DTC indicator light L: An Open or Short in the Mode Control Motor Circuit

WARNING: This page is about a different car, the 2003 Acura 3.2CL and 2002 Acura 3.2CL. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect the mode control motor 10P connector.
Disconnect climate control unit connectors A (12P) and B (20P).
Check for continuity between body ground and climate control unit connector A (12P) terminals No. 1 and 6 individually, and between body ground and climate control unit connector B (20P) terminals No. 15, 17, 18, 19 and 20 individually.

Fig 1: Checking Continuity (Climate Control Unit Connector A)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: Checking Continuity (Climate Control Unit Connector B)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity ?
1. YES : Repair any short to body ground in the wire(s) between the climate control unit and the mode control motor.
2. NO : Go to step 4.
Turn the ignition switch ON (II), and check the same terminals for voltage.

Fig 3: Checking Voltage (Climate Control Unit Connector A)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 4: Checking Voltage (Climate Control Unit Connector B)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there any voltage ?
1. YES : Repair short to power in the wire between the climate control unit and the mode control motor. This short also damages the climate control unit. Repair the short to power before replacing the climate control unit.
2. NO : Go to step 5.

Turn the ignition switch OFF, and check for continuity between following terminals of climate control unit connectors A (12P) and B (20P) and the mode control motor 10P connector.

MODE CONTROL MOTOR CIRCUIT CONTINUITY

Climate Control Unit		Mode Control Motor 10P Connector
Connector A (12P)
1		2
6		1
Connector B (20P)
15		10
17		6
17		9
18		8
19		4
19		7
20		5

Fig 5: Checking Continuity

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity ?

YES : Check for loose wires or poor connections at climate control unit connectors A (12P) and B (20P) and at the mode control motor 10P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/ indication goes away, replace the original climate control unit.
NO : Repair any open in the wire(s) between the climate control unit and the mode control motor.