Pinpoint Tests BM: DTC B272A
Seats
Pinpoint Test BM: DTC B272A
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
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 B272A (Passenger Cushion Over-Temp Detected) - For heat mode, if the passenger seat cushion TED temperature exceeds 110°C (230°F) continuously for more than 4 seconds in any heat mode, the DCSM turns off the TED and enters a fan only state to recover from the over-temperature condition (recovery mode). If the TED temperature does not recover after 30 seconds, the DTC will set and the seat is disabled. If the TED does recover, the TED 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 B272A (Passenger Cushion Over-Temp Detected) - For cool mode, if the passenger seat cushion TED temperature exceeds 65°C (149°F) continuously for more than 4 seconds in any cool mode, the DCSM turns off the TED and enters a fan only state to recover from the over-temperature condition (recovery mode). If the TED temperature does not recover after 5 minutes, the DTC will set and the seat is disabled. If the TED does recover, the TED 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 filter
- Crushed or restricted cushion foam pad
- Cushion TED assembly
- PCSM-2
PINPOINT TEST BM: DTC B272A
NOTICE: When taking measurements at Passenger Climate Controlled Seat Module - 2 (PCSM-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.
NOTE: 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.
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BM1 CHECK FOR PCSM-2 DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - PCSM-2.
- Was DTC B272A retrieved?
Yes
GO to BM2.
No
GO to BM4.
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BM2 CHECK CUSHION TED THERMISTOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCSM-2 C3365B.
- Disconnect: Cushion TED C3359.
- Measure the resistance between:
- PCSM-2 C3365B-2, circuit VHS45 (GY/BN), harness side and ground.
- PCSM-2 C3365B-3, circuit RHS45 (YE/GN), harness side and ground.
- Are the resistances greater than 10,000 ohms?
Yes
GO to BM3.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
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BM3 CHECK THE CUSHION TED THERMISTOR RESISTANCE
- Measure the resistance between cushion TED C3359 pin 5 and pin 8, component side. Note the ambient temperature and compare result to the following table:
- Is the resistance within the limits indicated?
Yes
REPAIR the open circuit(s). CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device - Second Row Seat Cushion Thermo-Electric Device - Second Row. CLEAR the DTCs. REPEAT the self-test.
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BM4 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 (part of foam pad) 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 RH 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 BM5.
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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BM5 CHECK OPERATION OF THE SEAT
- Ignition ON.
- With the engine running, set both seats to high cool (3 indicators illuminated).
- Compare the airflow from the RH seat cushion and compare it to the airflow from the LH seat cushion.
- Is the airflow exhausting from the RH seat cushion comparable to the airflow exhausting from the LH seat cushion?
Yes
GO to BM14.
No
GO to BM6.
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BM6 CHECK 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 clear of obstruction and filter clean?
Yes
GO to BM7.
No
REMOVE the obstruction or INSTALL a new filter. CLEAR the DTCs. REPEAT the self-test.
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BM7 CHECK CUSHION FAN OPERATION
- Ignition ON.
- With the engine running, set both seats to high cool (3 indicators illuminated).
- Inspect the cushion blower for operation.
- Does the cushion blower operate?
Yes
GO to BM14.
No
GO to BM8.
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BM8 CHECK BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: PCSM-2 C3365C.
- Disconnect: Cushion TED C3359.
- Measure the resistance between PCSM-2 C3365C-3, circuit VHS65 (VT/WH), harness side and cushion TED C3359-7, circuit VHS65 (VT/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to BM9.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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BM9 CHECK BLOWER CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between PCSM-2 C3365C-7, circuit RHS63 (WH/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
No
GO to BM10.
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BM10 CHECK BLOWER CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between PCSM-2 C3365C-8, circuit CHS63 (VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to BM11.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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BM11 CHECK BLOWER CIRCUITS FOR AN OPEN
- Measure the resistance between:
- PCSM-2 C3365C-8, circuit CHS63 (VT), harness side and cushion TED C3359-2, circuit CHS63 (VT), harness side.
- PCSM-2 C3365C-7, circuit RHS63 (WH/GN), harness side and cushion TED C3361-4, circuit RHS67 (WH/BU), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to BM12.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
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BM12 CHECK THE CUSHION 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 the resistance between cushion TED C3359 pin 2 and pin 4, component side.
- Is the resistance between 4,000 ohms and 10,000 ohms?
Yes
GO to BM13.
No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device - Second Row Seat Cushion Thermo-Electric Device - Second Row. CLEAR the DTCs. REPEAT the self-test.
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BM13 CHECK THE CUSHION 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 the resistance between cushion TED C3359 pin 7 and pin 4, component side.
- Is the resistance between 240K ohms and 4M ohms?
Yes
GO to BM14.
No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device - Second Row Seat Cushion Thermo-Electric Device - Second Row. CLEAR the DTCs. REPEAT the self-test.
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BM14 CHECK TED FOR CORRECT INSTALLATION AND FOR A CRUSHED SEAT CUSHION
- Ignition OFF.
- Remove the seat. Refer to Seat - Second Row Seat - Second Row.
- Remove the seat cushion trim cover. Refer to Seat Cushion Cover - Second Row, Bucket Seat Cushion Cover - Second Row, Bucket.
- Inspect the seat cushion for the following:
- Is the TED correctly installed?
- Is the seat cushion foam pad crushed or restricted?
- Is the TED correctly installed and foam pad OK?
Yes
INSTALL a new PCSM-2. REFER to Passenger Climate - Controlled Seat Module (PCSM-2) Passenger Climate - Controlled Seat Module (PCSM-2). CLEAR the DTCs. REPEAT the self-test.
No
CORRECTLY INSTALL the cushion TED or INSTALL a new seat cushion foam pad. CLEAR the DTCs. REPEAT the self-test.
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