Pinpoint Test AQ: DTC B2729
Seats
Pinpoint Tests
Pinpoint Test AQ: DTC B2729
Refer to Wiring Diagram 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 ON engine OFF. The system receives voltage from Battery Junction Box (BJB) fuse 67 (40A) feeding battery voltage on circuit SBB08 (VT/RD) into DCSM C3265A pins E and F. If voltage is disconnected from either pin E or F of DCSM C3265A with the voltage connection remaining on the other circuit, both seats will remain operational because the voltage feed 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.
Each driver and front passenger 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, each driver and front passenger 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 climate controlled seat switch settings.
- DTC B2729 (Cushion Over-Temp Detected) - In the heating mode, if the driver 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 driver seat system and set this DTC.
- DTC B2729 (Cushion Over-Temp Detected) - In the cooling mode, if the driver 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 driver 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 AQ: DTC B2729
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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AQ1 CHECK THE DCSM FOR ON-DEMAND DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - DCSM.
- Was DTC B2729 retrieved on-demand during the self-test?
Yes
GO to AQ2.
No
GO to AQ4.
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AQ2 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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Seat Safety Belt Buckle Pretensioner C3049 and Passenger Seat Safety Belt Buckle Pretensioner C3050.
- Disconnect: Driver Seat Side Air Bag C3051 and Passenger Seat Side Air Bag C3052.
- Disconnect: DCSM C3265B.
- Disconnect: Cushion TED C3035.
- 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, Mounting and Cables Battery Disconnect.
- Measure the resistance between:
- DCSM C3265B-7, circuit VHS26 (VT), harness side and ground.
- DCSM C3265B-8, circuit RHS05 (YE/VT), harness side and ground.
- Are the resistances greater than 10,000 ohms?
Yes
GO to AQ3.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ3 CHECK THE TED THERMISTOR
- Measure the resistance between cushion TED C3035 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 open circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ4 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 driver 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 AQ5.
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. CLEAR the DTCs. REPEAT the self-test.
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AQ5 CHECK OPERATION OF THE SEAT
- Ignition ON.
- With the engine running, set both front seats to HIGH cool.
- Compare the airflow from the driver seat cushion and compare it to the airflow from the passenger seat cushion.
- Is the airflow exhausting from the driver seat cushion comparable to the airflow exhausting from the passenger seat cushion?
Yes
GO to AQ14.
No
GO to AQ6.
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AQ6 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. CLEAR the DTCs. REPEAT the self-test.
No
GO to AQ7.
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AQ7 CHECK THE CUSHION FAN OPERATION
- Ignition ON.
- With the engine running, set both front seats to HIGH cool.
- Inspect the cushion blower for operation.
- Does the cushion blower operate?
Yes
GO to AQ14.
No
GO to AQ8.
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AQ8 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 Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Seat Safety Belt Buckle Pretensioner C3049 and Passenger Seat Safety Belt Buckle Pretensioner C3050.
- Disconnect: Driver Seat Side Air Bag C3051 and Passenger Seat Side Air Bag C3052.
- Disconnect: DCSM C3265C.
- Disconnect: Cushion TED C3035.
- 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, Mounting and Cables Battery Disconnect.
- Measure the resistance between DCSM C3265C-11, circuit CHS03 (GN/BN), harness side and cushion TED C3035-7, circuit CHS03 (GN/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to AQ9.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ9 CHECK THE BLOWER CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between DCSM C3265C-15, circuit CHS03 (GN/BN), harness side and ground.
- Is voltage present on any circuit?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
No
GO to AQ10.
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AQ10 CHECK THE BLOWER CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between DCSM C3265C-16, circuit CHS13 (VT/BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to AQ11.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ11 CHECK THE BLOWER CIRCUITS FOR AN OPEN
- Measure the resistance between:
- DCSM C3265C-16, circuit CHS13 (VT/BN), harness side and cushion TED C3035-2, circuit CHS13 (VT/BN), harness side.
- DCSM C3265C-15, circuit CHS03 (GN/BN), harness side and cushion TED C3035-4, circuit CHS03 (GN/BN), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to AQ12.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ12 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 C3035 pin 2 and pin 4, component side.
- Is the resistance between 4,000 ohms and 10,000 ohms?
Yes
GO to AQ13.
No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ13 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 C3035 pin 7 and pin 4, component side.
- Is the resistance between 240K ohms and 420K ohms?
Yes
GO to AQ14.
No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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AQ14 CHECK THE TED INSTALLATION AND FOR CRUSHED SEAT CUSHION
- 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.
- Remove the seat. Refer to Seat - Front Seat - Front.
- Remove the seat cushion cover. Refer to Seat Cushion Cover - Front Seat Cushion Cover - Front.
- 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. REFER to Battery, Mounting and Cables Battery Disconnect.
INSTALL a new DCSM. REFER to Dual Climate Controlled Seat Module (DCSM) Dual Climate Controlled Seat Module (DCSM). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
No
CORRECTLY install the cushion TED or INSTALL a new seat cushion foam pad and/or climate controlled seat manifold. CONNECT the battery ground cable. REFER to Battery, Mounting and Cables Battery Disconnect. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle pretensioner C3049 and passenger seat safety belt buckle pretensioner C3050.
CONNECT driver seat side air bag module C3051 and passenger seat side air bag module C3052.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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