AM18-AM34

Seats

Pinpoint Tests

Pinpoint Test AM: DTC B272C

Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number

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, diagnostic testing can be carried out with the ignition Key ON Engine OFF (KOEO). The system receives voltage from Battery Junction Box (BJB) fuse 12 (30A) supplying battery voltage on circuit SBB12 (GN/RD) into DCSM C3305a pin F. The system also receives voltage from BJB fuse 11 (30A) supplying battery voltage on circuit SBB11 (BU/RD) into DCSM C3305a pin E. If voltage is disconnected from either pin E or F of DCSM C3305a with the voltage connection remaining on the other circuit, both seats will remain operational because the voltage supply 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.

The 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, the 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 HVAC module seat switch settings.

A differential fault occurs when the cushion and backrest TEDs on an affected seat are reporting very different temperatures to the DCSM. This may result from an airflow restriction or a circuit fault of either TED area. If a TED and manifold is clear of obstruction and is operational, the other TED and circuitry on the seat should be checked. It is important to note that a TED with a higher temperature may be operating correctly and not the area of concern. The other TED may be indicating a much lower temperature, causing the DTC to set.

- DTC B272C Driver Differential Temperature Fault - If there is a temperature differential between the driver backrest and cushion TED of 60°C (108°F) or more for more than 4 seconds, the TED is disconnected or the duct is blocked, this DTC will set. When this happens the first time in a key cycle, the DCSM puts the driver seat system into recovery mode (see principles of operation). If the system is able to recover, it will function normally. If the system is able to recover and it occurs a second time in the same key cycle, the DCSM will shut down the driver seat system.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Restricted cushion or backrest TED filter
- Crushed or restricted cushion or backrest foam pad
- Crushed or restricted cushion or backrest climate controlled seat manifold
- Cushion or backrest TED assembly
- DCSM

PINPOINT TEST AM: DTC B272C

NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition switch is ON.

NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.

-------------------------------------------------
AM18 CHECK TED THERMISTOR AND WIRING RESISTANCE AT THE DCSM

- Measure resistance between DCSM C3305b-7, circuit VHS26 (VT), harness side and DCSM C3305b-8, circuit RHS05 (YE/VT), harness side. Note the ambient temperature and compare result to the following table:

- Is resistance within the limits indicated?

Yes
INSTALL a new DCSM and CARRY OUT Programmable Module Installation (PMI). REFER to Dual Climate Controlled Seat Module (DCSM) Dual Climate Controlled Seat Module (DCSM). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
GO to AM19.

-------------------------------------------------
AM19 CHECK TED THERMISTOR RESISTANCE

- Disconnect: Cushion TED C3300.
- Measure resistance between cushion TED pin 5 and pin 8, component side. Note the ambient temperature and compare result to the following table:

- Is resistance within the limits indicated?

Yes
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM20 CHECK FOR CORRECT TED INSTALLATION AND FOR CRUSHED FOAM

- Ignition OFF.
- Remove the seat. Refer to Seat - Front Seat - Front.
- Remove the seat backrest trim cover. Refer to Seat Backrest Cover - Front, Without Fold Flat Seat Backrest Cover - Front, Without Fold Flat.
- Inspect the seat backrest for the following:
- Is the backrest blower obstructed?
- Is the blower filter restricted or plugged?
- Is the TED correctly installed?
- Is the seat backrest foam pad crushed or restricted?
- Is the climate controlled seat manifold crushed or restricted?
- Is the TED correctly installed and the foam pad and manifold OK?

Yes
GO to AM21.

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

DISCONNECT the battery ground cable. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM21 CHECK CUSHION TED CIRCUIT RHS02 (BU/OG) FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Position the driver seat in the vehicle and connect the seat-to-floor connectors.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Air Bag Systems.
- Disconnect: Driver Seat Side Air Bag C327.
- Disconnect: Passenger Seat Side Air Bag Module C313.
- Disconnect: DCSM C3305a.
- 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.
- Ignition ON.
- Measure voltage between DCSM C3305a-H, circuit RHS02 (BU/OG), harness side and ground.

- Is resistance greater than 10,000 ohms?

Yes
GO to AM23.

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

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM23 CHECK RESISTANCE OF THE CUSHION TED AND WIRING

- Measure resistance between DCSM C3305a-G circuit CHS02 (YE/BU), harness side and DCSM C3305a-H, circuit RHS02 (BU/OG), harness side.

- Is resistance between 0.9 and 10 ohms?

Yes
GO to AM25.

No
GO to AM24.

-------------------------------------------------
AM24 CHECK CUSHION TED RESISTANCE

- Disconnect: Cushion TED C3300.
- Measure resistance between cushion TED C3300 pin 1 and pin 3, component side.

- Is resistance between 0.9 and 10 ohms?

Yes
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
INSTALL a new cushion TED. REFER to Seat Cushion Thermo-Electric Device Seat Cushion Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM25 CHECK BLOWER CIRCUIT CHS03 (GN/BN) AND SPEED CONTROL CIRCUIT VHS16 (BU/GN) FOR A SHORT TO VOLTAGE

- Disconnect: DCSM C3305c.
- Ignition ON.
- Measure voltage between:
- DCSM C3305c-16, circuit CHS03 (GN/BN), harness side and ground.
- DCSM C3305c-12, circuit VHS16 (BU/GN), harness side and ground.

- Is voltage present on either circuit?

Yes
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
GO to AM26.

-------------------------------------------------
AM26 CHECK BLOWER AND SPEED CONTROL CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.
- Measure resistance between:
- DCSM C3305c-16, circuit CHS03 (GN/BN), harness side and ground.
- DCSM C3305c-12, circuit VHS16 (BU/GN), harness side and ground.

- Are resistances greater than 10,000 ohms?

Yes
GO to AM27.

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

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM27 CHECK BLOWER AND WIRING RESISTANCE

- NOTE: The ohmmeter must be connected with the positive lead to DCSM C3305c-16, circuit CHS03 (GN/BN) and the negative lead to DCSM C3305c-15, circuit RHS03 (GY/OG) when measuring. Ohmmeter leads incorrectly connected will result in false readings and lead to incorrect identification of components that are not faulty.
- Measure resistance between DCSM C3305c-16, circuit CHS03 (GN/BN), harness side and DCSM C3305c-15, circuit RHS03 (GY/OG), harness side.

- Is resistance between 6K ohms and 9K ohms?

Yes
GO to AM29.

No
GO to AM28.

-------------------------------------------------
AM28 CHECK BLOWER RESISTANCE

- Disconnect: Backrest TED C3310.
- 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 resistance between backrest TED C3310 pin 2 and pin 4, component side.

- Is resistance between 6K ohms and 9K ohms?

Yes
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM29 CHECK BLOWER SPEED CONTROL AND CIRCUIT RESISTANCE

- NOTE: The ohmmeter must be connected with the positive lead to C3305c-12, circuit VHS16 (BU/GN), harness side and the negative lead to C3305c-15, circuit RHS03 (GY/OG), harness side when measuring. Ohmmeter leads incorrectly connected will result in false readings and lead to incorrect identification of components that are not faulty.
- Measure resistance between DCSM C3305c-12, circuit VHS16 (BU/GN) harness side and DCSM C3305c-15, circuit RHS03 (GY/OG), harness side.

- Is resistance between 290K ohms and 420K ohms?

Yes
GO to AM31.

No
GO to AM30.

-------------------------------------------------
AM30 CHECK BLOWER SPEED CONTROL RESISTANCE

- Disconnect: Backrest TED C3310.
- 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 resistance between backrest TED C3310 pin 7 and pin 4, component side.

- Is resistance between 290K ohms and 420K ohms?

Yes
REPAIR the circuit(s). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
INSTALL a new backrest TED. REFER to Seat Backrest Thermo-Electric Device Seat Backrest Thermo-Electric Device. REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM31 CHECK THERMISTOR CIRCUIT FOR A SHORT TO VOLTAGE

- Disconnect: DCSM C3305b.
- Ignition ON.
- Measure voltage between DCSM C3305b-9, circuit VHS35 (VT/OG), 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 driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
GO to AM32.

-------------------------------------------------
AM32 CHECK THERMISTOR CIRCUIT 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: Driver Seat Side Air Bag Module C327.
- Disconnect: Passenger Seat Side Air Bag Module C313.
- Disconnect: DCSM C3305b.
- Measure resistance between DCSM C3305b-9, circuit VHS35 (VT/OG), harness side and ground.

- Is resistance greater than 10,000 ohms?

Yes
GO to AM33.

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

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

-------------------------------------------------
AM33 CHECK TED THERMISTOR AND WIRING RESISTANCE

- Measure resistance between DCSM C3305b-9, circuit VHS35 (VT/OG), harness side and DCSM C3305b-10, circuit RHS15 (GY/BN), harness side. Note the ambient temperature and compare result to the following table:

- Is resistance within the limits indicated?

Yes
INSTALL a new DCSM and CARRY OUT Programmable Module Installation (PMI). REFER to Dual Climate Controlled Seat Module (DCSM) Dual Climate Controlled Seat Module (DCSM). REPEAT the self-test. CLEAR the DTCs.

DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C327. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Air Bag Systems.

No
GO to AM34.

-------------------------------------------------
AM34 CHECK TED THERMISTOR RESISTANCE

- Disconnect: Backrest TED C3310.
- Measure resistance between backrest TED pin 5 and pin 8, component side. Note the ambient temperature and compare result to the following table: