GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION:

    • The rear auxiliary blower motor will not operate.
    • Vehicle is equipped with heat only (C36).

1

Did you review the HVAC blower operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms

2

  1. Place the ignition switch in the RUN position.
  2. Place the auxiliary blower motor switch in the LOW position.

Does the blower motor operate?

--

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

Go to Step 3

3

  1. Disconnect the auxiliary blower motor low speed relay.
  2. Connect a J 35616-200 unpowered test lamp between auxiliary blower motor low speed relay connector cavity C1 for CKT 1542 (RED) and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 9

4

Connect a J 35616-200 unpowered test lamp between the auxiliary blower motor low speed relay connector cavity C2 for CKT 341 (BRN) and ground.

Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 10

5

  1. Disconnect the auxiliary blower motor switch.
  2. Connect a J 39200 digital multimeter (DMM) between auxiliary blower motor switch connector cavity B for CKT 150 (BLK), and ground. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 6

Go to Step 11

6

  1. Connect a J 39200 DMM between auxiliary blower motor switch pin E and pin B. Refer to Circuit Testing in Wiring Systems.
  2. Place the auxiliary blower motor switch in the MED position.

Is continuity present?

--

Go to Step 7

Go to Step 14

7

  1. Disconnect the auxiliary blower motor.
  2. Connect a J 39200 DMM between the auxiliary blower motor connector cavity A for CKT 150 (BLK) and ground. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 8

Go to Step 12

8

  1. Disconnect the auxiliary blower motor resistor.
  2. Connect a J 39200 DMM between the auxiliary blower motor resistor connector cavity D and the auxiliary blower motor connector cavity B for CKT 1172 (YEL). Refer to Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 15

Go to Step 13

9

Repair the open in CKT 1542 (RED) between the underhood fuse-relay center RR blower fuse, and splice S412.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

10

Repair the open in CKT 341 (BRN) between the instrument panel fuse block RR HVAC fuse and splice S405.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

11

Repair the open in CKT 150 (BLK) between the auxiliary blower motor switch connector, and ground G400.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

12

Repair the open in CKT 150 (BLK) between the auxiliary blower motor and ground G400.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Repair the open in CKT 1172 (YEL) between splice S413 and the auxiliary blower motor.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

14

Replace the auxiliary blower motor switch.

Refer to Control Assembly Replacement - Auxiliary .

Did you complete the repair?

--

Go to Step 16

--

15

Replace the auxiliary blower motor.

Refer to Auxiliary Blower Motor Replacement .

Did you complete the repair?

--

Go to Step 16

--

16

Operate the auxiliary blower motor in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3