GM Service Manual Online
For 1990-2009 cars only

Test Description

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

  1. Listen for an audible click when the auxiliary blower motor relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

  2. Tests for voltage at the coil side of the auxiliary blower motor relay. The RR BLO fuse supplies power to the coil side of the auxiliary blower motor relay.

  3. Verifies that the rear integration module (RIM) is providing ground to the auxiliary blower motor relay.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The auxiliary blower motor is inoperative in all speed positions.

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the front blower motor switch in the maximum speed position.
  3. Place the front mode switch in the vent position.
  4. Place the auxiliary blower motor switch in each speed position.

Does the auxiliary blower motor operate in any speed position?

Go to Auxiliary Blower Motor Malfunction

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the auxiliary blower motor relay ON and OFF.

Does the auxiliary blower motor relay turn ON and OFF with each command?

Go to Step 9

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the auxiliary blower motor relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 3 voltage circuit of the auxiliary blower motor relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 15

5

  1. Connect a test lamp between the control circuit of the auxiliary blower motor relay and the ignition 3 voltage circuit of the auxiliary blower motor relay.
  2. With a scan tool, command the auxiliary blower motor relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 17

Go to Step 6

6

Does the test lamp remain illuminated with each command?

Go to Step 8

Go to Step 7

7

Test the control circuit of the auxiliary blower motor relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 19

8

Test the control circuit of the auxiliary blower motor relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 19

9

  1. Turn OFF the ignition.
  2. Disconnect the auxiliary blower motor.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the auxiliary blower motor supply voltage circuit and the high speed blower motor control circuit.
  5. Place the auxiliary blower motor control in the maximum speed position.

Does the test lamp illuminate?

Go to Step 18

Go to Step 10

10

Connect a test lamp between the auxiliary blower motor supply voltage circuit and ground.

Does the test lamp light?

Go to Step 13

Go to Step 11

11

Test the battery positive voltage circuit of the auxiliary blower motor for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in wiring systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 12

12

Test the battery positive voltage circuit of the auxiliary blower motor relay for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in wiring systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 17

13

Test the high speed blower motor control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in wiring systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 14

14

Test the ground circuit of the auxiliary HVAC control assembly for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 16

15

Repair the ignition 3 voltage circuit of the auxiliary blower motor relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 24

--

16

Inspect for poor connections at the auxiliary HVAC control assembly. 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 24

Go to Step 20

17

Inspect for poor connections at the auxiliary blower motor relay. 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 24

Go to Step 21

18

Inspect for poor connections at the auxiliary blower motor. 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 24

Go to Step 22

19

Inspect for poor connections at the harness connector of the rear integration module (RIM). 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 24

Go to Step 23

20

Replace the auxiliary HVAC control assembly. Refer to Auxiliary Heater and Air Conditioning Control Module Replacement .

Did you complete the replacement?

Go to Step 24

--

21

Replace the auxiliary blower motor relay.

Did you complete the replacement?

Go to Step 24

--

22

Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 24

--

23

Important: Perform the set up procedure for the rear integration module (RIM).

Replace the rear integration module (RIM). Refer to Rear Integration Body Control Module Replacement in Body Control System.

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