOS-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code.
Check if any DTC is set in the KOS-ECU.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the power supply mode of the electric motor switch to the OFF before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect scan tool (M.U.T.-IIISE) ."
(2) Turn the power supply mode of the electric motor switch to ON.
(3) Check if DTC is set.
(4) Turn the power supply mode of the electric motor switch to OFF.
Is the DTC set?
Refer to diagnostic trouble code chart .
Go to Step 2.
 
STEP 2. Lock/unlock switch (driver’s side) check
Check that the lock/unlock switch (driver’s side) is normal (Refer to GROUP 42A, Door - Door Handle and Latch ).
Is the check result normal?
Go to Step 3.
Replace the lock/unlock switch (driver’s side).
 
STEP 3. Resistance measurement at lock/unlock switch (driver’s side) connector (ground line)
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the lock/unlock switch (driver’s side) connector (ground line) and body ground.
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 5.
Go to Step 4.
 
STEP 4. Check of open circuit in ground line between the lock/unlock switch (driver’s side) connector and the body ground.
noteBefore the wiring harness check, check the intermediate connectors, and repair if necessary.
Is the check result normal?
Go to Step 6.
Repair the wiring harness.
 
STEP 5. Check of short to power supply, short to ground, and open circuit in DRRQ line between the KOS-ECU connector and the lock/unlock switch (driver’s side) connector.
noteBefore the wiring harness check, check the intermediate connectors, and repair if necessary.
Is the check result normal?
Go to Step 6.
Repair the wiring harness.
 
STEP 6. KOS communication test
Using scan tool (M.U.T.-IIISE), perform the antenna communication test to check that the outside transmission antenna assembly (driver's side) communicates normally (Refer to ).
Is the check result normal?
Go to Step 7.
Perform troubleshooting for the diagnostic trouble code No. B240A (Refer to ).
 
STEP 7. Check of the troubles
Operate the lock/unlock switch (driver’s side) and check that the doors can be locked and unlocked.
Is the check result normal?
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Deal with Intermittent Malfunction ).
Replace KOS-ECU and register the ID codes (Refer to ).