GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 CTS 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Rear Window Defogger Inoperative

Test Description

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

  1. If Load Shed Lvl.2 R. Defog. data parameter is displayed as Enabled, system voltage may be low due to number of loads enabled on the vehicle, while the ignition is ON. This may be normal due to the number of loads enabled or the vehicle may have a charging system or battery concern.

    2.

  2. Gain access to the RR DEFOG relay and listen for an audible click when the relay operates. Command both the ON and OFF states of the RR DEFOG relay. Repeat the commands as necessary.

Step

Action

Yes

No

Schematic Reference: Defogger Schematics

Connector End View Reference: Window Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn ON the ignition, with the engine OFF.
  2. Depress the rear window defogger switch.
  3. Observe the rear window defogger indicator on the HVAC control module.

Does the rear window defogger indicator illuminate?

Go to Step 3

Go to Step 5

3

Connect a test lamp between the rear window defogger grid and ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 7

4

Connect a test lamp between the left side of the rear window defogger grid and the right side of the rear window defogger grid.

Does the test lamp illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 17

5

With a scan tool, observe the Rear Defog Relay data parameter in the rear integration module (RIM) data list.

Does the scan tool display ON?

Go to Step 6

Go to Step 14

6

With a scan tool, observe the Load Shed Lvl. 2 R. Defog. data parameter in the RIM data list.

Does the scan tool display Enabled?

Go to Diagnostic System Check - Vehicle

Go to Step 14

7

  1. Select from the special functions, the Rear Defog Relay from the RIM output controls.
  2. With a scan tool, command the RR DEFOG relay ON and OFF.

Do you hear a click when you command the RR DEFOG relay ON and OFF?

Go to Step 10

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the RR DEFOG relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the ignition voltage circuit of the RR DEFOG relay coil and ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 18

9
  1. Connect a test lamp between the control circuit of the RR DEFOG relay and the ignition voltage circuit of the RR DEFOG relay coil.
  2. With a scan tool, command the RR DEFOG relay ON.

Does the test lamp illuminate?

Go to Step 15

Go to Step 12

10
  1. Turn OFF the ignition.
  2. Disconnect the RR DEFOG relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the RR DEFOG relay switched input and a good ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 13

11
  1. Connect a 40-amp fused jumper between the battery positive voltage circuit of the RR DEFOG relay switched input and the relay switched output to the supply voltage circuit of the rear window defogger.
  2. Connect a test lamp between the rear window defogger grid and ground.

Does the test lamp illuminate?

Go to Step 15

Go to Step 20

12

Test the control circuit of the RR DEFOG relay for an open or short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 24

Go to Step 16

13

Test the battery positive voltage circuit of the RR DEFOG relay switched input for an open or high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 24

Go to Step 19

14

Inspect for a poor connection at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 24

Go to Step 21

15

Inspect for a poor connection at the RR DEFOG relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 24

Go to Step 22

16

Inspect for a poor connection at the harness connector of the RIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 24

Go to Step 23

17

Repair an open or high resistance in the ground circuit of the rear window defogger. Refer to Wiring Repairs.

Did you complete the repair?

Go to Step 24

--

18

Repair an open or a high resistance in the ignition voltage circuit of the RR DEFOG relay coil. Refer to Wiring Repairs.

Did you complete the repair?

Go to Step 24

--

19

Repair a short to ground in the supply voltage circuit of the rear window defogger. Refer to Wiring Repairs.

Did you complete the repair?

Go to Step 24

--

20

Repair an open or high resistance in the supply voltage circuit of the rear window defogger. Refer to Wiring Repairs.

Did you complete the repair?

Go to Step 24

--

21

Replace the HVAC control module. Refer to HVAC Control Module Replacement.

Did you complete the replacement?

Go to Step 24

--

22

Replace the RR DEFOG relay. Refer to Relay Replacement.

Did you complete the replacement?

Go to Step 24

--

23

Replace the RIM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 24

--

24

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2