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Home / DTC / B1492 — HRA: Part E1m1 (Left headlamp range adjustement motor) has

B1492 — HRA: Part E1m1 (Left headlamp range adjustement motor) has

Detailed page for trouble code B1492.

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Code

B1492

MERCEDES-BENZ B — Body

HRA: Part E1m1 (Left headlamp range adjustement motor) has

Brand: MERCEDES-BENZ
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Left headlamp range motor (E1m1) fault or internal failure
  • Mechanical binding or stripped gears in the headlamp adjuster
  • Open, short or high-resistance wiring between motor and HRA module
  • Corroded or loose connector at the motor or lamp assembly
  • Insufficient power supply or missing ground to the motor circuit (fuse/relay issue)
  • Faulty HRA/headlamp control module or software anomaly

Symptoms

  • Left headlamp leveling does not change when commanded (manual or automatic)
  • Headlamp aim remains fixed or asymmetric between left and right
  • Dash message or warning related to headlamp leveling/HRA
  • Audible clicking or no sound from adjustment motor when actuation commanded
  • Adaptive or automatic beam leveling fault or reduced visibility at night

What to check

  • Read and record freeze-frame and all related fault codes with a capable scan tool
  • Attempt to command left headlamp range motor via diagnostic tool and observe operation
  • Visually inspect left headlamp connector and wiring for corrosion, pin damage, or water ingress
  • Check fuses and relays for the headlamp/HRA circuits
  • Measure battery voltage at motor supply pin during activation (should be near battery voltage when driven)
  • Check ground continuity from motor ground pin to chassis ground

Signal parameters

  • Supply voltage to motor when commanded — approx. vehicle battery voltage (~12 V)
  • Control signal type — switched power or PWM from HRA module (check with scope or manufacturer data)
  • Motor current draw while operating — should increase when moving (abnormally low or zero suggests open circuit; very high suggests stall)
  • Position feedback voltage/resistance/encoder value — should change as motor moves
  • Resistance across motor terminals when de-energized — compare to known-good side if available

Diagnostic algorithm

  1. Connect diagnostic scanner, record B1492 plus any other codes and freeze-frame data. Do not immediately replace parts.
  2. Clear codes, then reproduce fault by commanding the left headlamp range motor while monitoring live data. Note whether motor attempts to move and any feedback values.
  3. Visually inspect the left headlamp connector and wiring harness for damage, corrosion, water ingress, or crushed wiring. Repair connectors as needed.
  4. Check fuses/relays related to headlamp leveling and verify proper operation.
  5. With connector disconnected, measure supply voltage and ground at the motor connector while commanding the motor. If no supply or ground, trace wiring back to module/fuse/relay.
  6. Measure motor coil resistance and compare to the right (good) motor specification or manufacturer values. If open/short or significantly different, suspect motor failure.
  7. If power/ground are present but motor does not run, bench-test the motor by applying correct voltage (observe safety and manufacturer guidance). If motor does not operate or draws excessive current, replace motor/adjuster assembly.
  8. Inspect and test mechanical movement of the adjuster for binding, stripped gears, or foreign objects; replace lamp assembly or adjuster mechanism if damaged.
  9. If motor and wiring test good, check HRA/headlamp control module outputs with a scope or meter; consult wiring diagrams and consider module replacement or software update per manufacturer guidance.
  10. After repair, clear codes and verify correct operation through diagnostic actuation and a road/night check to confirm proper beam leveling.

Likely causes

  • Failed or seized left headlamp range adjustment motor
  • Mechanical obstruction or damaged gearing inside the lamp adjuster
  • Connector corrosion or wiring open/short to the left motor
  • Blown fuse or poor ground affecting motor drive

Fault status

⚠️ Status
Left headlamp range adjustment motor E1m1 — malfunction detected (electrical or mechanical fault).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

B1491 B1493 B1240 B2416
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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