GM Service Manual Online
For 1990-2009 cars only

Test Description

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

  1. This step tests the integrity of the heated seat back only mode signal from the door module. This signal is a momentary 35 millisecond one shot pulse signal that is monitored through a momentary change in voltage when the switch is pressed. In order to accurately recognize the change in voltage, the volt meter should be stable before performing this test.

Step

Action

Value(s)

Yes

No

Schematic Reference: Heated Seats Schematics

1

Did you perform the Diagnostic System Check - Power Seat Systems?

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Go to Step  2

Go to Diagnostic System Check - Power Seat Systems

2

Verify that the Heated Seat Inoperative - Heated Back Mode complaint is present.

Does the heated seat back only mode operate as described in the Heated Seats Description and Operation?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Heated Seat Mode parameter in the Door Module data list.
  4. With the heated seat ON, activate the heated seat BACK ONLY switch.

Does the Heated Seat Mode parameter change state?

--

Go to Step  5

Go to Step  4

4

  1. Probe the heated seat back only mode switch terminal of the heated seat switch with a test lamp that is connected to a good ground.
  2. With the heated seat ON, activate the heated seat BACK ONLY switch.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step  12

5

  1. Measure the voltage from the heated seat back only mode signal circuit of the heated seat module to a good ground.
  2. Operate the heated seat BACK ONLY switch.

Does the measured voltage momentarily change state?

--

Go to Step  10

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Disconnect the door module connector C3.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the heated seat back only mode signal circuit of the door module connector to a good ground.

Does the voltage measure within the specified range?

4.50-5.50 V

Go to Step  11

Go to Step  8

7

Test the heated seat back only mode switch signal circuit between the heated seat switch and the door module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 11

8

Test the heated seat back only mode signal circuit between the door module and the heated seat module for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 9

9

Test the heated seat back only mode signal circuit between the door module and the heated seat module for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 10

10

Inspect for poor connections at the harness connector of the heated seat module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

11

Inspect for poor connections at the harness connector of the door control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

12

Inspect for poor connections at the harness connector of the heated seat switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

13

Replace the heated seat module. Refer to Front Seat Heater Control Module Replacement or Rear Seat Heater Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

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14

Replace the door control module. Refer to Door Control Module Replacement in Doors.

Did you complete the replacement?

--

Go to Step 16

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15

Replace the heated seat switch. Refer to Front Seat Heater Switch Replacement or Rear Seat Heater Switch Replacement .

Did you complete the replacement?

--

Go to Step 16

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16

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2