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DTC B1E12 Low Beam Light(LH) Open Load or Blown Error
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
DIAGNOSTIC FUNCTION
DTC B1E12 will be set when the headlight (Low-beam) (LH) bulb is burned or the headlight (Low-beam) (LH) circuit fails.
 
 
TROUBLE JUDGMENT
DTC B1E12 will be set if the ETACS-ECU detects a blown headlight (Low-beam) (LH) bulb, or an open circuit between the ETACS-ECU and the headlight (Low-beam) (LH).
 
 
TROUBLESHOOTING HINTS
  • Blown headlight (Low-beam) (LH) bulb
  • Headlight (Low-beam) (LH) bulb installed improperly
  • Malfunction of headlight (Low-beam) (LH) socket and headlight (Low-beam) (LH) unit
  • The headlight (Low-beam) (LH) control circuit fails
  • Malfunction of the ETACS-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Bulb check <Vehicles with halogen headlight>.
Check whether the headlight (Low-beam) (LH) bulb is blown or installed improperly.
Is the check result normal?
Go to Step 2.
Replace or reinstall the headlight (Low-beam) (LH) bulb.
 
STEP 2. Check of open circuit in HLOL line between the headlight assembly (LH) connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 3.
Repair the connector(s) or wiring harness.
 
STEP 3. Check of open circuit in ground line between the headlight assembly (LH) connector and body ground.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if DTC B1E12 is set in the ETACS-ECU.
(1)
cautionTo 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).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Erase the DTC.
(3) Turn on the headlight (Low-beam).
(4) On completion, check that the DTC is not set again.
Is the DTC set?
Replace a headlight (LH). Then go to Step 5.
The trouble can be an intermittent malfunction (GROUP 00 - How to use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
 
STEP 5. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if DTC B1E12 is set in the ETACS-ECU.
(1) Erase the DTC.
(2) Turn on the headlight (Low-beam).
(3) Check if the DTC is set.
Is the DTC set?
Replace the ETACS-ECU.
The diagnosis is complete.