*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

Is the fuse open?

Yes

Replace the fuse and Go To 2.

Reinstall the fuse and Go To 6.

2.CHECK FRONT BLOWER MOTOR OPERATION

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).

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

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).

Go To 4

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

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).

Go To 5

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

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).

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

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).

Reinstall the fuse and Go To 7.

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

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).

Go To 8

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

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 9

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

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 10

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.

Does the test light illuminate brightly?

Yes

Go To 11

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

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 12

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

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).

Go To 13

13.CHECK THE (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO GROUND

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).

Go To 14

14.CHECK (C41) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR AN OPEN

Is the resistance below 5.0 ohms?

Yes

Go To 15

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

Does the blower motor run at high speed?

Yes

Go To 16

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

Is the resistance below 5.0 ohms?

Yes

Go To 17

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

Is the resistance below 5.0 ohms?

Yes

Replace the A/C Heater Control in accordance with the Service Information.

Repair the (Z134) Ground circuit for an open.
Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).