B2451
DTC B2451 UNLATCH & CINCH MOTOR SHORT LOWComponent Location:
GENERAL DESCRIPTION
Power tailgate (hereinafter PTG) is the system which moves tailgate of vehicle by electronic motor so that user can open or close door with less force than required on manual operation. Latch assembly is adapted to control open/close tailgate, Latch assembly consists of latch motor and cinch motor and is located at tailgate. PTG ECU monitors position of forkbolt/detent switch and operates latch/cinch motor if necessary.
DTC DESCRIPTION
The ECM sets DTC B2451 if there's short in unlatch motor power harness.
DTC Detecting Condition:
Schematic Diagram:
MONITOR SCANTOOL DATA
1. Connect scantool to Data Link Connector (DLC).
2. Ignition "ON" & engine "OFF" & PTG "ON" & Latch switch "ON"
3. Monitor the "Unlatch Return Feedback" and "Unlatch Feedback" Parameter on the Scantool.
Specification: 1-9 V
4. Is the measured current data within specifications?
YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Go to "Inspection & Repair" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification Vehicle Repair" procedure.
NO - Go to "W/Harness Inspection" procedure.
POWER CIRCUIT INSPECTION
1. Check for short in harness
1. Ignition "OFF" & engine "OFF"
2. Disconnect "LATCH & CINCH #2" and "PTG module
3. Measure resistance between power terminal for unlatch motor of PTG module and unlatch motor.
Specification : Approx. Infinite ohm
4. Is the measured resistance within specifications?
YES - Go to "Ground circuit Inspection" procedure.
NO - Check for short in power harness. Repair as necessary and go to "Verification of Vehicle Repair procedure.
2. Check for short in harness
1. Ignition "OFF" & engine "OFF"
2. Disconnect "LATCH & CINCH #2" and "PTG module.
3. Measure resistance between return terminal for unlatch motor of PTG module and unlatch motor.
Specification: Approx. Infinite ohm
4. Is the measured resistance within specifications?
YES - Go to "Component Inspection" procedure.
NO - Check for short in harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Check latch switch
1. Ignition "ON" & engine "OFF"
2. Disconnect latch switch
3. Connect (+)terminal of battery to terminal 1 of latch switch and (-) terminal to terminal 2 of latch switch
4. Connect (+) terminal of battery to terminal 2 of latch switch and (-) terminal to terminal 1 of latch switch
Specification : Approx. "ON" -> 500 ohms, "OFF" -> 6.2 kohms ± 5%
5. Dose the latch motor work properly?
YES - Check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "PTG module inspection" procedure.
NO - Substitute with a known-good drive unit and check for proper operation. If the problem is corrected, replace latch switch and then go to "Verification of Vehicle Repair" procedure.
2. Check the "PTG module"
1. Ignition "ON" & engine "OFF"
2. Disconnect LATCH & CINCH #2 connector.
3. Measure the voltage between power terminal for UNLATCH MOTOR of PTG module and chassis ground.
Specification: Approx. 9-16 V
4. Is the measured voltage within specifications?
YES - Check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Substitute with a known-good "PTG module" and check for proper operation. If the problem is corrected, replace "PTG module" and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode and then clear DTC.
2. Operate the vehicle and monitor the DTC on the scantool.
3. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.