Pinpoint Test AL: DTC B272B
Seats
Pinpoint Tests
Pinpoint Test AL: DTC B272B
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
Climate controlled seats are independently controlled by the Dual Climate Controlled Seat Module (DCSM) mounted to the bottom of the passenger seat cushion. The climate controlled seat system only operates with the engine running, however, if using a scan tool to command the DCSM, diagnostic testing can be carried out with the ignition KOEO. The system receives voltage from Battery Junction Box (BJB) fuse 12 (30A) supplying battery voltage on circuit SBB12 (GN/RD) into DCSM C3305a pin F. The system also receives voltage from BJB fuse 11 (30A) supplying battery voltage on circuit SBB11 (BU/RD) into DCSM C3305a pin E. If voltage is disconnected from either pin E or F of DCSM C3305a with the voltage connection remaining on the other circuit, both seats will remain operational because the voltage supply circuits are connected internally in the DCSM. However, if a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat will be disabled by the module and the other will remain operational.
The seat cushion is equipped with a Thermo-Electric Device (TED) assembly that includes a seat blower (fan motor, serviced as an assembly with the TED). Similarly, the seat backrest is also equipped with its own TED assembly with blower. Cabin air is drawn through the blower and distributed to each of the TED modules located in the seat cushion and backrest. The TEDs then heat or cool the air. The air is then directed into the foam pad and manifold where it is distributed along the surface of the cushion and backrest of the seat. Once the system is activated, the DCSM uses a set of flexible algorithms to control the heating/cooling modes and the blower speed dependant on the HVAC module seat switch settings.
- DTC B272B Passenger Back Over-Temp Detected - In the cooling mode, if the passenger seat backrest 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 passenger seat system and set this DTC.
- DTC B272B Passenger Back Over-Temp Detected - In the heating mode, if the passenger seat backrest 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 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 backrest foam pad
- Crushed or restricted climate controlled seat manifold
- Backrest TED assembly
- DCSM
PINPOINT TEST AL: DTC B272B
NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition switch 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 FOR DCSM DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - DCSM.
- Was DTC B2730 retrieved?
Yes
GO to AL2.
No
GO to AL4.
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AL2 CHECK BACKREST TED THERMISTOR CIRCUITS 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 Air Bag Systems.
- Disconnect: Passenger Seat Side Air Bag Module C313.
- Disconnect: DCSM C3305b.
- Disconnect: Backrest TED C3311.
- Measure resistance between:
- DCSM C3305b-4, circuit VHS36 (YE/BU), harness side and ground.
- DCSM C3305b-5, circuit RHS20 (GN/BU), harness side and ground.
- Are resistances greater than 10,000 ohms?
Yes
GO to AL3.
No
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL3 CHECK BACKREST TED THERMISTOR RESISTANCE
- Measure resistance between backrest TED C3311 pin 5 and pin 8, component side. Note the ambient temperature and compare result to the following table:
- Is resistance within the limits indicated?
Yes
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
No
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL4 CONFIRM THE FAULT
- Verify with the customer that the concern is the seat shuts OFF in heat mode.
- NOTE: A crushed seat backrest foam pad or a crushed climate controlled seat manifold may be the cause of the fault. It may be necessary to sit on the seat or place something of reasonable size and weight on the seat to recreate the fault.
- Attempt to recreate the fault. Start the vehicle and set the front passenger seat to high heat for at least 15 minutes.
- Is the customer concern with the seat shutting OFF in heat mode or was the fault recreated?
Yes
GO to AL5.
No
Fault not present. Fault may have been set due to a past failure or incorrect use of the climate controlled seat system by repeated switching between HEAT and COOL modes. REPEAT the self-test. CLEAR the DTCs.
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AL5 CHECK OPERATION OF THE SEAT
- Ignition ON.
- With the engine running, set both front seats to high cool (3 indicators illuminated on HVAC module).
- Compare the airflow from the front passenger seat backrest and compare it to the airflow from the driver seat backrest.
- Is the airflow exhausting from the front passenger seat backrest comparable to the airflow exhausting from the driver seat backrest?
Yes
GO to AL14.
No
GO to AL6.
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AL6 CHECK BACKREST BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER
- Ignition OFF.
- Inspect blower of the backrest TED assembly for an obstruction or for a restricted filter.
- Is the blower clear of obstruction and filter clean?
Yes
GO to AL7.
No
REMOVE the obstruction or INSTALL a new filter. REPEAT the self-test. CLEAR the DTCs.
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AL7 CHECK BACKREST FAN OPERATION
- Ignition ON.
- With the engine running, set both front seats to high cool (3 indicators illuminated on HVAC module).
- Inspect the backrest blower for operation.
- Does the backrest blower operate?
Yes
GO to AL14.
No
GO to AL8.
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AL8 CHECK BLOWER SPEED CONTROL CIRCUIT VHS21 (BU/WH) FOR AN OPEN
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Air Bag Systems.
- Disconnect: Passenger Seat Side Air Bag Module C313.
- Disconnect: DCSM C3305c.
- Disconnect: Backrest TED C3311.
- Measure resistance between DCSM C3305c-4, circuit VHS21 (BU/WH), harness side and backrest TED C3310-7, circuit VHS21 (BU/WH), harness side.
- Is resistance less than 5 ohms?
Yes
GO to AL9.
No
REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL9 CHECK BLOWER CIRCUIT RHS08 (VT/WH) FOR A SHORT TO VOLTAGE
- 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.
- Connect the battery ground cable. Refer to Battery.
- Ignition ON.
- Measure voltage between DCSM C3305c-7, circuit RHS08 (VT/WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
No
GO to AL10.
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AL10 CHECK BLOWER CIRCUIT CHS08 (BN/YE) FOR A SHORT TO GROUND
- Ignition OFF.
- Measure resistance between DCSM C3305c-8, circuit CHS08 (BN/YE), harness side and ground.
- Is resistance greater than 10,000 ohms?
Yes
GO to AL11.
No
REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL11 CHECK BLOWER CIRCUITS CHS08 (BN/YE) AND RHS08 (VT/WH) FOR AN OPEN
- Measure resistance between:
- DCSM C3305c-8, circuit CHS08 (BN/YE), harness side and backrest TED C3311-2, circuit CHS08 (BN/YE), harness side.
- DCSM C3305c-7, circuit RHS08 (VT/WH), harness side and backrest TED C3311-4, circuit RHS08 (VT/WH), harness side.
- Are resistances less than 5 ohms?
Yes
GO to AL12.
No
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL12 CHECK BACKREST BLOWER RESISTANCE
- NOTE: The ohmmeter must be connected with the positive lead to pin 2 and the negative lead to pin 4 when measuring. Ohmmeter leads incorrectly connected will result in false readings and lead to incorrect identification of components that are not faulty.
- Measure resistance between backrest TED C3311 pin 2 and pin 4, component side.
- Is resistance between 6K ohms and 9K ohms?
Yes
GO to AL13.
No
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL13 CHECK BACKREST BLOWER SPEED CONTROL RESISTANCE
- NOTE: The ohmmeter must be connected with the positive lead to pin 7 and the negative lead to pin 4 when measuring. Ohmmeter leads incorrectly connected will result in false readings and lead to incorrect identification of components that are not faulty.
- Measure resistance between backrest TED C3311 pin 7 and pin 4, component side.
- Is resistance between 290K ohms and 420K ohms?
Yes
GO to AL14.
No
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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AL14 CHECK TED FOR CORRECT INSTALLATION AND FOR CRUSHED FOAM
- Ignition OFF.
- Remove the seat. Refer to Seat - Front Seat - Front.
- Remove the seat backrest trim cover. Refer to Seat Backrest Cover - Front, Without Fold Flat Seat Backrest Cover - Front, Without Fold Flat.
- Inspect the seat backrest for the following:
- Is the TED correctly installed?
- Is the seat backrest foam pad crushed or restricted?
- Is the climate controlled seat manifold crushed or restricted?
- Is the TED correctly installed and the foam pad and manifold OK?
Yes
INSTALL a new DCSM and CARRY OUT Programmable Module Installation (PMI). REFER to Dual Climate Controlled Seat Module (DCSM) Dual Climate Controlled Seat Module (DCSM). REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
No
CORRECTLY install the backrest TED or INSTALL a new seat backrest foam pad and/or climate controlled seat manifold. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.
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