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Pinpoint Test AE: DTC B272B




Seats

Pinpoint Tests

Pinpoint Test AE: 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. 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 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 AE: DTC B272B

NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.

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AE1 CHECK THE PASSENGER BACKREST BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER

- Check the passenger 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 AE2.

No
REMOVE the obstruction or CLEAN the filter. CLEAR the DTCs. TEST the system for normal operation.

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AE2 CHECK OPERATION OF THE PASSENGER 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 passenger seat in high heat or high cool and monitor the seat operation. If a circuit fault is present, the DCSM disables the seat.
- Monitor the passenger 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 more than the cushion temperature, GO to AE3.

If the seat does not operate, GO to AE4.

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AE3 CHECK THE PASSENGER BACKREST TED FOR CORRECT INSTALLATION AND FOR A CRUSHED CLIMATE CONTROLLED SEAT MANIFOLD

- Remove the seat backrest cover. Refer to Seat Backrest - Front, Bucket Seat Bucket Seat.
- Check the passenger backrest TED and climate controlled seat manifold for damage, restriction and for correct installation.
- Is the passenger backrest TED correctly installed and the climate controlled seat manifold OK?

Yes
INSTALL a new passenger backrest TED. REFER to Seat Backrest - Front, Bucket Seat Bucket Seat. CLEAR the DTCs. TEST the system for normal operation.

No
Correctly INSTALL the passenger backrest TED or INSTALL a new climate controlled seat manifold. CLEAR the DTCs. TEST the system for normal operation.

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AE4 CHECK THE PASSENGER BACKREST TED THERMISTOR CIRCUIT FOR A SHORT TO GROUND

NOTE: If a seat equipped with a seat mounted side air bag is being serviced, 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.

- Ignition OFF.

- WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.

- For vehicles equipped with seat side air bags, carry out the following:
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect the passenger seat side air bag module C339.
- Connect the battery ground cable. Refer to Battery, Mounting and Cables Battery Disconnect / Connect.
- Disconnect: DCSM C3265B.
- Disconnect: Passenger 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 AE5.

No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

For vehicles equipped with seat side air bags, 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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AE5 CHECK THE PASSENGER BACKREST 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 AE6.

No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.

For vehicles equipped with seat side air bags, 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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AE6 CHECK THE BLOWER CIRCUITS FOR AN OPEN

- Measure the resistance between:
- DCSM C3265C-8, circuit CHS08 (BN/YE), harness side and passenger backrest TED C3039-2, circuit CHS03 (GN/BN), harness side.
- DCSM C3265C-7, circuit RHS08 (VT/WH), harness side and passenger backrest TED C3039-4, circuit RHS03 (GY/OG), harness side.
- DCSM C3265C-4, circuit VHS21 (BU/WH), harness side and passenger backrest TED C3039-7, circuit VHS16 (BU/GN), harness side.




- Are the resistances less than 5 ohms?

Yes
INSTALL a new passenger backrest TED. REFER to Seat Backrest - Front, Bucket Seat Bucket Seat. CLEAR the DTCs. TEST the system for normal operation.

For vehicles equipped with seat side air bags, 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.

For vehicles equipped with seat side air bags, 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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