Front Blower Motor Inoperative (ATC)

*FRONT BLOWER MOTOR INOPERATIVE (ATC)





For a complete wiring diagram Consult Diagrams/Electrical.





Diagnostic Test

1. CHECK PDC FUSE #1




Turn the ignition off.
Remove and inspect PDC Fuse #1.
Is the fuse open?

Yes

- Replace the fuse and Go To 2.

No

- Reinstall the fuse and Go To 7.

2. CHECK FRONT BLOWER MOTOR OPERATION
Turn the ignition on.
Turn the front blower on and operate it in all speeds.
Does the front blower motor operate properly without blowing the fuse?

Yes

- Check the (C7) Front Blower Motor Relay Output circuit and the (A502) Fused B(+) circuit for a condition causing an intermittent short to ground. Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 3

3. CHECK THE (C7) FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT & THE (A502) FUSED B(+) CIRCUIT FOR A SHORT TO THE (Z387) GROUND CIRCUIT




Turn the ignition off.
Remove the Front Blower Motor Relay from the PDC.
Disconnect the Front Blower Power Module C1 harness connector.
Measure the resistance between the (C7) Front Blower Motor Relay Output circuit and the (Z387) Ground circuit in the Front Blower Motor Relay connector.
Measure the resistance between the (A502) Fused B(+) circuit and the (Z387) Ground circuit in the Front Blower Motor Relay connector.
Is the resistance below 10K ohms on either circuit?

Yes

- Inspect the wiring harness for a condition causing the short between the (C7) Front Blower Motor Relay Output circuit / (A502) Fused B(+) circuit and the (Z387) Ground circuit and repair as necessary. If the inspection fails to produce the cause for the short, replace the PDC and replace the fuse.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 4

4. CHECK THE (C7) FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT & THE (A502) FUSED B(+) CIRCUIT FOR A SHORT TO GROUND




Measure the resistance of the (C7) Front Blower Motor Relay Output circuit between ground and the Front Blower Motor Relay connector.
Measure the resistance of the (A502) Fused B(+) circuit between ground and the Front Blower Motor Relay connector.
Is the resistance below 10K ohms on either circuit?

Yes

- Inspect the wiring harness for a condition causing the short between the (C7) Front Blower Motor Relay Output circuit / (A502) Fused B(+) circuit and ground and repair as necessary. If the inspection fails to produce the cause for the short, replace the PDC and replace the fuse.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 5

5. CHECK FRONT BLOWER MOTOR OPERATION WITH A SUBSTITUTE RELAY INSTALLED




Reconnect the Front Blower Power Module C1 harness connector.
Replace PDC Fuse #1.
Install a substitute relay in place of the existing Front Blower Motor Relay.
Turn the ignition on.
Turn the front blower on and operate it in all speeds.
Does the front blower motor operate properly without blowing the fuse?

Yes

- Replace the original Front Blower Motor Relay.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 6

6. CHECK FRONT BLOWER MOTOR OPERATION BY BYPASSING THE FRONT BLOWER POWER MODULE




Turn the ignition off.
Disconnect the Front Blower Power Module C1 harness connector.
Disconnect the Front Blower Power Module C2 harness connector.
Connect a jumper wire between the (C7) Front Blower Motor Relay Output circuit in the Front Blower Motor Power Module C1 harness connector and the (C7) Blower Motor Power circuit in the Front Blower Motor Power Module C2 harness connector.
Connect a jumper wire between the (Z134) Ground circuit in the Front Blower Motor Power Module C1 harness connector and the (C75) Blower Motor Ground circuit in the Front Blower Motor Power Module C2 harness connector.
Replace PDC Fuse #1.
Turn the ignition on.
Does the front blower motor run without blowing the fuse?

Yes

- Replace the Front Blower Motor Power Module. Reinstall the original Front Blower Motor Relay.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Replace the Front Blower Motor. Replace the fuse and reinstall the original Front Blower Motor Relay.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

7. CHECK JB FUSE #10




Remove and inspect JB Fuse #10.
Is the fuse open?

Yes

- Using the wiring schematics as a guide, check the (F921) Fused Run Relay Output circuit and the (C105) Rear HVAC Control circuit (if equipped) for a condition causing a short to ground. Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Reinstall the fuse and Go To 8.

8. CHECK FRONT BLOWER MOTOR OPERATION WITH A SUBSTITUTE RELAY INSTALLED




Install a substitute relay in place of the existing Front Blower Motor Relay in the PDC.
Turn the ignition on.
Turn the front blower on and operate it in all speeds.
Does the front blower motor operate properly?

Yes

- Replace the original Front Blower Motor Relay.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 9

9. CHECK THE (Z387) GROUND CIRCUIT FOR AN OPEN




Turn the ignition off.
Remove the substitute Front Blower Motor Relay.

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

Using a 12-volt test light connected to 12 volts, probe the (Z387) Ground circuit in the Front Blower Motor Relay connector.
Does the test light illuminate brightly?

Yes

- Go To 10

No

- Repair the (Z387) Ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

10. CHECK (F921) FUSED RUN RELAY OUTPUT CIRCUIT FOR AN OPEN




Turn the ignition on.

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

Using a 12-volt test light connected to ground, probe the (F921) Fused Run Relay Output circuit in the Front Blower Motor Relay connector.
Does the test light illuminate brightly?

Yes

- Go To 11

No

- Repair the (F921) Fused Run Relay Output circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

11. CHECK (A502) FUSED B(+) CIRCUIT FOR AN OPEN




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

Using a 12-volt test light connected to ground, probe the (A502) Fused B(+) circuit in the Front Blower Motor Relay connector.
Does the test light illuminate brightly?

Yes

- Go To 12

No

- Repair the (A502) Fused B(+) circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

12. CHECK (C7) FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT FOR AN OPEN




Turn the ignition off.
Install the original Front Blower Motor Relay.
Disconnect the Front Blower Motor Power Module C1 harness connector.
Turn the ignition on.

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

Using a 12-volt test light connected to ground, back probe the (C7) Front Blower Motor Relay Output circuit in the Front Blower Motor Power Module C1 harness connector.
Does the test light illuminate brightly?

Yes

- Go To 13

No

- Repair the (C7) Front Blower Motor Relay Output circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

13. CHECK (Z134) GROUND CIRCUIT FOR AN OPEN




Turn the ignition off.
Measure the resistance of the (Z134) Ground circuit between ground and the Front Blower Motor Power Module C1 harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go To14

No

- Repair the (134) Ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

14. CHECK FRONT BLOWER MOTOR OPERATION WITH FRONT BLOWER MOTOR POWER MODULE BYPASSED




Disconnect the Front Blower Power Module C2 harness connector.
Connect a jumper wire between the (C7) Front Blower Motor Relay Output circuit in the Front Blower Motor Power Module C1 harness connector and the (C7) Blower Motor Power circuit in the Front Blower Motor Power Module C2 harness connector.
Connect a jumper wire between the (Z134) Ground circuit in the Front Blower Motor Power Module C1 harness connector and the (C75) Blower Motor Ground circuit in the Front Blower Motor Power Module C2 harness connector.
Turn the ignition on.
Does the front blower motor run at high speed?

Yes

- Go To 15

No

- Replace the Front Blower Motor.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

15. CHECK THE (C56) FRONT BLOWER CONTROL CIRCUIT FOR A SHORT TO VOLTAGE




Turn the ignition off.
Disconnect the jumper wires from the Front Blower Motor Power Module C1 and C2 harness connectors.
Disconnect the A/C Heater Control C2 harness connector.
Turn the ignition on.
Measure the voltage of the (C56) Front Blower Control circuit.
Is the voltage above 0.2 volts?

Yes

- Repair the (C56) Front Blower Control circuit for a short to voltage.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To16

16. CHECK THE (C56) FRONT BLOWER CONTROL CIRCUIT FOR AN OPEN




Turn the ignition off.
Measure the resistance of the (C56) Front Blower Control circuit between the Front Blower Power Module C1 harness connector and the A/C Heater Control C2 harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go To17

No

- Repair the (C56) Front Blower Control circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

17. CHECK FRONT BLOWER POWER MODULE OPERATION




Reconnect the Front Blower Power Module C1 and C2 harness connectors.
Turn the ignition on.
Using a 12-volt test light connected to ground, back probe the (C56) Front Blower Control circuit in the A/C Heater Control C2 harness connector.
Does the front blower motor run at high speed?

Yes

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Replace the Front Blower Power Module.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.