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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 while it supplies voltage and ground to both blower motors. The DCSM also supplies a variable voltage signal to control the blower speed. Cabin air enters the blower through a filter attached to the Thermo-Electric Device (TED) housing. Heated or cooled 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 shuts down the passenger seat system and sets 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

NOTICE: When taking measurements at Dual Climate Controlled Seat Module (DCSM) harness connectors, do not insert the electrical probes into the female connector pins. Inserting the probes into connector pins can cause intermittent or open electrical connections after reassembly resulting in Diagnostic Trouble Codes (DTCs) and system failure. Touching the tip of these connector pins is recommended instead.

NOTE: If a seat equipped with a seat mounted side air bag is being repaired, the Supplemental Restraint System (SRS) must be depowered. Refer to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

NOTE: The air bag warning lamp illuminates when the Restraints Control Module (RCM) fuse is removed and the ignition switch is ON. This is normal operation and does not indicate an SRS fault.

NOTE: The 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 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 Supplemental Restraint System (SRS) Depowering and Repowering.
- 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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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AO6 CHECK THE BLOWER CIRCUITS FOR AN OPEN

- Disconnect: DCSM C3265C.
- 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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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