Pinpoint Test AL: DTC B2729
Seats
Pinpoint Tests
Pinpoint Test AL: DTC B2729
Refer to Wiring Diagram Set 119 (Fusion/Milan/MKZ, Fusion Hybrid/Milan Hybrid), Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
The Dual Climate Controlled Seat Module (DCSM) monitors the seat cushion temperature on circuit VHS26 (VT). The DCSM supplies voltage to both blowers on circuit CHS03 (GN/BN), ground to both blowers on circuit RHS03 (GY/OG) and supplies a variable voltage to circuit VHS18 (BN/GN) to control the blower speed. Cabin air enters the blower through a filter attached to the Thermo-Electric Device (TED) housing. Conditioned air exits the TED and flows through a manifold attached to the foam pad.
- DTC B2729 (Cushion Over-Temp Detected) - In the heating mode, if the driver seat cushion TED temperature exceeds 85°C (185°F) for more than 34 seconds, the TED is disconnected or the duct is blocked, the DCSM will shut down the driver seat system and set this DTC.
- DTC B2729 (Cushion Over-Temp Detected) - In the cooling mode, if the driver seat cushion TED temperature exceeds 70°C (158°F) for more than 34 seconds, the TED is disconnected or the duct is blocked, the DCSM will shut down the driver seat system and set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Restricted cushion TED filter
- Crushed or restricted climate controlled seat manifold
- Cushion TED assembly
PINPOINT TEST AL: DTC B2729
NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition is ON.
NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
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AL1 CHECK THE CUSHION BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER
- Check the seat for any obstruction at the TED assembly and for a restricted filter.
- Is the filter clean and blower clear of any obstruction?
Yes
GO to AL2.
No
REMOVE the obstruction or INSTALL a new filter. REPEAT the self-test. CLEAR the DTCs. TEST the system for normal operation.
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AL2 CHECK OPERATION OF THE SEAT AND MONITOR SEAT TEMPERATURE USING THE SCAN TOOL
- Enter the following diagnostic mode on the scan tool: DataLogger - DCSM - PIDs .
- Seat cushion thermal electric device temperature (CSHTEMP)
- Seat back thermal electric device temperature (BK_TEMP)
- Start the engine.
- Operate the seat in high heat or high cool and monitor the seat operation. If a circuit fault is present, the DCSM will disable the seat.
- Monitor the cushion and backrest temperature PIDs while the seat is operating. The temperatures should be similar during operation.
- Does the seat operate and temperature PIDs indicate correct operation?
Yes
The system is operating correctly at this time. The fault may have occurred from incorrectly switching between heat and cool modes. REPEAT the self-test. CLEAR the DTCs.
No
If the seat is operational, but the cushion temperature increases greater than the backrest, GO to AL3.
If the seat does not operate, GO to AL4.
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AL3 CHECK THE TED FOR CORRECT INSTALLATION AND FOR A CRUSHED CLIMATE CONTROLLED SEAT MANIFOLD
- Remove the seat cushion cover. Refer to Seat Cushion Cover - Front Seat Cushion Cover - Front.
- Check the TED and climate controlled seat manifold for damage, restriction and for correct installation.
- Is the TED correctly installed and the climate controlled seat manifold OK?
Yes
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs. TEST the system for normal operation.
No
CORRECTLY install the cushion TED or INSTALL a new climate controlled seat manifold. REPEAT the self-test. CLEAR the DTCs. TEST the system for normal operation.
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AL4 CHECK THE TED THERMISTOR CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the
General Procedures portion of Restraint Systems.
- Disconnect: Driver Seat Side Air Bag C327 .
- Disconnect: Passenger Seat Side Air Bag C313 .
- Disconnect: DCSM C3305B .
- Disconnect: Cushion TED C3300 .
- Measure the resistance between DCSM C3305B-7, circuit VHS26 (VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AL5.
No
REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327 and passenger seat side air bag module C313.
REPOWER the SRS. REFER to Restraint Systems.
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AL5 CHECK THE TED THERMISTOR CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between DCSM C3305B-7, circuit VHS26 (VT), harness side and DCSM C3305B-8, circuit RHS05 (YE/VT), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AL6.
No
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327 and passenger seat side air bag module C313.
REPOWER the SRS. REFER to Restraint Systems.
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AL6 CHECK THE BLOWER CIRCUITS FOR AN OPEN
- Measure the resistance between:
- DCSM C3305C-16, circuit CHS03 (GN/BN), harness side and cushion TED C3300-2, circuit CHS03 (GN/BN), harness side.
- DCSM C3305C-15, circuit RHS03 (GY/OG), harness side and cushion TED C3300-4, circuit RHS03 (GY/OG), harness side.
- DCSM C3305C-11, circuit VHS18 (BN/GN), harness side and cushion TED C3300-7, circuit VHS18 (BN/GN), harness side.
- Are the resistances less than 5 ohms?
Yes
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327 and passenger seat side air bag module C313.
REPOWER the SRS. REFER to Restraint Systems.
No
REPAIR the circuit(s). TEST the system for normal operation. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327 and passenger seat side air bag module C313.
REPOWER the SRS. REFER to Restraint Systems.
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