Communication Circuit self-diagnostic Function Test (with rear climate control)

WARNING: This page is about a different car, the 2006 Honda Odyssey and 2005 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.

The climate control unit has a communication circuit self-diagnostic function. Perform the following steps to test the communication circuit.

Turn the ignition switch OFF, and then ON (II).
At the climate control panel, press and hold the OFF button. While holding the OFF button, press the rear window defogger button five times within 10 seconds. Release the OFF button. All the LEDs and LCD segments should blink three times.
- If none of the LEDs or LCD segments blink, go to climate control panel power and ground circuit troubleshooting (see CLIMATE CONTROL PANEL POWER AND GROUND CIRCUIT TROUBLESHOOTING ).
- If one or more LEDs or LCD segments do not blink, but at least one LED or LCD segment does blink, replace the climate control panel.
- If all LEDs and LCD segments blink, go to step 3.
Turn the ignition switch OFF, and then ON (II).
At the rear climate control panel press and hold the OFF button. While holding the OFF button, press the rear Down triangle button five times within 10 seconds. Release the OFF button. All the LCD segments should blink three times.
- If none of the LCD segments blink, go to rear climate control panel power and ground circuit troubleshooting (see REAR CONTROL PANEL POWER AND GROUND CIRCUIT TROUBLESHOOTING ).
- If one or more LCD segments do not blink, but at least one LCD segment does blink, replace the rear climate control panel.
- If all LCD segments blink, go to step 5.
Turn the ignition switch OFF, and then ON (II).
At the climate control panel, press and hold the fan Up triangle button and then the OFF button. While holding both buttons, the fan indicator will light the segment A. If there is any problem in the system, the fan indicator will light corresponding segment (B through E). Record any segments that light and go to step 7.
Turn the ignition switch OFF, and then ON (II).
At the rear climate control panel, press and hold the rear fan Up triangle button and then the OFF button. While holding both buttons, the fan indicator will light the segment A. If there is any problem in the system, the fan indicator will light the corresponding segment (B through E).
- If no segment other than segment A light in either the climate control panel or the rear climate control panel, communication circuit is OK.
- If any segment other than segment A light, record the segments and then go to step 9.
Fig 1: Identifying Climate Control Panel And Rear Climate Control Panel Button
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Refer to the POSSIBLE CAUSES CHART and perform the appropriate diagnosis for the error indicated by the front and rear fan segments.

POSSIBLE CAUSES CHART

Front Fan Segment	Rear Fan Segment	Possible Cause	Perform the following tests
B, C, D, and/or E		Open in IG2 to climate control panel Open in ground to climate control panel Faulty climate control panel Faulty rear climate control panel	Climate control panel power and ground circuit troubleshooting (see CLIMATE CONTROL PANEL POWER AND GROUND CIRCUIT TROUBLESHOOTING ) Replace the climate control panel Replace the rear climate control panel.
	B, C, D, and/or E	Open in IG2 to rear climate control panel Open in ground to rear climate control panel Faulty rear climate control panel Faulty climate control panel	Rear climate control panel power and ground circuit troubleshooting (see REAR CONTROL PANEL POWER AND GROUND CIRCUIT TROUBLESHOOTING ) Replace the rear climate control panel Replace the climate control panel
E	E	Open in IG2 circuit to climate control unit Open in ground circuit to climate control unit Open in communication circuit between climate control unit and all other units Short to ground in communication circuit Faulty climate control unit	Climate control panel power and ground circuit troubleshooting (see CLIMATE CONTROL PANEL POWER AND GROUND CIRCUIT TROUBLESHOOTING ) Climate control communication circuit troubleshooting (see CLIMATE CONTROL COMMUNICATION CIRCUIT TROUBLESHOOTING ) Replace the climate control unit
E	B	Open in communication circuit to climate control panel and climate control unit Faulty climate control panel	Climate control communication circuit troubleshooting (see CLIMATE CONTROL COMMUNICATION CIRCUIT TROUBLESHOOTING ) Replace the climate control panel
C	C	Open in communication circuit to rear climate control unit and climate control unit Faulty rear climate control unit	Climate control communication circuit troubleshooting (see CLIMATE CONTROL COMMUNICATION CIRCUIT TROUBLESHOOTING ) Replace the rear climate control unit
D	E	Open in communication circuit to rear climate control panel and climate control unit Faulty rear climate control panel	Climate control communication circuit troubleshooting (see CLIMATE CONTROL COMMUNICATION CIRCUIT TROUBLESHOOTING ) Replace the rear climate control panel