U–66
TROUBLESHOOTING
4* INSPECT TO SEE WHETHER MALFUNCTION
IS IN BLOWER RELAY SYSTEM OR POWER
MOS FET SYSTEM
• Turn ignition switch to ON position.
• Test voltage at the following terminal of
blower motor.
— Terminal B (blower motor operation
signal)
• Is voltage approximately 12 V?
Yes Go to Step 8.
No Go to next step.
5* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN FUSE BLOCK AND
BLOWER RELAY) OR ELSEWHERE
• Test voltage at the following terminal of
blower relay.
— Terminal A (IG2 signal)
— Terminal C (B+ signal)
• Is voltage approximately 12 V?
Yes Go to next step.
No Repair wiring harness between blower relay and BLOWER
40 A fuse, then go to Step 15.
6* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN BLOWER RELAY
AND GROUND) OR ELSEWHERE
• Test voltage at the following terminal of
blower relay.
— Terminal E (GND signal)
• Is voltage approximately 0 V?
Yes Go to next step.
No Repair wiring harness between blower relay and ground,
then go to Step 15.
7* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN BLOWER RELAY
AND BLOWER MOTOR) OR BLOWER RELAY
• Test voltage at the following terminal of
blower relay.
— Terminal D (blower motor operation
signal)
• Is voltage approximately 12 V?
Yes Repair wiring harness between blower relay and blower
motor, then go to Step 15.
No Replace blower relay, then go to Step 15.
8* INSPECT TO SEE WHETHER MALFUNCTION
IS IN BLOWER MOTOR OR ELSEWHERE
• Test voltage at the following terminal of
blower motor.
— Terminal B (blower motor operation
signal)
• Is voltage approximately 12 V?
Yes Go to next step.
No Inspect blower motor, then go to Step 15.
9* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN BLOWER MOTOR
AND POWER MOS FET) OR ELSEWHERE
• Test voltage at the following terminal of
power MOS FET.
— Terminal C (blower motor operation
signal)
• Is voltage approximately 12 V?
Yes Go to next step.
No Repair wiring harness between blower motor and power
MOS FET, then go to Step 15.
10* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN POWER MOS FET
AND GROUND) OR ELSEWHERE
• Test voltage at the following terminal of
power MOS FET.
— Terminal A (blower motor operation
signal)
• Is voltage approximately 0 V?
Yes Go to next step.
No Repair wiring harness between power MOS FET and
ground, then go to Step 15.
11 INSPECT BLOWER UNIT
• Inspect fan in blower unit.
— Is fan free of interference with blower unit
case?
— Is fan free of foreign material and
obstruction?
• Is fan okay?
Yes Go to next step.
No Remove obstruction, repair or replace fan and blower unit
case, then go to Step 15.
STEP INSPECTION ACTION
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