Pinpoint Test AO: DTC B272B
Seats
Pinpoint Tests
Pinpoint Test AO: DTC B272B
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
The Dual Climate Controlled Seat Module (DCSM) monitors seat backrest temperature on circuit VHS36 (YE/BU). The DCSM supplies voltage to both blowers on circuit CHS03 (BN/GN), ground to both blowers on circuit RHS03 (GY/OG) and supplies a variable voltage to circuit VHS16 (BU/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 B272B (Passenger Back Over-Temp Detected) - If the passenger seat backrest TED temperature exceeds 85°C (185°F) in cool mode or 70°C (158°F) in heat mode for more than 34 seconds the DCSM will shut down the passenger seat system and set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Restricted backrest TED filter
- Crushed or restricted climate controlled seat manifold
- Backrest TED assembly
PINPOINT TEST AO: DTC B272B
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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AO1 CHECK THE BACKREST 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 AO2.
No
REMOVE the obstruction or CLEAN the filter. CLEAR the DTCs. TEST the system for normal operation.
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AO2 CHECK OPERATION OF THE SEAT AND MONITOR SEAT TEMPERATURE USING THE SCAN TOOL
- Enter the following diagnostic mode on the scan tool: DataLogger - DCSM.
- Passenger Cushion Thermal Electric Device (TED) Temperature (PCSHTMP)
- Passenger Back TED Temperature (PBKTMP)
- 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. CLEAR the DTCs. TEST the system for normal operation.
No
If the seat is operational, but the backrest temperature increases greater than the cushion, GO to AO3.
If the seat does not operate, GO to AO4.
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AO3 CHECK THE TED FOR CORRECT INSTALLATION AND FOR A CRUSHED CLIMATE CONTROLLED SEAT MANIFOLD
- Remove the seat backrest cover. Refer to Seat Backrest Cover - Front Seat Backrest 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 backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. CLEAR the DTCs. TEST the system for normal operation.
No
CORRECTLY install the backrest TED or INSTALL a new climate controlled seat manifold. CLEAR the DTCs. TEST the system for normal operation.
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AO4 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: Passenger Seat Side Air Bag Module C339.
- Disconnect: DCSM C3265B.
- Disconnect: Backrest TED C3039.
- Measure the resistance between DCSM C3265B-4, circuit VHS36 (YE/BU), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AO5.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C339. REPOWER the SRS. REFER to Restraint Systems.
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AO5 CHECK THE TED THERMISTOR CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between DCSM C3265B-4, circuit VHS36 (YE/BU), harness side and DCSM C3265B-5, circuit RHS20 (GN/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AO6.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C339. REPOWER the SRS. REFER to Restraint Systems.
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AO6 CHECK THE BLOWER CIRCUITS FOR AN OPEN
- Measure the resistance between:
- DCSM C3265C-8, circuit CHS08 (BN/YE), harness side and backrest TED C3039-2, circuit CHS03 (GN/BN), harness side.
- DCSM C3265C-7, circuit RHS08 (VT/WH), harness side and backrest TED C3039-4, circuit RHS03 (GY/OG), harness side.
- DCSM C3265C-4, circuit VHS21 (BU/WH), harness side and backrest TED C3039-7, circuit VHS16 (BU/GN), harness side.
- Are the resistances less than 5 ohms?
Yes
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. CLEAR the DTCs. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C339. REPOWER the SRS. REFER to Restraint Systems.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C339. REPOWER the SRS. REFER to Restraint Systems.
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