Pinpoint Test BL: DTC B2729

Seats

Pinpoint Test BL: DTC B2729

Normal Operation

The Passenger Climate Controlled Seat Module - 2 (PCSM-2) 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 B2729 (Cushion Over-Temp Detected)- For heat mode, if the driver seat cushion TED (Thermo-Electric Device) temperature exceeds 110°C (230°F) continuously for more than 4 seconds in any heat mode, the DCSM (Dual Climate Controlled Seat Module) turns off the TED (Thermo-Electric Device) and enters a fan only state to recover from the over-temperature condition (recovery mode). If the TED (Thermo-Electric Device) temperature does not recover after 30 seconds, the DTC will set and the seat is disabled. If the TED (Thermo-Electric Device) does recover, the TED (Thermo-Electric Device) 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 B2729 (Cushion Over-Temp Detected)- For cool mode, if the driver seat cushion TED (Thermo-Electric Device) temperature exceeds 65°C (149°F) continuously for more than 4 seconds in any cool mode, the DCSM (Dual Climate Controlled Seat Module) turns off the TED (Thermo-Electric Device) and enters a fan only state to recover from the over-temperature condition (recovery mode). If the TED (Thermo-Electric Device) temperature does not recover after 5 minutes, the DTC will set and the seat is disabled. If the TED (Thermo-Electric Device) does recover, the TED (Thermo-Electric Device) 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 cushion TED (Thermo-Electric Device) filter

- Crushed or restricted foam pad

- Cushion TED (Thermo-Electric Device) assembly

- PCSM-2 (Passenger Climate Controlled Seat Module - 2)

PINPOINT TEST BL : DTC B2729

NOTICE: When taking measurements at PCSM-2 (Passenger Climate Controlled Seat Module - 2) 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.

BL1 CHECK THE PCSM-2 (Passenger Climate Controlled Seat Module - 2) FOR ON-DEMAND DTCs

- Start the vehicle and set the driver side rear seat to HIGH heat.

- Enter the following diagnostic mode on the scan tool: Self Test- PCSM-2 (Passenger Climate Controlled Seat Module - 2).

Was DTC B2729 retrieved on-demand during the self-test?

Yes
GO to BL2.

No
GO to BL5.

BL2 CHECK THE DRIVER SIDE REAR SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365B.

- Disconnect: Driver Seat Cushion TED (Thermo-Electric Device) C3358.

- Measure the resistance between:
- DCSM (Dual Climate Controlled Seat Module) C3365B-7, circuit VHS42 (GN), harness side and ground.

- DCSM (Dual Climate Controlled Seat Module) C3365B-8, circuit RHS42 (BN/WH), harness side and ground.

Are the resistances greater than 10,000 ohms?

Yes
GO to BL3.

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

BL3 CHECK THE DRIVER SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR AND WIRING

- Connect: Driver Seat Cushion TED (Thermo-Electric Device) C3358.

- Measure the resistance between PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365B-7, circuit VHS42 (GN), harness side and DCSM (Dual Climate Controlled Seat Module) C3365B-8, circuit RHS42 (BN/WH), 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 BL18.

No
GO to BL4.

BL4 CHECK THE DRIVER SIDE REAR SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR

- Disconnect: Driver Side Rear Seat Cushion TED (Thermo-Electric Device) C3358.

- Measure the resistance between driver side rear seat cushion TED (Thermo-Electric Device) C3358 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 VHS42 (GN) or RHS42 (BN/WH) for an open or high resistance. CLEAR the DTCs. REPEAT the self-test.

No
INSTALL a new driver side rear seat cushion TED (Thermo-Electric Device). REFER to Seat Cushion Thermo-Electric Device - Second Row . CLEAR the DTCs. REPEAT the self-test.

BL5 CONFIRM THE FAULT WHILE MONITORING THE PCSM-2 (Passenger Climate Controlled Seat Module - 2) SEAT BACK THERMAL ELECTRIC DEVICE TEMPERATURE (BK_TEMP) AND SEAT CUSHION THERMAL ELECTRIC DEVICE TEMPERATURE (CSHTEMP) PIDs

- Set the driver side rear seat to OFF.

- Enter the following diagnostic mode on the scan tool: Clear DTCs - PCSM-2 (Passenger Climate Controlled Seat Module - 2).

- Enter the following diagnostic mode on the scan tool: DataLogger - PCSM-2 (Passenger Climate Controlled Seat Module - 2).

- Monitor the PCSM-2 (Passenger Climate Controlled Seat Module - 2) PIDs BK_TEMP and CSHTEMP.

- NOTE: A crushed seat cushion foam pad or a crushed climate controlled seat manifold may be the cause of the fault making it necessary to occupy the seat to recreate and identify the fault.
Attempt to recreate the fault. Start the vehicle and set the driver side rear seat to HIGH heat for at least 15 minutes while occupying the seat.

Do the PIDs increase incrementally (gradually) and stay within 15°C (27°F) of each other?

Yes
Fault not present at this time. Fault may have been set due to a past failure, incorrect use of the climate controlled seat system by repeated switching between heat and cool modes or due to excessive passenger compartment temperature. CLEAR the DTCs. REPEAT the self-test.

No
If the CSHTEMP PID increases incrementally and is greater than 15°C (27°F) of the BK_TEMP PID, GO to BL6.

If the CSHTEMP PID increases quickly (temperature "jumps" and does not increase incrementally) and is greater than 15°C (27°F) of the BK_TEMP PID, GO to BL16.

BL6 COMPARE OPERATION OF THE DRIVER AND PASSENGER SIDE REAR SEATS

- With the engine running, set both rear seats to HIGH cool.

- Note the airflow exhausting from the driver side rear seat cushion TED (Thermo-Electric Device) and compare it to the airflow exhausting from the passenger side rear seat cushion TED (Thermo-Electric Device).

- Carry out a wiggle test of the wire harnesses between the PCSM-2 (Passenger Climate Controlled Seat Module - 2) and the driver side rear seat cushion TED (Thermo-Electric Device) while monitoring blower operation of the TED (Thermo-Electric Device). The blower should operate consistently and not change speeds

Is the airflow exhausting from the driver side rear seat cushion TED (Thermo-Electric Device) comparable to the airflow exhausting from the passenger side rear seat cushion TED (Thermo-Electric Device) with no change in operation when carrying out the wiggle test?

Yes
GO to BL7.

No
If the airflow exhausting from the driver side rear seat cushion TED (Thermo-Electric Device) is not comparable to the airflow exhausting from the passenger side rear seat cushion TED (Thermo-Electric Device), GO to BL8.

If the driver side rear seat cushion TED (Thermo-Electric Device) blower operation changed while carrying out the wiggle test, IDENTIFY and REPAIR the wiring fault. CLEAR the DTCs. REPEAT the self-test.

BL7 COMPARE OPERATION OF THE DRIVER AND PASSENGER SIDE REAR SEATS WHILE OCCUPIED

- Note the airflow exhausting from the driver side rear seat cushion TED (Thermo-Electric Device) with the seat occupied and compare it to the airflow exhausting from the passenger side rear seat cushion TED (Thermo-Electric Device) with the passenger seat occupied.

Is the airflow exhausting from the driver side rear seat cushion TED (Thermo-Electric Device) comparable to the airflow exhausting from the passenger side rear seat cushion TED (Thermo-Electric Device)?

Yes
GO to BL16.

No
INSTALL a new seat cushion foam pad and/or climate controlled seat manifold. CLEAR the DTCs. REPEAT the self-test.

BL8 CHECK THE DRIVER SIDE REAR SEAT CUSHION BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER

- Ignition OFF.

- Inspect the blower of the driver side rear seat cushion TED (Thermo-Electric Device) 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 BL9.

BL9 CHECK THE DRIVER SEAT CUSHION BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN

- Disconnect: PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365C.

- Disconnect: Driver Seat Cushion TED (Thermo-Electric Device) C3358.

- Measure the resistance between PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365C-11, circuit VHS70 (YE), harness side and driver side rear seat cushion TED (Thermo-Electric Device) C3358-7, circuit VHS70 (YE), harness side.

Is the resistance less than 5 ohms?

Yes
GO to BL10.

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

BL10 CHECK THE DRIVER SIDE REAR SEAT CUSHION BLOWER CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition ON.

- Measure the voltage between PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365C-15, circuit RHS67 (WH/BU), harness side and ground.

Is any voltage present?

Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

No
GO to BL11.

BL11 CHECK THE DRIVER SIDE REAR SEAT CUSHION BLOWER CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365C-16, circuit CHS67 (VT/BN), harness side and ground.

Is the resistance greater than 10,000 ohms?

Yes
GO to BL12.

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

BL12 CHECK THE DRIVER SIDE REAR SEAT CUSHION BLOWER CIRCUITS FOR AN OPEN

- Measure the resistance between:
- PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365C-16, circuit CHS67 (VT/BN), harness side and driver seat cushion TED (Thermo-Electric Device) C3358-2, circuit CHS67 (VT/BN), harness side.

- PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365C-15, circuit RHS67 (WH/BU), harness side and driver seat cushion TED (Thermo-Electric Device) C3358-4, circuit RHS67 (WH/BU), harness side.

Are the resistances less than 5 ohms?

Yes
GO to BL13.

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

BL13 CHECK THE DRIVER SIDE REAR SEAT CUSHION 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 driver side rear seat cushion TED (Thermo-Electric Device) C3358 pin 2 and pin 4, component side.

Is the resistance between 4,000 ohms and 10,000 ohms?

Yes
GO to BL14.

No
INSTALL a new driver side rear seat cushion TED (Thermo-Electric Device). REFER to Seat Cushion Thermo-Electric Device - Second Row . CLEAR the DTCs. REPEAT the self-test.

BL14 CHECK THE DRIVER SIDE REAR SEAT CUSHION 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 driver side rear seat cushion TED (Thermo-Electric Device) C3358 pin 7 and pin 4, component side.

Is the resistance between 240K ohms and 400K ohms?

Yes
GO to BL15.

No
INSTALL a new driver side rear seat cushion TED (Thermo-Electric Device). REFER to Seat Cushion Thermo-Electric Device - Second Row . CLEAR the DTCs. REPEAT the self-test.

BL15 CHECK THE DRIVER SIDE REAR SEAT CUSHION TED (Thermo-Electric Device) INSTALLATION AND FOR CRUSHED SEAT CUSHION

- Ignition OFF.

- Remove the seat cushion cover. Refer to Seat Backrest Cover- Second Row, 40 Percent or Seat Backrest Cover- Second Row, 60 Percent .

- Inspect the seat cushion for the following:
- Is the seat cushion TED (Thermo-Electric Device) correctly installed?

- Is the seat cushion seat cushion foam pad crushed or restricted?

- Is the seat cushion climate controlled seat manifold crushed or restricted?

Is the driver side rear seat cushion TED (Thermo-Electric Device) correctly installed and are there no signs of damage to the foam pad and manifold?

Yes
INSTALL the driver side rear seat cushion cover and seat and GO to BL18.

No
CORRECTLY install the driver side rear seat cushion TED (Thermo-Electric Device) or INSTALL a new driver side rear seat cushion foam pad and/or climate controlled seat manifold. CLEAR the DTCs. REPEAT the self-test.

BL16 CHECK THE DRIVER SIDE REAR SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR AND WIRING

- Ignition OFF.

- Disconnect: PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365B.

- Measure the resistance between PCSM-2 (Passenger Climate Controlled Seat Module - 2) C3365B-7, circuit VHS42 (GN), harness side and C3365B-8 circuit RHS42 (BN/WH), 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 BL18.

No
GO to BL17.

BL17 CHECK THE DRIVER SIDE REAR SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR

- Measure the resistance between driver side rear seat cushion TED (Thermo-Electric Device) C3358 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 between 0.9 and 10 ohms?

Yes
GO to BL21.

No
GO to BL20.

BL20 CHECK THE RESISTANCE OF THE DRIVER SIDE REAR SEAT CUSHION TED (Thermo-Electric Device)

- Disconnect: Driver Side Rear Seat Cushion TED (Thermo-Electric Device) C3358.

- Measure the resistance between driver side rear seat cushion TED (Thermo-Electric Device) C3358 pin 1 and pin 3, component side.

Is the resistance between 0.9 and 10 ohms?

Yes
REPAIR circuit CHS39 (GN/BU) or RHS39 (VT/OG) for an open or high resistance. CLEAR the DTCs. REPEAT the self-test.

No
INSTALL a new driver side rear seat cushion TED (Thermo-Electric Device). REFER to Seat Cushion Thermo-Electric Device - Second Row . CLEAR the DTCs. REPEAT the self-test.

BL21 CHECK FOR CORRECT PCSM-2 (Passenger Climate Controlled Seat Module - 2) OPERATION

- Inspect the PCSM-2 (Passenger Climate Controlled Seat Module - 2) and driver side rear seat cushion 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 PCSM-2 (Passenger Climate Controlled Seat Module - 2), TED (Thermo-Electric Device) and Body Harness-to-Seat Harness Connectors.

- Make sure the connectors are seated correctly.

- Start the engine.

- Set the driver seat to OFF.

- Enter the following diagnostic mode on the scan tool: Clear DTCs - PCSM-2 (Passenger Climate Controlled Seat Module - 2).

- Attempt to recreate the fault. With the engine still running set the driver side rear seat to HIGH heat for at least 15 minutes.

Is the concern still present?

Yes
INSTALL a new PCSM-2 (Passenger Climate Controlled Seat Module - 2). REFER to Passenger Climate - Controlled Seat Module (PCSM-2) . REPEAT the self-test. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.