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Pinpoint Tests AR: DTC B272B




Seats

Pinpoint Test AR: 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 the temperature sensor. If the temperature exceeds the specified limits, the DTC will be set.

The presence of overtemperature faults (DTCs B2729, B2730, B272A and B272B) can be induced by incorrect operation of the climate controlled seat system after an initial heat setting has been attained. If a heat setting is repeatedly turned OFF and ON in an attempt to increase the seat temperature or repeatedly toggled between heat and cool modes, an overtemperature condition can result and the DTCs will be set.

- DTC B272B (Passenger Back Over-Temp Detected) - For heat mode, if the passenger seat backrest TED temperature exceeds 110°C (230°F) continuously for more than 4 seconds in any heat mode, the DCSM turns off the TED and enters a fan only state to recover from the over-temperature condition (recovery mode). If the TED temperature does not recover after 30 seconds, the DTC will set and the seat is disabled. If the TED does recover, the TED is re-enabled, the system continues to operate normally and the DTC will not be set. If the over-temperature condition occurs a second time within the same ignition cycle, the DTC will set and the seat is disabled.
- DTC B272B (Passenger Back Over-Temp Detected) - For cool mode, if the passenger seat backrest TED temperature exceeds 65°C (149°F) continuously for more than 4 seconds in any cool mode, the DCSM turns off the TED and enters a fan only state to recover from the over-temperature condition (recovery mode). If the TED temperature does not recover after 5 minutes, the DTC will set and the seat is disabled. If the TED does recover, the TED is re-enabled, the system continues to operate normally and the DTC will not be set. If the over-temperature condition occurs a second time within the same ignition cycle, the DTC will set and the seat is disabled.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Restricted backrest TED filter
- Crushed or restricted foam pad
- Backrest TED assembly

PINPOINT TEST AR: 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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AR1 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 AR2.

No
REMOVE the obstruction or CLEAN the filter. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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AR2 CHECK THE OPERATION OF THE SEAT AND MONITOR SEAT TEMPERATURE USING THE SCAN TOOL

- Enter the following diagnostic mode on the scan tool: DataLogger - DCSM - PIDs.

- 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. REPEAT the self-test.

No
If the seat is operational, but the backrest temperature increases greater than the cushion, GO to AR3.

If the seat does not operate, GO to AR4.

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AR3 CHECK THE TED FOR CORRECT INSTALLATION AND FOR A CRUSHED FOAM PAD

- Remove the seat backrest cover. Refer to Seat Backrest Cover - Front Seat Backrest Cover - Front.
- Check the TED and climate controlled seat manifold (part of foam pad) for damage, restriction and for correct installation.
- Is the TED correctly installed and foam pad OK?

Yes
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device - Front Row Seat Backrest Thermo-Electric Device - Front Row. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

No
CORRECTLY install the backrest TED or INSTALL a new foam pad. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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AR4 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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Passenger Seat Side Air Bag Module C3377.
- Disconnect: Passenger Seat Safety Belt Buckle Pretensioner C3066.
- 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 AR5.

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

DISCONNECT the battery ground cable.

CONNECT passenger seat safety belt buckle pretensioner C3066.

CONNECT passenger seat side air bag module C3377.

REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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AR5 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 AR6.

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

DISCONNECT the battery ground cable.

CONNECT passenger seat safety belt buckle pretensioner C3066.

CONNECT passenger seat side air bag module C3377.

REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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AR6 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 cushion TED. REFER to Seat Cushion Thermo-Electric Device - Front Row Seat Cushion Thermo-Electric Device - Front Row. CLEAR the DTCs. REPEAT the self-test.

DISCONNECT the battery ground cable.

CONNECT passenger seat safety belt buckle pretensioner C3066.

CONNECT passenger seat side air bag module C3377.

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 safety belt buckle pretensioner C3066.

CONNECT passenger seat side air bag module C3377.

REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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