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DTC B254B: CAMERA output voltage fault
 
 
 
 
DTC SET CONDITION
When the camera-ECU detects any of the conditions below, the ECU sets DTC No. B254B.
  • Power supply voltage to a camera remains 5.2 V or less for at least 5 seconds.
  • Power supply voltage to a camera remains 7 V or more for at least 5 seconds.
noteWhen DTC No. B254B is set, the segment, which corresponds to a defective camera, is displayed in blue.
 
 
TROUBLESHOOTING HINTS
  • The front-view camera may be defective
  • The rear-view camera may be defective
  • The side-view camera (LH) may be defective
  • The side-view camera (RH) may be defective
  • The camera-ECU may be defective
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector (power supply lines to a camera short to power supply or ground)
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Voltage measurement at camera connectors (ACCN, ACCR, ACCS and ACCY terminals)
(1) Disconnect the all camera connectors, and measure at the wiring harness side.
(2) Press the electric motor switch to turn on the power supply mode, and then check the power supply lines to a relevant camera.
(1) Check the voltage between the front-view camera connector (ACCN terminal) and ground.
OK: 5.5 - 6.5 V
(2) Check the voltage between the rear-view camera connector (ACCR terminal) and ground.
OK: 5.5 - 6.5 V
(3) Check the voltage between the side-view camera (LH) connector (ACCS terminal) and ground.
OK: 5.5 - 6.5 V
(4) Check the voltage between the side-view camera (RH) connector (ACCY terminal) and ground.
OK: 5.5 - 6.5 V
Is the check result normal?
Go to Step 3.
Go to Step 2.
 
STEP 2. Check of short to ground circuit in ACCN, ACCR, ACCS and ACCY lines between camera connectors and camera-ECU connector.
(1) Disconnect the all camera connectors and camera-ECU connector, and measure at the wiring harness side.
(1) Measure the resistance between the front-view camera connector (ACCN terminal) and ground.
OK: No continuity
(2) Measure the resistance between the front-view camera connector (ACCN terminal) and camera-ECU connector (except ACCN terminal).
OK: No continuity
(3) Measure the resistance between the rear-view camera connector (ACCR terminal) and ground.
OK: No continuity
(4) Measure the resistance between the rear-view camera connector (ACCR terminal) and camera-ECU connector (except ACCR terminal).
OK: No continuity
(5) Measure the resistance between the side-view camera (LH) connector (ACCS terminal) and ground.
OK: No continuity
(6) Measure the resistance between the side-view camera (LH) connector (ACCS terminal) and camera-ECU connector (except ACCS terminal).
OK: No continuity
(7) Measure the resistance between the side-view camera (RH) connector (ACCY terminal) and ground.
OK: No continuity
(8) Measure the resistance between the side-view camera (RH) connector (ACCY terminal) and camera-ECU connector (except ACCY terminal).
OK: No continuity
Is the check result normal?
Replace the camera-ECU (Refer to ).
Repair the connector(s) or wiring harness.
 
STEP 3. Voltage measure at camera-ECU connector (ACCN, ACCR, ACCS and ACCY terminals)
(1) Connect camera connectors one after the other, and then measure at the power supply terminal of the corresponding camera-ECU connector by backprobing.
(2) Press the electric motor switch to turn on the power supply mode.
(3) Connect the front-view camera connector.
(4) Check the voltage between camera-ECU connector (ACCN terminal) and ground.
OK: 5.5 - 6.5 V
(5) Connect the rear-view camera connector.
(6) Check the voltage between camera-ECU connector (ACCR terminal) and ground.
OK: 5.5 - 6.5 V
(7) Connect the side-view camera (LH) connector.
(8) Check the voltage between camera-ECU connector (ACCS terminal) and ground.
OK: 5.5 - 6.5 V
(9) Connect the side-view camera (RH) connector.
(10) Check the voltage between camera-ECU connector (ACCY terminal) and ground.
OK: 5.5 - 6.5 V
Is the check result normal?
Go to Step 4.
Replace the failure camera (Refer to ).
 
STEP 4. Recheck for DTC.
Check again if the DTC is set in the camera-ECU.
(1) Erase the DTC.
(2) Press the electric motor switch to turn the power supply mode from "OFF" to "ON."
(3) Check if DTC is set.
Is the DTC set?
Replace the camera-ECU (Refer to ).
The procedure is complete.