Part 2
Seats
Pinpoint Test AK: DTC B272B
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 (Dual Climate Controlled Seat Module), diagnostic testing can be carried out with the ignition ON. The system receives voltage from Battery Junction Box (BJB) fuse 22 (30A) supplying voltage into DCSM (Dual Climate Controlled Seat Module) C3265a pins E and F, circuit CBX01 (GN/RD). If voltage is disconnected from either pin E or F of DCSM (Dual Climate Controlled Seat Module) C3265a both seats will remain operational because the voltage supply circuits are connected internally in the DCSM (Dual Climate Controlled Seat Module). However, if a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat will be disabled by the DCSM (Dual Climate Controlled Seat Module).
The 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 (Thermo-Electric Device)). Cabin air is drawn through the blower and distributed to each of the TED (Thermo-Electric Device) modules. The TEDs (Thermo-Electric Devices) 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 (Dual Climate Controlled Seat Module) 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 (Thermo-Electric Device) temperature exceeds 70°C (158°F) for more than 34 seconds, the TED (Thermo-Electric Device) is disconnected or the duct is blocked, the DCSM (Dual Climate Controlled Seat Module) 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 (Thermo-Electric Device) temperature exceeds 85°C (185°F) for more than 34 seconds, the TED (Thermo-Electric Device) is disconnected or the duct is blocked, the DCSM (Dual Climate Controlled Seat Module) 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 (Thermo-Electric Device) filter
- Crushed or restricted backrest foam pad
- Crushed or restricted climate controlled seat manifold
- Backrest TED (Thermo-Electric Device) assembly
- DCSM (Dual Climate Controlled Seat Module)
PINPOINT TEST AK : DTC B272B
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.
AK11 CHECK THE PASSENGER SEAT BACKREST BLOWER CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between DCSM (Dual Climate Controlled Seat Module) C3265C-8, circuit CHS08 (BN/YE), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to AK12.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK12 CHECK THE PASSENGER SEAT BACKREST BLOWER CIRCUITS FOR AN OPEN
- Measure the resistance between:
- DCSM (Dual Climate Controlled Seat Module) C3265C-8, circuit CHS08 (BN/YE), harness side and passenger seat backrest TED (Thermo-Electric Device) C3039-2, circuit CHS03 (GN/BN), harness side.
- DCSM (Dual Climate Controlled Seat Module) C3265C-7, circuit RHS08 (VT/WH), harness side and passenger seat backrest TED (Thermo-Electric Device) C3039-4, circuit RHS03 (GY/OG), harness side.
Are the resistances less than 5 ohms?
Yes
GO to AK13.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK13 CHECK THE PASSENGER SEAT BACKREST 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 results in false readings and leads to incorrect identification of components that are not damaged.
Measure the resistance between passenger seat backrest TED (Thermo-Electric Device) C3039 pin 2 and pin 4, component side.
Is the resistance between 4,000 ohms and 10,000 ohms?
Yes
GO to AK14.
No
INSTALL a new passenger seat backrest TED (Thermo-Electric Device). REFER to Seat Backrest Thermo-Electric Device . CLEAR the DTCs. REPEAT the self-test.
CONNECT passenger seat safety belt buckle pretensioner C3066.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK14 CHECK THE PASSENGER SEAT BACKREST 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 results in false readings and leads to incorrect identification of components that are not damaged.
Measure the resistance between passenger seat backrest TED (Thermo-Electric Device) C3039 pin 7 and pin 4, component side.
Is the resistance between 240K ohms and 400K ohms?
Yes
GO to AK15.
No
INSTALL a new passenger seat backrest TED (Thermo-Electric Device). REFER to Seat Backrest Thermo-Electric Device . CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK15 CHECK THE PASSENGER SEAT BACKREST TED (Thermo-Electric Device) INSTALLATION AND FOR CRUSHED SEAT BACKREST
- Ignition OFF.
- Remove the passenger seat. Refer to Seat- Front .
- Remove the passenger seat backrest cover. Refer to Seat Backrest Cover- Front .
- Inspect the passenger seat backrest for the following:
- Is the passenger seat backrest TED (Thermo-Electric Device) correctly installed?
- Is the passenger seat backrest foam pad crushed or restricted?
- Is the passenger seat backrest climate controlled seat manifold crushed or restricted?
Is the passenger seat backrest TED (Thermo-Electric Device) correctly installed and are there no signs of damage to the foam pad and manifold?
Yes
INSTALL the passenger seat backrest cover and seat and GO to AK18.
No
CORRECTLY install the passenger seat backrest TED (Thermo-Electric Device) or INSTALL a new passenger seat backrest foam pad and/or climate controlled seat manifold. CONNECT the battery ground cable. REFER to Battery. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK16 CHECK THE PASSENGER SEAT BACKREST TED (Thermo-Electric Device) THERMISTOR AND WIRING
- Ignition OFF.
- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Restraints and Safety Systems &/or Air Bag Systems.
- Disconnect: Passenger Seat Side Air Bag C3133.
- Disconnect: Passenger Seat Safety Belt Buckle Pretensioner C3066.
- Disconnect: DCSM (Dual Climate Controlled Seat Module) C3265B.
- 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 (Dual Climate Controlled Seat Module) C3265B-4, circuit VHS36 (YE/BU), harness side and C3305B-5 circuit RHS20 (GN/BU), harness side. Note the ambient temperature and refer to the following table.
Temperature Resistance 0-10°C (32-50°F) 2,782-1,663 ohms 10-20°C (50-68°F) 1,837-1,140 ohms 20-30°C (68-86°F) 1,260-806 ohms 30-40°C (86-104°F) 893-570 ohms 40-50°C (104-122°F) 630-428 ohms
Is the resistance within the limits indicated?
Yes
GO to AK18.
No
GO to AK17.
AK17 CHECK THE PASSENGER SEAT BACKREST TED (Thermo-Electric Device) THERMISTOR
- Measure the resistance between passenger seat backrest TED (Thermo-Electric Device) C3039 pin 5 and pin 8, component side. Note the ambient temperature and refer to the following table.
Temperature Resistance 0-10°C (32-50°F) 2,782-1,663 ohms 10-20°C (50-68°F) 1,837-1,140 ohms 20-30°C (68-86°F) 1,260-806 ohms 30-40°C (86-104°F) 893-570 ohms 40-50°C (104-122°F) 630-428 ohms
Is the resistance within the limits indicated?
Yes
REPAIR circuit VHS35 (VT/OG) or RHS15 (GY/BN) for an open or high resistance. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
No
INSTALL a new TED (Thermo-Electric Device). REFER to Seat Backrest Thermo-Electric Device . CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK18 CHECK THE PASSENGER SEAT BACKREST TED (Thermo-Electric Device) HEATING/COOLING CIRCUITRY CURRENT DRAW
- Connect: All DCSM (Dual Climate Controlled Seat Module), TED (Thermo-Electric Device) and Body Harness-to-Seat Harness Connectors.
- NOTICE: It may be necessary to open the seat wire harness conduit to allow placing the inductive current probe around the circuit as described in the following step. Care must be taken when opening up the wire harness so as not to damage any wiring or connectors. Do not damage any wiring or induce stress on any wiring or connectors. Close up the wire harness once repairs to the seat are complete.
NOTE: Use a commercially available inductive current probe (such as Electronic Specialties Current Probe/Multimeter 685 or a Fluke I410 [used with a digital multimeter]) or the low current probe from the Vehicle Measurement Module available for use with Integrated Diagnostic System (IDS). If these are unavailable, the inductive current probe feature from a battery tester may be substituted.
Place an inductive current probe around circuit CHS06 (BU/BN) near DCSM (Dual Climate Controlled Seat Module) C3305A-C and monitor the current draw.
- Start the vehicle and set the passenger seat to HIGH heat.
Is the current draw less than 11 amps?
Yes
GO to AK19.
No
INSTALL a new passenger seat backrest TED (Thermo-Electric Device). REFER to Seat Backrest Thermo-Electric Device . CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK19 CHECK RESISTANCE OF THE PASSENGER SEAT BACKREST TED (Thermo-Electric Device) AND WIRING
- Ignition OFF.
- Disconnect: DCSM (Dual Climate Controlled Seat Module) C3265A.
- Measure the resistance between DCSM (Dual Climate Controlled Seat Module) C3265A-C circuit CHS06 (BU/BN), harness side and C3265A-D, circuit RHS06 (WH), harness side.
Is the resistance between 0.9 and 10 ohms?
Yes
GO to AK21.
No
GO to AK20.
AK20 CHECK THE RESISTANCE OF THE PASSENGER SEAT BACKREST TED (Thermo-Electric Device)
- Disconnect: Passenger Seat Backrest TED (Thermo-Electric Device) C3039.
- Measure the resistance between passenger seat backrest TED (Thermo-Electric Device) C3039 pin 1 and pin 3, component side.
Is the resistance between 0.9 and 10 ohms?
Yes
REPAIR circuit CHS01 (GY/VY) or RHS01 (WH/VT) for an open or high resistance. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
No
INSTALL a new passenger seat backrest TED (Thermo-Electric Device). REFER to Seat Backrest Thermo-Electric Device . CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AK21 CHECK FOR CORRECT DCSM (Dual Climate Controlled Seat Module) OPERATION
- Inspect the DCSM (Dual Climate Controlled Seat Module) and passenger seat backrest TED (Thermo-Electric Device) harness and component side connectors and the body harness-to-seat harness connectors for:
- corrosion
- damaged pins
- pushed-out pins
- Connect: All DCSM (Dual Climate Controlled Seat Module), TED (Thermo-Electric Device) and Body Harness-to-Seat Harness Connectors.
- Make sure the connectors are seated correctly.
- Start the engine.
- Set the passenger seat to OFF.
- Enter the following diagnostic mode on the scan tool: Clear DTCs - DCSM (Dual Climate Controlled Seat Module).
- Attempt to recreate the fault. With the engine still running set the passenger seat to HIGH heat for at least 15 minutes.
Is the concern still present?
Yes
INSTALL a new DCSM (Dual Climate Controlled Seat Module). REFER to Dual Climate Controlled Seat Module (DCSM) . REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.