DTC Troubleshooting: B2991
DTC B2991:
 Heater Control Unit Lost Communication with Audio HVAC Subdisplay Unit (with audio system) or HVAC Subdisplay Unit (without audio system)
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch OFF and then ON(II).
  1. Do the self-diagnostic with the HDS.
  1. Check for DTCs.
Is DTC B2991 indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure, check for loose wires or poor connections on the audio HVAC subdisplay unit or HVAC subdisplay unit and heater control unit circuit.■
  1. Turn the ignition switch OFF.
  1. Disconnect the heater control unit 32P connector.
  1. Disconnect audio HVAC subdisplay unit connector E (5P) (with audio system) or the HVAC subdisplay unit 10P connector (without audio system).
  1. Check the continuity between the following terminals of the heater control unit 32P connector and audio HVAC subdisplay unit connector E (5P) (with audio system) or the HVAC subdisplay unit 10P connector (without audio system).
Is there continuity?
YES -
Go to Step 9 .
NO -
Repair open in the wire(s) between the heater control unit and the audio HVAC subdisplay unit (with audio system) or the HVAC subdisplay unit (without audio system).■