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

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 a 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. Check for DTCs and check if the same trouble occurs again.

   OK

   No DTCs are output.

NG → See step   4 

OK → END 

1. Disconnect the L113 radio receiver assembly connector.
   Fig 1: Identifying L113 Radio Receiver Assembly Connector Terminals

   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
   L113-15 (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
   L113-14 (B) - Body ground	Always	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *a	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 L113 radio receiver assembly connector.
2. Disconnect the R60 stereo component amplifier assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   L113-11 (MO+) - R60-4 (MI+)	Always	Below 1 Ω
   L113-25 (MO-) - R60-10 (MI-)	Always	Below 1 Ω
   L113-24 (SLDI) - R60-5 (SLDI)	Always	Below 1 Ω
   L113-11 (MO+) - Body ground	Always	10 kΩ or higher
   L113-25 (MO-) - Body ground	Always	10 kΩ or higher
   L113-24 (SLDI) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the L113 radio receiver assembly connector.
2. Disconnect the L115 display and navigation module display connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   L113-9 (MI+) - L115-3 (MO+)	Always	Below 1 Ω
   L113-23 (MI-) - L115-7 (MO-)	Always	Below 1 Ω
   L113-10 (SLDI) - L115-6 (SLDO)	Always	Below 1 Ω
   L113-9 (MI+) - Body ground	Always	10 kΩ or higher
   L113-23 (MI-) - Body ground	Always	10 kΩ or higher
   L113-10 (SLDI) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Temporarily replace the radio receiver assembly with a new or normally functioning one. Refer to REMOVAL .
2. Clear the DTCs. Refer to DTC CHECK / CLEAR .
3. Check for DTCs and check if the same trouble occurs again.

   OK

   No DTCs are output.

NG → See step   8 

OK → END