Rear Blower Motor Inoperative

REAR BLOWER MOTOR INOPERATIVE





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.






1. CHECK FOR CCN DTCS
1. With a scan tool, check for Cluster or Cabin Compartment Node (CCN) DTCs.

Are there any DTCs present?

Yes

- Testing and Inspection and perform the appropriate diagnostic procedure.

No

- Go To 2

2. CHECK THE REAR BLOWER MOTOR RELAY
1. Ignition on, engine not running.
2. Press the Rear HVAC button On and Off several times while listening to or feeling the Rear Blower Motor relay click.

Do you hear or feel the Rear Blower Motor relay click when the Rear HVAC is pressed On and Off?

Yes

- Go To 3

No

- Go To 11

3. CHECK REAR BLOWER MOTOR OPERATION WITH A SUBSTITUTE RELAY INSTALLED
1. Install a substitute relay in place of the existing Rear Blower Motor Relay.
2. Ignition on, engine not running.
3. Press the Rear HVAC button on the upper switch bank to On.
4. Using the rear controls, turn the rear blower to high.

Does the rear blower motor operate properly?

Yes

- Replace the original Rear Blower Motor Relay.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. CHECK THE (A611) FUSED B(+) CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Remove the Rear Blower Motor Relay.
3. Ignition on, engine not running.
4. Using a 12-volt test light connected to ground, check the (A611) Fused B(+) circuit in the Rear Blower Motor Relay connector.

NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Repair the (A611) Fused B(+) circuit for an open or short to ground.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. CHECK THE (C51) REAR BLOWER MOTOR RELAY OUTPUT CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Reinstall the Rear Blower Motor Relay.
3. Ignition on, engine not running.
4. Press the Rear HVAC button on the upper switch bank to On.
5. Using a 12-volt test light connected to ground, back probe the (C51) Blower Motor Relay Output circuit in the Rear Blower Motor harness connector.

Does the test light illuminate brightly?

Yes

- Go To 6

No

- Repair the (C51) Blower Motor Relay Output circuit for an open or short to ground.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

6. CHECK REAR BLOWER MOTOR




1. Turn the ignition off.
2. Using a suitable jumper wire, backprobe between ground and the (C951) Rear Blower Speed Control circuit in the Rear Blower Motor harness connector.
3. Ignition on, engine not running.
4. Press the Rear HVAC button on the upper switch bank to On.

Does the rear blower motor run at high speed?

Yes

- Go To 7

No

- Replace the Rear Blower Motor.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

7. CHECK THE (C951) REAR BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Remove the jumper wire in the Rear Blower Motor harness connector
3. Disconnect the Rear Blower Motor Resistor harness connector.
4. Connect a jumper wire between ground and the (C951) Rear Blower Speed Control circuit in the Rear Blower Motor Resistor harness connector.
5. Ignition on, engine not running.
6. Press the Rear HVAC button on the upper switch bank to On.

Does the rear blower motor run at high speed?

Yes

- Go To 8

No

- Repair the (C951) Rear Blower Speed Control circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

8. CHECK THE (C153) REAR BLOWER HIGH SPEED CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Disconnect the Rear A/C Heater Control C2 harness connector.
3. Measure the resistance of the (C153) Rear Blower Speed Control circuit between the Rear Blower Motor Resistor Block harness connector and the Rear A/C Heater Control C2 harness connector.

Is the resistance below 100k Ohms?

Yes

- Go To 9

No

- Repair the (C153) Rear Blower High Speed circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

9. CHECK THE REAR BLOWER MOTOR RESISTOR FOR AN OPEN




1. Turn the ignition off.
2. Reconnect the Rear Blower Motor Resistor Block harness connector.
3. Connect a jumper wire between ground and the (C153) Rear Blower Motor High Speed Control circuit in the Rear A/C Heater Control C2 harness connector.
4. Ignition on, engine not running.
5. Press the Rear HVAC button on the upper switch bank to On.

Does the rear blower motor run at high speed?

Yes

- Go To 10

No

- Replace the Rear Blower Motor Resistor.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

10. CHECK THE (Z908) GROUND CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Connect a jumper wire between the (C153) Rear Blower Motor High Speed Control circuit and the (Z908) Ground circuit in the Rear A/C Heater Control C2 harness connector.
3. Ignition on, engine not running.
4. Press the Rear HVAC button on the upper switch bank to On.

Does the rear blower motor run at high speed?

Yes

- Replace the Rear A/C Heater Control.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the (Z908) Ground circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

11. CHECK THE (A611) FUSED B(+) CIRCUIT FUSE FOR AN OPEN
1. Turn the ignition off.
2. In the Power Distribution Center, check the fuse for the A611 Fused B(+) circuit for an open.

Is the fuse open?

Yes

- Replace the fuse. Note: If the fuse opens again during verification, make sure to check for a short to ground or a high amperage draw from the rear blower motor circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 12

12. CHECK REAR BLOWER MOTOR OPERATION WITH A SUBSTITUTE RELAY INSTALLED
1. Turn the ignition off.
2. Install a substitute relay in place of the existing Rear Blower Motor Relay.
3. Ignition on, engine not running.
4. Press the Rear HVAC button on the upper switch bank to On.
5. Turn the rear blower on high.

Does the rear blower motor operate properly?

Yes

- Replace the original Rear Blower Motor Relay.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 13

13. CHECK THE (A611) FUSED B(+) CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Remove the substitute Rear Blower Motor Relay.
3. Ignition on, engine not running.
4. Using a 12-volt test light connected to ground, check both of the (A611) Fused B(+) circuits in the Rear Blower Motor Relay connector.

NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 14

No

- Repair the (A611) Fused B(+) circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

14. CHECK THE (C105) HVAC MUX CONTROL CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Reinstall the Rear Blower Motor Relay.
3. Disconnect the Cluster C2 harness connector.
4. Connect a jumper wire between ground and the (C105) HVAC MUX Control circuit in the Cluster C2 harness connector.
5. Ignition on, engine not running.
6. Turn the rear blower on high.

Is the rear blower motor working?

Yes

- Replace the Cluster.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the (C105) HVAC MUX Control circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.