Communication circuit self-diagnostic function (without 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 fan Up triangle button and then 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). Record any segments that light and go to step 5.
Turn the ignition switch OFF, and then ON (II).
At the rear climate control panel, set the rear fan control dial OFF. The rear temperature control dial to Max Cool, and the rear control dial to select Vent.
Turn the ignition switch ON (II) and then press the rear control button five times within 10 seconds. The rear control indicator will turn off, and then the communication circuit self-diagnostic function will start. The rear control indicator will blink to indicate any problems.
- If no segment other than segment A lights in the climate control panel and the rear climate control indicator does not blink, the communication circuit is OK.
- If any segment other than segment A lights, and/or the rear control indicator blinks, record the segments and/or blinks, and then go to step 8.
Fig 1: Identifying Climate Control Panel And Rear Control Panel Button
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: Example Of Fan Indicator Blinking Pattern
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Refer to the FRONT FAN SEGMENTS AND REAR CONTROL INDICATOR and perform the appropriate diagnosis for the error indicated by the front fan segments and rear control indicator.

FRONT FAN SEGMENTS AND REAR CONTROL INDICATOR

Front Fan Segment	Rear control indicator (number of blinks)	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 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 control panel
	1, 2, 3, and/or 4	Open in IG2 to rear control panel Open in ground to rear control panel Faulty rear control panel Faulty climate control panel	Rear control panel power and ground circuit troubleshooting (see REAR CONTROL PANEL POWER AND GROUND CIRCUIT TROUBLESHOOTING ) Replace the rear control panel Replace the climate control panel
E	4	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	1	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	2	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	4	Open in communication circuit to rear control panel and climate control unit Faulty rear control panel	Climate control communication circuit troubleshooting (see CLIMATE CONTROL COMMUNICATION CIRCUIT TROUBLESHOOTING ) Replace the rear control panel