*FRONT BLOWER MOTOR INOPERATIVE (MTC)
For a complete wiring diagram Refer to Section 8W.
| Possible Causes |
| PDC FUSE #1 OPEN |
| JB FUSE #10 OPEN |
| (C7) FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT SHORTED TO (Z387) GROUND CIRCUIT |
| (A502) FUSED B(+) CIRCUIT SHORTED TO (Z387) GROUND CIRCUIT |
| (C7) FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT SHORTED TO GROUND |
| (A502) FUSED B(+) CIRCUIT SHORTED TO GROUND |
| (F921) FUSED RUN RELAY OUTPUT CIRCUIT SHORTED TO GROUND |
| (C105) REAR HVAC CONTROL CIRCUIT (IF EQUIPPED) SHORTED TO GROUND |
| (C75) BLOWER HIGH SPEED CIRCUIT OPEN |
| (Z387) GROUND CIRCUIT OPEN |
| (F921) FUSED RUN RELAY OUTPUT CIRCUIT OPEN |
| (A502) FUSED B(+) CIRCUIT OPEN |
| (C7) FRONT BLOWER MOTOR RELAY OUTPUT CIRCUIT OPEN |
| (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT SHORTED TO (C121) SENSOR GROUND CIRCUIT |
| (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT SHORTED TO GROUND |
| (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT OPEN |
| (Z134) GROUND CIRCUIT OPEN |
| JUNCTION BLOCK (JB) |
| POWER DISTRIBUTION CENTER (PDC) |
| FRONT BLOWER MOTOR RELAY |
| FRONT BLOWER MOTOR |
| A/C HEATER CONTROL |
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 6.
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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.
Disconnect the Front Blower Motor harness connector.
Remove the Front Blower Motor Relay from the PDC.
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 in accordance with the Service Information and replace the fuse.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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 in accordance with the Service Information and replace the fuse.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Go To 5
5. CHECK FRONT BLOWER MOTOR OPERATION WITH A SUBSTITUTE RELAY INSTALLED
Reconnect the Front Blower Motor 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 in accordance with the Service Information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Replace the Front Blower Motor in accordance with the Service Information. Replace the fuse and reinstall the original Front Blower Motor Relay.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
6. 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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Reinstall the fuse and Go To 7.
7. 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 in accordance with the Service Information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Go To 8
8. 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 9
No
- Repair the (Z387) Ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
9. 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 10
No
- Repair the (F921) Fused Run Relay Output circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
10. 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 11
No
- Repair the (A502) Fused B(+) circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
11. 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 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 harness connector.
Does the test light illuminate brightly?
Yes
- Go To 12
No
- Repair the (C7) Front Blower Motor Relay Output circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
12. CHECK THE (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO THE (C121) SENSOR GROUND CIRCUIT
Turn the ignition off.
Disconnect the A/C Heater Control C2 harness connector.
Measure the resistance between the (C41) Blower Switch Position Signal circuit and the (C121) Sensor Ground circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10K ohms?
Yes
- Repair the (C41) Blower Switch Position Signal circuit for a short to the (C121) Sensor Ground circuit.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Go To 13
13. CHECK THE (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO GROUND
Disconnect the A/C Heater Control C3 harness connector.
Measure the resistance of the (C41) Blower Switch Position Signal circuit between ground and the A/C Heater Control C3 harness connector.
Is the resistance below 10K ohms?
Yes
- Repair the (C41) Blower Switch Position Signal circuit for a short to ground.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Go To 14
14. CHECK (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR AN OPEN
Measure the resistance of the (C41) Blower Switch Position Signal circuit between the A/C Heater Control C2 harness connector and the A/C Heater Control C3 harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 15
No
- Repair the (C41) Blower Switch Position Signal circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
15. CHECK FRONT BLOWER MOTOR OPERATION BY BYPASSING THE A/C HEATER CONTROL
Reconnect the A/C Heater Control C2 harness connector.
Reconnect the A/C Heater Control C3 harness connector.
Reconnect the Front Blower Motor harness connector.
Connect a jumper wire between ground and the (C75) Blower High Speed circuit in the Front Blower Motor harness connector.
Turn the ignition on.
Does the blower motor run at high speed?
Yes
- Go To 16
No
- Replace the Front Blower Motor in accordance with the Service Information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
16. CHECK THE (C75) BLOWER HIGH SPEED CIRCUIT FOR AN OPEN
Turn the ignition off.
Disconnect the A/C Heater Control C3 harness connector.
Disconnect the Front Blower Motor harness connector.
Measure the resistance of the (C75) Blower High Speed circuit between the A/C Heater Control C3 harness connector and the Front Blower Motor harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 17
No
- Repair the (C75) Blower High Speed circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
17. CHECK THE (Z134) GROUND CIRCUIT FOR AN OPEN
Measure the resistance of the (Z134) Ground circuit between ground and the A/C Heater Control C3 harness connector.
Is the resistance below 5.0 ohms?
Yes
- Replace the A/C Heater Control in accordance with the Service Information.
No
- Repair the (Z134) Ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).