Code No.B1857:
Microphone Connection
caution |
When replacing the ECU, always
check that the communication circuit is normal.
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DIAGNOSTIC FUNCTION
When the system detects that the microphone is disconnected for 5 seconds or more, the
e-Call control unit sets diagnosis code No. B1857.
note |
When diagnosis code No. B1857 is set, the e-Call switch flashes in green.
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PROBABLE CAUSES
- Damaged wiring harness or connector(s)
- Malfunction of microphone
- Malfunction of multivision display <Vehicles with smartphone link display
audio or hands free-ECU>
- Malfunction of e-Call control unit
DIAGNOSIS PROCEDURE
STEP 1. Voltage measurement at the microphone connector
(MACC terminal).
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(1)Disconnect the microphone connector, and measure at the wiring harness side.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Check the voltage between the microphone connector terminal MACC and body earth. OK: Approximately 5 V
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Q.
Is the check result normal?
Go to Step 3
Go to Step 2
STEP 2. Resistance measurement at between the e-Call control unit
and the microphone connector (SNSI or MACC terminals).
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(1)Disconnect the e-Call control unit and microphone connector, and measure at the
wiring harness side.
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(2)Check the resistance between the e-Call control unit connector terminal SNSI and
microphone connector terminal MACC. OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
Replace the e-Call control unit (Refer to
).
Repair the connector(s) or wiring harness.
STEP 3. Resistance measurement at the microphone connector (S99 terminal).
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(1)Disconnect the microphone connector, and measure at the wiring harness side.
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(2)Check the resistance between the microphone terminal S99 and body earth. OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
Replace the microphone (Refer to
).
Go to Step 4
STEP 4. Resistance measurement at the e-Call control unit connector
(MI- terminal).
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(1)Disconnect the e-Call control unit and microphone connector, and measure at the
wiring harness side.
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(2)Check the resistance between the e-Call control unit connector terminal MI- microphone connector
terminal S99. OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
YES <Vehicles without smartphone link display audio and hands free-ECU>
: Go to Step 7
YES <Vehicles with smartphone link display audio or hands free-ECU>
: Go to Step 5
Repair the connector(s) or wiring harness.
STEP 5. Resistance measurement at the e-Call control unit connector
(MO- terminal).
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(1)Disconnect the e-Call control unit, and measure at the wiring harness side.
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(2)Check the resistance between the e-Call control unit connector terminal MO- and
body earth. OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
Go to Step 7
Go to Step 6
STEP 6. Resistance measurement at between the e-Call control unit
connector (MO- terminal) and the smartphone link display audio connector (MIC- terminal)
or hands free-ECU connector (MIC- terminal).
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(1)Disconnect the e-Call control unit and smartphone link display audio or hands free-ECU,
and measure at the wiring harness side.
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(2)Check the resistance between the e-Call control unit connector terminal MO- and
smartphone link display audio connector terminal MIC- or hands free-ECU connector terminal
MIC-. OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
Replace the multivision display (Refer to
)
or Replace the hands free-ECU (Refer to
).
Repair the connector(s) or wiring harness.
STEP 7. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the e-Call control unit.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Execute "Test" on the M.U.T.-III special function.
- Item No.5: Microphone check (Door speaker)
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(4)Check if diagnosis code is set.
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Q.
Is the diagnosis code set?
Replace the e-Call control unit (Refer to
).
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction).