STEP 1. Check headlight relay (LOW) connector A-32X, ETACS-ECU connector C-410 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
STEP 2. Check the wiring harness between headlight relay (LOW) connector A-32X (terminal 1) and ETACS-ECU connector C-410 (terminal 6).
STEP 3. Using scan tool MB991958, check whether the DTC is set again.
Check again if the DTC No.B1E25 is set in the ETACS-ECU.(1) Erase the DTC.
(2) Turn on the low-beam headlights.
(3) Check the DTC is set.
Is the DTC set?
Replace the ETACS-ECU. The trouble can be an intermittent malfunction (GROUP 00 - How to use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).