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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
STEP 1. Using scan tool MB991958, read the diagnostic trouble code.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the power supply mode of the engine switch to the OFF position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to "How to connect scan too (M.U.T.-III) ."
(2) Turn the power supply mode of the engine switch to ON.
(3) Check whether the KOS-ECU related DTC is set.
(4) Turn the power supply mode of the engine switch to OFF.
Is the DTC set?
Diagnose the KOS-ECU. Refer to diagnostic trouble code chart .
Go to Step 2.
 
STEP 2. Check KOS-ECU connector C-10 and lock/unlock switch (front door: LH) connector F-15 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Are KOS-ECU connector C-10 and lock/unlock switch (front door: LH) connector F-15 in good condition?
Go to Step 3.
Repair or replace the damaged component(s). Refer to GROUP 00E, Harness Connector Inspection . Check that the driver’s door lock/unlock switch works normally.
 
STEP 3. Check the lock/unlock switch (driver’s side).
(1) Remove the door outside handle base. Refer to GROUP 42A, Door Handle and Latch .
(2) Check continuity when the lock/unlock switch (driver’s side) is operated to "ON" or "OFF" position.
 
Switch positionTerminal numberSpecified condition
ON1 - 2Continuity exists (2 Ω or less)
OFF1 - 2Open circuit
Is the lock/unlock switch (driver’s side) normal?
Go to Step 4.
Replace the door outside handle base (driver’s side).
 
STEP 4. Check the wiring harness between KOS-ECU connector C-10 (terminal No. 16) and lock/unlock switch (front door: LH) connector F-15 (terminal No. 1), and between lock/unlock switch (front door: LH) connector F-15 (terminal No. 2) and ground.
  • Check the signal and ground wires for open circuit.
noteAlso check intermediate connectors C-224, C-225 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connectors C-224, C-225 is damaged, repair or replace the damaged component(s) as described in GROUP 00E, Harness Connector Inspection .
Are the wiring harness between KOS-ECU connector C-10 (terminal No. 21) and lock/unlock switch (front door: LH) connector F-15 (terminal No. 1), and between lock/unlock switch (front door: LH) connector F-15 (terminal No. 2) and ground in good condition?
Go to Step 5.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Check that the driver’s door lock/unlock switch works normally.
 
STEP 5. KOS communication test
Using scan tool (M.U.T-III), 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 6.
Perform troubleshooting for the DTC B240A (Refer to ).
 
STEP 6. Check of the troubles
Operate the lock/unlock switch (front door: LH) and check that the door can be locked.
Is the check result normal?
The diagnosis is complete.
Replace KOS-ECU and register the ID codes (Refer to ).