HVAC DTC Troubleshooting: 8
DTC indicator 8: A Short in the Recirculation Control Motor Circuit
NOTE: If other short circuit DTCs are indicated at the same time, there may be an open or short to body ground in the power (5 V) circuit.

1.
Problem verification:

Problem verification
?1.
Turn the ignition switch to LOCK (0) and then back to ON (II).

?2.
Do the Self-Diagnostic Function with the HVAC control unit.

?3.
Check for DTCs.

Is DTC 8 indicated?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Intermittent failure. Check for loose wires or poor connections on the recirculation control motor circuit.?
2.
Open wire check (S 5V/S5V line):

Open wire check (S 5V/S5V line)
?1.
Turn the ignition switch to LOCK (0).

?2.
Disconnect the following connectors.

?3.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0)
HVAC control unit 32P connector: disconnected
Recirculation control motor 7P connector: disconnected
Test circuit
S 5V/S5V
Test point 1
HVAC control unit 32P connector No. 16 (BLK)
Test point 2
Recirculation control motor 7P connector No. 3 (BLK)


Is there continuity?

     
YES
     
     
     
The S 5V/S5V wire is not open. Go to step 3.
     
NO
     
     
     
Repair an open in the wire between the HVAC control unit and the recirculation control motor.?
3.
Shorted wire check (RFD-P/FRD-P line to SENSOR COM/SENS-COM line):

Shorted wire check (RFD-P/FRD-P line to SENSOR COM/SENS-COM line)
?1.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0)
HVAC control unit 32P connector: disconnected
Recirculation control motor 7P connector: disconnected
Test circuit
RFD-P, SENSOR COM
Test point 1
HVAC control unit 32P connector No. 12 (WHT)
Test point 2
HVAC control unit 32P connector No. 20 (BLU)


Is there continuity?

     
YES
     
     
     
Repair a short in the wires between the HVAC control unit and the recirculation control motor.?
     
NO
     
     
     
The RFD-P/FRD-P wire to SENSOR COM/SENS-COM wire are not shorted. Go to step 4.
4.
Shorted wire check (RFD-P/FRD-P line):

Shorted wire check (RFD-P/FRD-P line)
?1.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0)
HVAC control unit 32P connector: disconnected
Recirculation control motor 7P connector: disconnected
Test circuit
RFD-P
Test point 1
HVAC control unit 32P connector No. 12 (WHT)
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short to body ground in the wire between the HVAC control unit and the recirculation control motor.?
     
NO
     
     
     
The RFD-P/FRD-P wire is OK. Go to step 5.
5.
Recirculation control motor internal resistance check (S5V and SENS-COM):

Recirculation control motor internal resistance check (S5V and SENS-COM)
?1.
Measure the resistance between test points 1 and 2.
Test condition
IG LOCK (0)
HVAC control unit 32P connector: disconnected
Recirculation control motor 7P connector: disconnected
Test circuit
S5V, SENS-COM
Test point 1
Recirculation control motor No. 1
Test point 2
Recirculation control motor No. 3


Is the resistance 6 k?1.8 k??

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
6.
Recirculation control motor internal resistance check (RFD-P and SENSOR COM):

Recirculation control motor internal resistance check (RFD-P and SENSOR COM)
?1.
Reconnect the recirculation control motor 7P connector.

?2.
Connect the battery power and ground to terminals A and B, then reverse the connections.
Terminal A
HVAC control unit 32P connector No. 9 (PUR)
Terminal B
HVAC control unit 32P connector No. 10 (ORN)

NOTE: Incorrectly applying power and ground to the motor will damage it. Follow the instructions carefully. When the motor stops running, disconnect battery power immediately.


?3.
Measure the resistance between test points 1 and 2.
Test condition
IG LOCK (0)
HVAC control unit 32P connector: disconnected
Test circuit
RFD-P, SENSOR COM
Test point 1
HVAC control unit 32P connector No. 12 (WHT)
Test point 2
HVAC control unit 32P connector No. 20 (BLU)

NOTE: Continuity between RFD-P and SENSOR COM may disappear when the motor is turned to the stop. Usually the HVAC control unit does not turn the motor to the stop.


Does resistance change between about 0?6 k?1.8 k??

     
YES
     
     
     
     
NO