For 1990-2009 cars

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step determines if the vented seat system is totally inoperative.

2. This step determines which part of the seat is inoperative, the seat cushion or seat back.

3. This step tests the integrity of the pulse width modulation (PWM) serial data signal circuit from the memory seat module. This signal is a momentary 35 millisecond one-shot pulse signal that is displayed by a momentary change in the volt voltmeter when the switch is pressed. Placing the switch in the HIGH HEAT position first before pressing the vented seat switch, will display the greatest amount of change in the measured voltage. In addition, the voltmeter reading should be stable to accurately recognize the change in voltage.

4. This step determines if the seat cushion blower has an internal short to ground or voltage.

5. This step determines if the seat back blower has an internal short to ground or voltage.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Driver Seat Schematics and Passenger Seat Schematics Connector End View Reference: Component Connector End Views DEFINITION: This test assumes that Load Shed Level 1 or 2 is not Enabled.
1 | Did you review the vented seat operation and perform the necessary inspection? | -- | Go to Step 2 | Go to Symptoms - Seats
2 | Verify that the vented seat inoperative complaint is present. Does the vented seat system operate as described in the system description and operation? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3
3 | Are both the driver and front passenger vented seats inoperative? | -- | Go to Step 5 | Go to Step 4
4 | Are both the seat cushion and seat back inoperative? | -- | Go to Step 8 | Go to Step 17
5 |

1. Turn OFF the ignition.
2. Disconnect the climate control seat module connector C2.
3. Turn ON the ignition, with the engine OFF.
4. Measure the voltage from the ignition 3 voltage circuit of the climate control seat module to a good ground.

Does the voltage measure within the specified range?

10-15 V

Go to Step 6

Go to Step 30

6 | Measure the voltage from the ignition 3 voltage circuit of the climate control seat module to the ground circuit of the climate control seat module. Does the voltage measure within the specified range? | 10-15 V | Go to Step 7 | Go to Step 31
7 | Note: If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature.

1. Turn OFF the ignition.
2. Disconnect the climate control seat module connector C2.
3. Measure the resistance between the temperature sensor signal circuit and the temperature sensor low reference circuit of the climate control seat module connector.

Does the resistance measure within the specified range?

600 Ω - 1150 K Ω

Go to Step 25

Go to Step 35

8 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the appropriate Vented Seat parameter in the HVAC Control Module Non-HVAC Data list.
4. Press the suspect vented seat switch.

Does the Vented Seat parameter change state?

--

Go to Step 9

Go to Step 29

9 |

1. Place the appropriate heated/vented seat switch in the HIGH HEAT position.
2. Measure the voltage from the appropriate pulse width modulation (PWM) serial data signal circuit of the climate control seat module to a good ground.
3. Press the appropriate vented seat switch.

Does the measured voltage change state?

--

Go to Step 11

Go to Step 10

10 |

1. Turn OFF the ignition.
2. Disconnect the memory seat module (MSM) connector C4.
3. Turn ON the ignition, with the engine OFF.
4. Measure the voltage from the appropriate PWM serial data signal circuit of the MSM connector to a good ground.

Is the voltage measure near the specified value?

2.50 V

Go to Step 28

Go to Step 22

11 |

1. Turn the vented seat switch to the OFF position.
2. Measure the voltage from the fan speed control circuit of the seat cushion blower motor to a good ground.

Is the voltage measure near the specified value?

10 volts

Go to Step 14

Go to Step 12

12 |

1. Disconnect the seat cushion blower motor.
2. From the climate control seat module side of the connector, measure the voltage between the blower speed control circuit and a good ground.

Is the voltage measure near the specified value?

10 volts

Go to Step 27

Go to Step 13

13 |

1. Disconnect the seat back blower motor.
2. From the climate control seat module side of the connector, measure the voltage between the blower speed control circuit and a good ground.

Is the voltage measure near the specified value?

10 volts

Go to Step 27

Go to Step 20

14 | Measure the voltage from the battery voltage circuit of the blower motor connector to a good ground. Does the voltage measure within the specified range? | 10-15 V | Go to Step 15 | Go to Step 32
15 | Measure the voltage between the battery voltage circuit of the blower motor connector and the ground circuit of the motor connector. Does the voltage measure within the specified range? | 10-15 V | Go to Step 16 | Go to Step 33
16 | Note: If the resistance is measured with the seat still warm, the resistance may vary outside of the specified range since the thermistor resistance varies with temperature. Measure the resistance between the temperature sensor signal circuit and the temperature sensor low reference circuit of the climate control seat module connector.

Does the resistance measure within the specified range?

600 Ω - 1150 K Ω

Go to Step 21

Go to Step 23

17 |

1. Turn OFF the ignition.
2. Disconnect the inoperative seat blower motor.
3. Turn ON the ignition, with the engine OFF.
4. Measure the voltage from the battery voltage circuit of the blower motor connector to a good ground.

Does the voltage measure within the specified range?

10-15 V

Go to Step 18

Go to Step 32

18 | Measure the voltage between the battery positive voltage circuit of the blower motor connector and the ground circuit of the blower motor connector. Does the voltage measure within the specified range? | 10-15 V | Go to Step 19 | Go to Step 33
19 | From the climate control seat module side of the connector, measure the voltage between the blower speed control circuit and a good ground. Is the voltage measure near the specified value? | 10 V | Go to Step 27 | Go to Step 34
20 | Test the control circuit of the seat blower motors for the following conditions: Refer to Circuit Testing and Wiring Repairs.

• | An open circuit

• | Short to ground

• | Short to battery voltage

Did you find and correct the condition?

--

Go to Step 41

Go to Step 25

21 | Test the temperature sensor signal circuit between the climate control seat module and the temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 25
22 | Test the PWM serial data signal circuit between the memory seat module and the climate control seat module for the following conditions. Refer to Circuit Testing and Wiring Repairs.

• | An open circuit

• | A short to ground

• | A short to B+

Did you find and correct the condition?

--

Go to Step 41

Go to Step 25

23 | Test the signal circuit of the heated/vented seat temperature sensor for a short to voltage and an open. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 24
24 | Test the low reference circuit of the heated/vented seat temperature sensor for an open. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 26
25 | Inspect for poor connections at the harness connector of the climate control seat module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 36
26 | Inspect for poor connections at the harness connector of the seat cushion heating element and temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 37
27 | Inspect for poor connections at the harness connector of the inoperative seat blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 38
28 | Inspect for poor connections at the harness connector of the MSM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 39
29 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 41 | Go to Step 40
30 | Repair the short to ground or open in the ignition 3 voltage circuit of the climate control seat module. Refer to Wiring Repairs. Is the trouble corrected? | -- | Go to Step 41 | --
31 | Repair the open in the ground circuit of the climate control seat module. Refer to Wiring Repairs. Is the trouble corrected? | -- | Go to Step 41 | --
32 | Repair the short to ground or open in the battery voltage circuit of the seat blower motor. Refer to Wiring Repairs. Is the trouble corrected? | -- | Go to Step 41 | --
33 | Repair the open in the ground circuit of the seat blower motor. Refer to Wiring Repairs. Is the trouble corrected? | -- | Go to Step 41 | --
34 | Repair the open in the control circuit of the seat blower motors. Refer to Wiring Repairs. Is the trouble corrected? | -- | Go to Step 41 | --
35 | Repair the open in the low reference circuit of the heated/vented seat temperature sensors. Refer to Wiring Repairs. Is the trouble corrected? | -- | Go to Step 41 | --
36 | Replace the climate control seat module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | -- | Go to Step 41 | --
37 | Replace the seat cushion heating element/temperature sensor. Refer to Driver or Passenger Seat Back Ventilation Heating and Cooling Blower Replacement. Have you finished the replacement? | -- | Go to Step 41 | --
38 | Replace the seat blower motor motor. Refer to Driver or Passenger Seat Back Ventilation Heating and Cooling Blower Replacement. Have you finished the replacement? | -- | Go to Step 41 | --
39 | Replace the MSM. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | -- | Go to Step 41 | --
40 | Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | -- | Go to Step 41 | --
41 | Operate the system to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2