Climate Control System DTC Troubleshooting: D-A4

DTC screen D-A4: Climate Control Unit Lost Communication with Center Display Unit

NOTE: The DTC may be stored due to the grounding failure or the power source failure at the center display
(the grounding inspection and the power source inspection on each control unit are required prior to this checking process).

Problem verification:

Problem verification

?1.	Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

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

?3.	Check for DTCs.

Is Error on the DTC screen D-A4 indicated?


	YES

Go to step 2.


	NO

Intermittent failure, the system is OK at this time. Check for loose wires or poor connections.?

Open wire check (B-CAN_H line):

Open wire check (B-CAN_H line)

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.

Disconnect the following connectors.

Audio unit connector A (24P) (without navigation)

Audio-navigation unit connector A (24P) (with navigation)

Climate control unit connector A (32P)

?3.

Check for continuity between test points 1 and 2.

Without navigation

Test condition	Vehicle OFF (LOCK) mode
	Audio unit connector A (24P): disconnected
	Climate control unit connector A (32P): disconnected
Test point 1	Audio unit connector A (24P) No. 14
Test point 2	Climate control unit connector A (32P) No. 25

With navigation

Test condition	Vehicle OFF (LOCK) mode
	Audio-navigation unit connector A (24P): disconnected
	Climate control unit connector A (32P): disconnected
Test point 1	Audio-navigation unit connector A (24P) No. 14
Test point 2	Climate control unit connector A (32P) No. 25

Is there continuity?


	YES

The B-CAN_H wire is OK. Go to step 3.


	NO

Repair an open in the B-CAN_H wire.?

Open wire check (B-CAN_L line):

Open wire check (B-CAN_L line)

?1.

Check for continuity between test points 1 and 2.

Without navigation

Test condition	Vehicle OFF (LOCK) mode
	Audio unit connector A (24P): disconnected
	Climate control unit connector A (32P): disconnected
Test point 1	Audio unit connector A (24P) No. 24
Test point 2	Climate control unit connector A (32P) No. 8

With navigation

Test condition	Vehicle OFF (LOCK) mode
	Audio-navigation unit connector A (24P): disconnected
	Climate control unit connector A (32P): disconnected
Test point 1	Audio-navigation unit connector A (24P) No. 24
Test point 2	Climate control unit connector A (32P) No. 8

Is there continuity?


	YES

Replace the audio unit (without navigation) or the audio-navigation unit (with navigation).?


	NO

Repair an open in the B-CAN_L wire.?