DTC B1775: Microphone Input/Output Shorted to Power or Open (HandsFreeLink Control Unit)

NOTE: 

• Check the vehicle 12 volt battery condition first - Refer to: 12 Volt Battery Test (Without SH-AWD) or 12 Volt Battery Test (With SH-AWD) .
• Before you troubleshoot, make sure to follow the General Troubleshooting Information .
• Check the connectors for poor connections or loose terminals.

1. Problem verification

   -1. Check for HFL DTCs.

   Is DTC B1775 indicated?

   YES 

   The failure is duplicated, go to step 2.

   NO 

   Intermittent failure, the system is OK at this time.

2. Shorted wire check (MIC SIG L line to power)

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

   - 2. Disconnect the following connectors.

   HandsFreeLink control unit connector A (32P)

   Front HFL-ANC/active sound control microphone 8P connector

   - 3. Turn the vehicle to the ON mode.

   - 4. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	HandsFreeLink control unit connector A (32P): disconnected
   	Front HFL-ANC/active sound control microphone 8P connector: disconnected
   Test point 1	Front HFL-ANC/active sound control microphone 8P connector No. 2
   Test point 2	Body ground

   Is there more than 8.0 V?

   YES 

   There is a short to power in the wire between the HandsFreeLink control unit and the front HFL-ANC/active sound control microphone. Replace the affected shielded harness.

   NO 

   The MIC SIG L wire is not shorted to power. Go to step 3.

3. Determine possible failure area (MIC SIG L line, others)

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

   - 2. Reconnect HandsFreeLink control unit connector A (32P).

   - 3. Turn the vehicle to the ON mode.

   - 4. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Front HFL-ANC/active sound control microphone 8P connector: disconnected
   Test point 1	Front HFL-ANC/active sound control microphone 8P connector No. 2
   Test point 2	Body ground

   Is there about 8.0 V?

   YES 

   Go to step 5.

   NO 

   Go to step 4.

4. Open wire check (MIC SIG L line)

   -1. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Front HFL-ANC/active sound control microphone 8P connector: disconnected
   Test point 1	HandsFreeLink control unit connector A (32P) No. 2 - Refer to: HandsFreeLink Control Unit Connector For Inputs And Outputs (2015-17) or HandsFreeLink Control Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	Body ground

   Is there about 8.0 V?

   YES 

   There is an open in the wire between the HandsFreeLink control unit and the front HFL-ANC/active sound control microphone. Replace the affected shielded harness.

   NO 

   Replace the HandsFreeLink control unit .

5. Open wire check (MIC GND line)

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

   - 2. Disconnect the following connector.

   HandsFreeLink control unit connector A (32P)

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Front HFL-ANC/active sound control microphone 8P connector: disconnected
   	HandsFreeLink control unit connector A (32P): disconnected
   Test point 1	HandsFreeLink control unit connector A (32P) No. 1 - Refer to: HandsFreeLink Control Unit Connector For Inputs And Outputs (2015-17) or HandsFreeLink Control Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	Front HFL-ANC/active sound control microphone 8P connector No. 1

   Is there continuity?

   YES: Without navigation

   The MIC GND wire is OK. Go to step 6.

   YES: With navigation

   The MIC GND wire is OK. Go to step 7.

   NO 

   There is an open in the wire between the HandsFreeLink control unit and the front HFL-ANC/active sound control microphone. Replace the affected shielded harness.

6. Front HFL-ANC/active sound control microphone check (substitution)

   -1. Substitute a known-good front HFL-ANC/active sound control microphone.

   - 2. Reconnect HandsFreeLink control unit connector A (32P).

   - 3. Check for HFL DTCs.

   Is DTC B1775 indicated?

   YES 

   Replace the HandsFreeLink control unit .

   NO 

   Replace the original front HFL-ANC/active sound control microphone .

7. Shorted wire check (NAVI HFT MIC+ line to power)

   -1. Disconnect the following connector.

   Audio-navigation unit connector F (18P)

   - 2. Turn the vehicle to the ON mode.

   - 3. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Front HFL-ANC/active sound control microphone 8P connector: disconnected
   	HandsFreeLink control unit connector A (32P): disconnected
   	Audio-navigation unit connector F (18P): disconnected
   Test point 1	Audio-navigation unit connector F (18P) No. 13 - Refer to: Audio-Navigation Unit Connector For Inputs And Outputs (With Auto Idle Stop System) (2015-17) or Audio-Navigation Unit Connector for Inputs and Outputs (Without Auto Idle Stop System) (2015-17) or Audio-Navigation Unit Connector for Inputs and Outputs (Undefined) (2018), or Audio-Navigation Unit Connector for Inputs and Outputs (2019)
   Test point 2	Body ground

   Is there about 8.0 V or more?

   YES 

   There is a short to power in the wire between the HandsFreeLink control unit and the audio-navigation unit. Replace the affected shielded harness.

   NO 

   The NAVI HFT MIC+ wire is not shorted to power. Go to step 8.

8. Determine possible failure area (audio-navigation unit, others)

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

   - 2. Reconnect HandsFreeLink control unit connector A (32P).

   - 3. Reconnect the front HFL-ANC/active sound control microphone 8P connector.

   - 4. Check for HFL DTCs.

   Is DTC B1775 indicated?

   YES 

   Go to step 9.

   NO 

   Replace the audio-navigation unit .

9. Front HFL-ANC/active sound control microphone check (substitution)

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

   - 2. Substitute a known-good front HFL-ANC/active sound control microphone.

   - 3. Check for HFL DTCs.

   Is DTC B1775 indicated?

   YES 

   Replace the HandsFreeLink control unit .

   NO 

   Replace the original front HFL-ANC/active sound control microphone .