DTC B1591: No Response from Audio HU; DTC B15D1: Audio HU Disconnected: Procedure

1. Check for optional components.
   1. Check that optional components (including associated wiring) which generate radio waves are not installed.

      Result

      Result	Proceed to
      Optional components (including associated wiring) are installed.	A
      Optional components (including associated wiring) are not installed.	B

      HINT: 

      • Electrical noise from radio waves generated by optional components or the wiring for those components may affect MOST communication.
      • This DTC may be stored when an MOST communication error occurs due to electrical noise.

B → See step   3 

A: Go to next step 

1. Remove optional components (including associated wiring).
   NOTE:

   Do not remove optional components or associated wiring without the permission of the customer.

NEXT: Go to next step 

1. Clear the DTCs. Refer to DTC CHECK / CLEAR .
2. Recheck for DTCs and check if the same DTC is output again.

   OK

   No DTCs are output.

NG → See step   4 

OK → END 

1. Disconnect the G12 radio receiver assembly connector.
   Fig 1: G12 Radio Receiver Assembly Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G12-15 (GND) - Body ground	Always	Below 1 Ω

3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   G12-14 (B) - G12-15 (GND)	Engine switch off	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Radio Receiver Assembly)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the G12 radio receiver assembly connector.
   Fig 2: G12 Radio Receiver Assembly Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the G14 remote touch connector.
   Fig 3: G14 Remote Touch Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G12-9 (MI+) - G14-1 (MO+)	Always	Below 1 Ω
   G12-23 (MI-) - G14-2 (MO-)	Always	Below 1 Ω
   G12-10 (SLDI) - G14-3 (SLDO)	Always	Below 1 Ω
   G12-9 (MI+) - Body ground	Always	10 kΩ or higher
   G12-23 (MI-) - Body ground	Always	10 kΩ or higher
   G12-10 (SLDI) - Body ground	Always	10 kΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Radio Receiver Assembly)
   *2	Front view of wire harness connector (to Remote Touch)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the G12 radio receiver assembly connector.
   Fig 4: G12 Radio Receiver Assembly Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the O15 stereo component amplifier assembly connector.
   Fig 5: O15 Stereo Component Amplifier Assembly Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G12-11 (MO+) - O15-4 (MI+)	Always	Below 1 Ω
   G12-25 (MO-) - O15-10 (MI-)	Always	Below 1 Ω
   G12-24 (SLDI) - O15-5 (SLDI)	Always	Below 1 Ω
   G12-11 (MO+) - Body ground	Always	10 kΩ or higher
   G12-25 (MO-) - Body ground	Always	10 kΩ or higher
   G12-24 (SLDI) - Body ground	Always	10 kΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Radio Receiver Assembly)
   *2	Front view of wire harness connector (to Stereo Component Amplifier Assembly)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Replace the radio receiver assembly. Refer to REMOVAL .
2. Clear the DTCs. Refer to DTC CHECK / CLEAR .
3. Recheck for DTCs and check if the same DTC is output again.

   OK

   No DTCs are output.

NG → See step   8 

OK → END