Pinpoint Test AR: DTC B272A
Seats
Pinpoint Tests
Pinpoint Test AR: DTC B272A
Refer to Wiring Diagrams Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
Both the driver and front passenger climate controlled seats are independently controlled electronically 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 switch ON and the engine OFF. The system receives voltage from Battery Junction Box (BJB) fuse 16 (30A) supplying battery voltage on circuit SBB16 (VT/RD) into DCSM C3036a pins E and F. If voltage is disconnected from either pin E or F of DCSM C3036a with the connection remaining on the other circuit, both seats will remain operational because the 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 DCSM and the other will remain operational.
Each driver and front passenger seat cushion and backrest are equipped with a Thermo-Electric Device (TED) assembly that includes a seat blower (fan motor, serviced as an assembly with the TED). 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 B272A (Passenger Cushion Over-Temp Detected) - In the cooling mode, if the passenger seat cushion TED temperature exceeds 70°C (158°F) for more than 4 seconds, the TED is disconnected or the duct is blocked, the DCSM will shut down the passenger seat system and set this DTC.
- DTC B272A (Passenger Cushion Over-Temp Detected) - In the heating mode, if the passenger seat cushion TED temperature exceeds 85°C (185°F) for more than 4 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 cushion TED filter
- Crushed or restricted cushion foam pad
- Crushed or restricted climate controlled seat manifold
- Cushion TED assembly
- DCSM
PINPOINT TEST AR: DTC B272A
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: 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 DCSM FOR DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - DCSM.
- Was DTC B272A retrieved during the self-test?
Yes
GO to AR2.
No
GO to AR4.
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AR2 CHECK THE 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 C327.
- Disconnect: DCSM C3036b.
- Disconnect: Cushion TED C3328.
- 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.
- Measure the resistance between:
- DCSM C3036b-2, circuit VHS27 (WH/OG), harness side and ground.
- DCSM C3036b-3, circuit RHS10 (BU/OG), harness side and ground.
- Are the resistances greater than 10,000 ohms?
Yes
GO to AR3.
No
REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR3 CHECK THE TED THERMISTOR
- Measure the resistance between cushion TED C3328 pin 5 and pin 8, component side. Note the ambient temperature and refer to the following table.
- Is the resistance within the limits indicated?
Yes
REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
No
INSTALL a new cushion TED.
REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR4 CONFIRM THE FAULT
- Verify with the customer that the concern is the seat shuts OFF in heat mode.
- NOTE: A crushed seat cushion 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 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 AR5.
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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AR5 CHECK OPERATION OF THE SEAT
- Ignition ON.
- With the engine running, set both front seats to HIGH cool (3 LEDs illuminated on HVAC module).
- Compare the airflow from the passenger seat cushion and compare it to the airflow from the driver seat cushion.
- Is the airflow exhausting from the passenger seat cushion comparable to the airflow exhausting from the driver seat cushion?
Yes
GO to AR14.
No
GO to AR6
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AR6 CHECK THE CUSHION BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER
- Ignition OFF.
- Inspect the blower of the cushion TED assembly for an obstruction or for a restricted filter.
- Is the blower obstructed or the filter restricted?
Yes
REMOVE the obstruction or INSTALL a new filter. REPEAT the self-test. CLEAR the DTCs.
No
GO to AR7.
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AR7 CHECK THE CUSHION FAN OPERATION
- Ignition ON.
- With the engine running, set both front seats to HIGH cool (3 LEDs illuminated on HVAC module).
- Inspect the cushion blower for operation.
- Does the cushion blower operate?
Yes
GO to AR14.
No
GO to AR8.
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AR8 CHECK THE BLOWER SPEED CONTROL CIRCUIT 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 C327.
- Disconnect: DCSM C3036c.
- Disconnect: Cushion TED C3328.
- Measure the resistance between DCSM C3036c-3, circuit VHS23 (BN/BU), harness side and cushion TED C3328-7, circuit VHS23 (BN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to AR9.
No
REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR9 CHECK THE 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.
- Ignition ON.
- Measure the voltage between DCSM C3036c-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 C327.
REPOWER the SRS. REFER to Air Bag Systems.
No
GO to AR10.
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AR10 CHECK BLOWER CIRCUIT CHS08 (BN/YE) FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between DCSM C3036c-8, circuit CHS08 (BN/YE), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AR11.
No
REPAIR the circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR11 CHECK BLOWER CIRCUITS CHS08 (BN/YE) AND RHS08 (VT/WH) FOR AN OPEN
- Measure the resistance between:
- DCSM C3036c-8, circuit CHS08 (BN/YE), harness side and cushion TED C3328-2, circuit CHS08 (BN/YE), harness side.
- DCSM C3036c-7, circuit RHS08 (VT/WH), harness side and cushion TED C3328-4, circuit RHS08 (VT/WH), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to AR12.
No
REPAIR the affected circuit. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR12 CHECK THE BLOWER RESISTANCE
- NOTICE: 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 the resistance between cushion TED C3328 pin 2 and pin 4, component side.
- Is the resistance between 4,000 ohms and 10,000 ohms?
Yes
GO to AR13.
No
INSTALL a new cushion TED. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR13 CHECK THE BLOWER SPEED CONTROL RESISTANCE
- NOTICE: 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 the resistance between cushion TED C3328 pin 7 and pin 4, component side.
- Is the resistance between 240,000 ohms and 420,000 ohms?
Yes
GO to AR14.
No
INSTALL a new cushion TED. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
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AR14 CHECK THE TED INSTALLATION AND FOR CRUSHED SEAT CUSHION
- Ignition OFF.
- Remove the seat.
- Remove the seat cushion cover.
- Inspect the seat cushion for the following:
- Is the TED correctly installed?
- Is the seat cushion foam pad crushed or restricted?
- Is the climate controlled seat manifold crushed or restricted?
- Is the TED correctly installed and are there no signs of damage to the foam pad and manifold?
Yes
CONNECT the battery ground cable.
INSTALL a new DCSM. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.
No
Correctly INSTALL the cushion TED or INSTALL a new seat cushion foam pad and/or climate controlled seat manifold. INSTALL the passenger seat. CONNECT the battery ground cable. REPEAT the self-test. CLEAR the DTCs.
DISCONNECT the battery ground cable.
CONNECT passenger seat side air bag module C327.
REPOWER the SRS. REFER to Air Bag Systems.