GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Body and Accessories 🢒 Seats 🢒 Heated Seat Inoperative

Step

Action

Value(s)

Yes

No

1

Inspect the DIC/HVAC fuse.

Is the DIC/HVAC fuse open?

--

Go to Step 2

Go to Step 3

2
  1. Repair a short to ground in CKT 541.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 3

System OK

3
  • Inspect HSEAT/LUM fuse.

Is the HSEAT/LUM fuse open?

--

Go to Step 4

Go to Step 5

4
  1. Repair a short to ground in CKT 2040.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 5

System OK

5
  1. Connect a test lamp.
  2. Backprobe between the driver seat heater control module connector terminal D and ground.

Does the test lamp light?

--

Go to Step 6

Go to Step 12

6
  1. Connect a test lamp.
  2. Backprobe between the driver seat heater control module connector terminals D and F.

Does the test lamp light?

--

Go to Step 7

Go to Step 13

7
  1. Turn the ignition switch to the RUN position.
  2. Connect a test lamp.
  3. Backprobe between the driver seat heater control module connector terminal C and ground.
  4. Set the heated driver seat switch to the HI and then the LO positions.

Does the test lamp light with the switch in both positions?

--

Go to Step 8

Go to Step 14

8
  1. Turn the ignition switch to the RUN position.
  2. Connect a test lamp.
  3. Backprobe between the driver seat heater control module connector terminal B and ground.
  4. Set the heated driver seat switch to the HI and then the LO positions.

Does the test lamp light with the switch in both positions?

--

Go to Step 9

Go to Step 20

9
  1. Turn the ignition switch to the OFF position.
  2. Ensure the heated driver seat switch is not set to HI or LO.
  3. Disconnect the driver seat heater control module connector.
  4. Measure the resistance between the driver seat heater control module connector terminal A and ground.

Is the resistance within the specified range?

0-2.0ohms

Go to Step 10

Go to Step 23

10
  • Measure the resistance between the driver seat heater control module connector terminal E and ground.

Is the resistance within the specified values?

3000-5000ohms

Go to Step 11

Go to Step 28

11
  1. Replace the driver seat heater control module. Refer to Heater Module Replacement .
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 12

System OK

12
  1. Repair the poor connection or open in CKT 2040.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 13

System OK

13
  1. Repair the poor connection or open in CKT 750 to G301.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 14

System OK

14

Observe the test lamp.

Does the test lamp light in either position?

--

Go to Step 23

Go to Step 15

15
  1. Turn the ignition switch to the RUN position.
  2. Connect a test lamp.
  3. Backprobe between the driver seat heater switch connector terminal D and ground.

Does the test lamp light?

--

Go to Step 17

Go to Step 16

16
  1. Repair the poor connection or open in CKT 541.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 17

System OK

17

Inspect for a poor connection or open in CKT 1462.

Is there a poor connection or open in CKT 1462?

--

Go to Step 18

Go to Step 19

18
  1. Repair the poor connection or open in CKT 1462.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 19

System OK

19
  1. Replace the driver seat heater switch. Refer to Heater Module Replacement .
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 20

System OK

20

Observe the test lamp.

Does the test lamp light in either position?

--

Go to Step 19

Go to Step 21

21

Inspect for a poor connection or open in CKT 1501.

Is there a poor connection or open in CKT 1501?

--

Go to Step 22

Go to Step 19

22
  1. Repair the poor connection or open in CKT 1501.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 23

System OK

23
  1. Disconnect the driver seat cushion cover connector.
  2. Measure the resistance between the driver seat cushion cover connector terminals A and B.

Is the resistance within the specified range?

0-1.0ohms

Go to Step 24

Go to Step 27

24
  1. Disconnect the driver seat back cushion cover connector.
  2. Measure the resistance between the driver seat cushion cover connector terminals A and B.

Is the resistance within the specified range?

0-1.0ohms

Go to Step 25

Go to Step 26

25
  1. Repair the poor connection or open in CKTs 900, 950 or 750 between the driver seat heater control module harness connector terminal A and S330.
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 26

System OK

26
  1. Replace the heated seat element in the driver seat cushion cover. Refer to Heater Module Replacement .
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 27

System OK

27
  1. Replace the heated seat element in the driver seat back cushion cover. Refer to Heater Module Replacement .
  2. Inspect the system.

Is the symptom still present?

--

Go to Step 28

System OK

28
  1. Disconnect the driver seat cushion cover connector.
  2. Measure the resistance between the driver seat cushion cover connector terminals C and D.

Is the resistance within the specified range?

3000-5000ohms

Go to Step 29

Go to Step 30

29
  1. Repair the poor connection or open in CKT 952 or CKT 750 to S330.
  2. Inspect the system.

Is the symptom still present?

--

--

System OK

30
  1. Replace the heated seat thermistor in the driver seat cushion cover. Refer to Front Seat Cushion Replacement .
  2. Inspect the system.

Is the symptom still present?

--

--

System OK