Blower Motor Circuit Troubleshooting
Blower Motor Circuit Troubleshooting1. Turn the ignition switch ON (II) and the heater fan switch ON.
Does the blower run?
YES - Go to step 2.
NO - Go to step 16.
2. Turn the heater fan switch OFF.
3. Make sure the ignition switch is ON (II).
Does the blower motor run?
YES - Go to step 4.
NO - Go to step 9.
4. Turn the ignition switch OFF.
5. Disconnect the blower motor 2P connector.
6. Disconnect the blower resistor 5P connector.
7. Disconnect the heater fan switch 7P connector.
8. Check for continuity between the No.3, 4, 5 and 6 terminals of the heater fan switch 7P connector and body ground individually.
Is there continuity?
YES - Repair any short to body ground in the wire(s) between the blower motor, the blower resistor and the heater fan switch.
NO - Replace the heater fan switch.
9. Turn the ignition switch OFF.
10. Disconnect the blower resistor 5P connector.
11. Measure the resistance between the No.1 and No.5 terminals of the blower resistor.
Is there about 3 - 3.5 Ohm?
YES - Go to step 12.
NO - Replace the blower resistor.
12. Reconnect the blower resistor 5P connector.
13. Disconnect the heater fan switch 7P connector.
14. Turn the ignition switch ON (II).
15. Ground each of the heater fan switch 7P connector terminals individually in the following order: No.4, 5,6 and 3.
Does the blower motor run at progressively higher speeds?
YES - Replace the heater fan switch.
NO - Repair any open or cause of excessive resistance in the appropriate wire(s) between the blower resistor and the heater fan switch.
16. Turn the heater fan switch OFF and the ignition switch OFF.
17. Check the No.56 (40 A) fuse in the under-hood fuse/relay box, and the No.3 (7.5 A) fuse in the driver's under-dash fuse/relay box.
Are the fuses OK?
YES - Go to step 18.
NO - Replace the fuse(s), and recheck.
18. Connect the No.2 terminal of the blower motor 2P connector to body ground with a jumper wire.
19. Turn the ignition switch ON (II).
Does the blower motor run?
YES - Go to step 20.
NO - Go to step 27.
20. Turn the ignition switch OFF.
21. Disconnect the jumper wire.
22. Disconnect the heater fan switch 7P connector.
23. Turn the ignition switch ON (II).
24. Measure the voltage between the No.3 terminal of the heater fan switch 7P connector and body ground.
Is there battery voltage?
YES - Go to step 25.
NO - Repair open in the wire between the blower motor and the heater fan switch.
25. Turn the ignition switch OFF.
26. Check for continuity between the No.1 terminal of the heater fan switch 7P connector and body ground.
Is there continuity?
YES - Replace the heater fan switch.
NO - Check for an open in the wire between the heater fan switch and body ground. If the wire is OK, check for poor ground at G401.
27. Disconnect the jumper wire.
28. Disconnect the blower motor 2P connector.
29. Measure the voltage between the No.1 terminal of the blower motor 2P connector and body ground.
Is there battery voltage?
YES - Replace the blower motor.
NO - Go to step 30.
30. Turn the ignition switch OFF.
31. Remove the blower motor relay from the under-hood fuse/relay box, and test it.
Is the relay OK?
YES - Go to step 32.
NO - Replace the blower motor relay.
32. Measure the voltage between the No.4 terminal of the blower motor relay 4P socket and body ground.
Is there battery voltage?
YES - Go to step 33.
NO - Replace the under-hood fuse/relay box.
33. Turn the ignition switch ON (II).
34. Measure the voltage between the No.1 terminal of the blower motor relay 4P socket and body ground.
Is there battery voltage?
YES - Go to step 35.
NO - Repair open in the wire between the No.3 fuse in the driver's under-dash fuse/relay box and the blower motor relay.
35. Turn the ignition switch OFF.
36. Check for continuity between the No.2 terminal of the blower motor relay 4P socket and body ground.
Is there continuity?
YES - Repair open in the wire between the blower motor relay and the blower motor.
NO - Check for an open in the wire between the blower motor relay and body ground. If the wire is OK, check for poor ground at G201.