DTC B1856: Speaker Connection: Diagnosis

Required Special Tools

MB991223: Wiring harness set
MB992006: Extra fine probe

STEP 1. Using scan tool (M.U.T.-IIISE), check the special function.
CAUTION: To prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
1. Connect scan tool (M.U.T.-IIISE). Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) ."
2. Check the ECALL speaker (Refer to SPECIAL FUNCTION TABLE ).
  Test
  - Item No. 2: Emergency speaker check (Beep)
  OK: A beep sound is heard (during the test).
  
  Q: Is the check result normal?
  
  YES: Go to Step 6.
  
  NO: Go to Step 2.
STEP 2. Resistance measurement at the TCU connector (SPO+ terminal).
1. Disconnect the TCU connector, and measure at the wiring harness side.
2. Check the resistance between the TCU connector terminal SPO+ and SPO-.
  OK: 1.5 - 70 ohms
3. Check the resistance between the TCU connector (SPO+ terminal) and body ground.
  OK: No continuity
  
  Q: Is the check result normal?
  
  YES: Go to Step 6.
  
  NO: Go to Step 3.
STEP 3. Resistance measurement at the TCU connector (SPO+, SPO- terminals).
1. Disconnect the TCU connector and the ECALL relay box assembly connector, and measure at the wiring harness side.
2. Check the resistance between the TCU connector (SPO+ terminal) and the ECALL relay box assembly connector (ESI+ terminal).
  OK: The resistance should be 2 ohms or less
3. Check the resistance between the TCU connector (SPO- terminal) and the ECALL relay box assembly connector (ESI- terminal).
  OK: The resistance should be 2 ohms or less
4. Check the resistance between the TCU connector (SPO+ terminal) and body ground.
  OK: No continuity
5. Check the resistance between the TCU connector (SPO- terminal) and body ground.
  OK: No continuity
  
  Q: Is the check result normal?
  
  YES: Go to Step 4.
  
  NO: Repair the connector(s) or wiring harness.
STEP 4. Resistance measurement at the ECALL relay box assembly connector (ESO-, ESO+ terminals).
1. Disconnect the ECALL relay box assembly connector, and measure at the wiring harness side.
2. Check the resistance between the ECALL relay box assembly connector (ESO- terminal) and (ESO+ terminal).
  OK: 1.5 - 70 ohms
3. Check the resistance between the ECALL relay box assembly connector (ESO+ terminal) and body ground.
  OK: No continuity
  
  Q: Is the check result normal?
  
  YES: Replace the ECALL relay box assembly (Refer to ECALL RELAY BOX ASSEMBLY ).
  
  NO: Go to Step 5.
STEP 5. Resistance measurement at the ECALL relay box assembly connector (ESO-, ESO+ terminals).
1. Disconnect the ECALL relay box assembly and the ECALL speaker connector, and measure at the wiring harness side.
2. Check the resistance between the ECALL relay box assembly connector (ESO+ terminal) and the ECALL speaker connector (terminal No. 2).
  OK: The resistance should be 2 ohms or less
3. Check the resistance between the ECALL relay box assembly connector (ESO- terminal) and the ECALL speaker connector (terminal No. 1).
  OK: The resistance should be 2 ohms or less
4. Check the resistance between the ECALL relay box assembly connector (ESO+ terminal) and body ground.
  OK: No continuity
5. Check the resistance between the ECALL relay box assembly connector (ESO- terminal) and body ground.
  OK: No continuity
  
  Q: Is the check result normal?
  
  YES: Replace the ECALL speaker (Refer to ECALL SPEAKER ).
  
  NO: Repair the connector(s) or wiring harness.
STEP 6. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Check again if the DTC is set in the TCU.
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check the DTC.
  Q: Is the DTC set?
  
  YES: Replace the TCU (Refer to TCU ).
  
  NO: The trouble can be an intermittent malfunction (Refer to How to use Troubleshooting/inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).