Audio Communication Line Circuit Troubleshooting
  1. Disconnect climate control unit connector A (28P) and the center display unit 12P connector.
  1. Check for continuity between the following terminals of heater control unit connector A (28P) and the center display unit 12P connector.
    28P:
    12P:
    No. 19
    No. 7
    No. 20
    No. 8

Is there continuity?
YES -
Go to Step 3 .
NO -
Repair open in the wire between heater control unit connector A (28P) and the center display unit 12P connector.■
  1. Check for continuity between body ground and heater control unit connector A (28P) No. 19 and No. 20 terminals individually.
Is there continuity?
YES -
Repair short to body ground in the wire between heater control unit connector A (28P) and the center display unit 12P connector.■
NO -
Go to Step 4 .
  1. Reconnect heater control unit connector A (28P).
  1. Connect the center display unit 12P connector No. 7 and No. 8 terminals with a jumper wire.
  1. Turn the ignition switch to ON (II).
  1. Press and hold the DEF button and OFF button.
Is the DEF button LED blinking?
YES -
NO -