C1340
DTC C1340: Stoplight switchStoplight Switch Circuit
CAUTION: If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
CIRCUIT OPERATION
^ The "ON" signal when the brake pedal is pressed or the "OFF" signal when the brake pedal is released is input to the TCL/ASC-ECU (terminal 41.)
TCL/ASC DTC SET CONDITIONS
Diagnosis code No. 1340 is set in the following cases:
^ Stoplight switch is not operating properly and remains ON state and vehicle speed exceeds 12 mph (20 km/h) for more than 6 minutes.
^ Stoplight switch system harness is damaged and no signal is input to TCL/ASC-ECU.
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THESE DTCS ARE TO SET ARE:)
Current trouble
^ Malfunction of the stoplight switch
^ Incorrect positioning of stoplight switch
^ Damaged wiring harness or connector
^ Malfunction of the hydraulic unit (integrated with TCL/ASC-ECU)
PAST TROUBLE
Carry out diagnosis with particular emphasis on connector(s) or wiring harness between the TCL/ASC-ECU and the stoplight switch. For diagnosis procedures, refer to "How to cope with past trouble".
DIAGNOSIS
Required Special Tools:
^ MB991958: Scan Tool (M.U.T-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A
^ MB991997: ASC Check Harness
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
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) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES: Go to Step 3.
NO: Repair the CAN bus line. Then go to Step 2.
STEP 2. Recheck for diagnostic trouble code.
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) Turn the ignition switch to the "ON" position.
(2) Erase the DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Check if the DTC is set.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1340 set?
YES: Go to Step 3.
NO: The procedure is complete.
STEP 3. Check the stoplight operation.
Q: Does the stoplight come on and go out correctly?
YES: Then go to step 6.
NO: Go to Step 4.
STEP 4. Check the stoplight switch installation condition.
Q: Is the stoplight switch installed properly?
YES: Go to Step 5.
NO: Repair it and then go to Step 10.
STEP 5. Check the stoplight switch continuity.
(1) Remove the stoplight switch.
(2) Connect an ohmmeter to stoplight switch terminals 1 and 2, and check whether there is continuity when the plunger of the stoplight switch is pushed in and when it is released.
(3) The stoplight switch is in good condition if there is no continuity when the plunger is pushed in to a depth of within 4 mm (0.16 in) from the outer case edge surface, and if there is continuity when it is released.
Q: Is the check result normal?
YES: Check the stoplight circuit and repair and then go to Step 6.
NO: Replace the stoplight switch and then go to Step 10
STEP 6. Using scan tool MB991958, check data list items 6: Stoplight switch.
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) Turn the ignition switch to the "ON" position.
(2) Select "Interactive Diagnosis" from the start-up screen.
(3) Select "System Select."
(4) Choose "ABS/ASC/ASTC" from the "CHASSIS" tab.
(5) Select "Data List."
(6) Choose an item 06 and select the "OK" button.
^ Item 06: Stoplight switch
OK:
Brake pedal stepped down: ON
Brake pedal released: OFF
Q: Is the check result normal?
YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points -How to Cope with Intermittent Malfunction.
NO: Go to Step 7.
STEP 7. Measure the voltage at TCL/ASC-ECU connector A-38.
(1) Disconnect the connector A-38, and connect special tool MB991997 to the wiring harness-side connector.
NOTE: Do not connect special tool MB991997 to the TCL/ASC-ECU.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 41 and ground.
OK: Stoplight switch OFF: Less than 1V Stoplight switch ON (Depress the brake pedal): System voltage
Q: Is the check result normal?
YES: Erase the diagnosis code memory, and recheck if any diagnosis code sets. If diagnosis code No.C1340 set, replace the hydraulic unit (integrated with TCL/ASC-ECU). Then go to Step 10.
NO: Go to Step 8.
STEP 8. Check the harness wire between TCL/ASC-ECU connector A-38 terminal 41 and stoplight switch connector C-103 terminal 1.
NOTE: After inspecting TCL/ASC-ECU connector A-38, joint connectors C-28 and stoplight switch connector C-103, inspect the wire. If any of these connectors is damaged, repair or replace it. Then go to Step 10.
Q: Is the check result normal?
YES: Disconnect the connection between the combination meter and the engine-A/T-ECU or the engine-ECU, and then go to Step 9.
NO: Go to Step 10
STEP 9. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Check if the DTC is set.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1340 set?
YES: Replace the hydraulic unit (integrated with TCL/ASC-ECU). Then go to Step 10.
NO: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points How to Cope with Intermittent Malfunction.
STEP 10. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Drive the vehicle at 12 mph (20 km/h) or more for 6 minutes or more. (there is no need to drive continuously.)
(6) Stop the vehicle with braking at 25 mph (40 km/h) or more.
(7) Check if the DTC is set.
(8) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1340 set?
YES: Go to Step 1.
NO: The procedure is complete.