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Autopapyrus · Peugeot Boxer (2nd generation)
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Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Peugeot Boxer (2nd generation): Headlight Wiring and Relay Diagnostics

On a 2016 Boxer, the low and high beams are powered through relays and fuses. The steering column switch controls them through the body control module. The fault usually comes down to a bulb, a corroded connector, a fuse, a relay, or a damaged wiring harness. Work from the simple to the complex: bulb, fuse, relay, power and ground, then wiring and switch. An exact fuse box layout for your trim level was not found in open service materials, so the procedure below is general. Check the location of each relay against the label on the box cover and the diagram in the owner's manual.

Difficulty: Medium Time: 1-2 hours Steps: 13 Tools: multimeter, 12 V test lamp or probe, screwdriver and socket set, fuse and relay assortment, contact grease or contact cleaner, jumper wire with a 10 A fuse

Part

  • 🔩 Depends on the diagnosis. Typical candidates: 12 V automotive relay (4-pin, 30-40 A), low beam and high beam fuses, halogen headlight bulbs, bulb sockets (connectors), headlight switch on the steering column. Part numbers are not given. To avoid a mistake, choose the relay by the markings on the old one's housing and choose bulbs by the type listed in the owner's manual
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes AutoFix (online) and 1 more. See manuals →

Step by step

13 steps
  1. Identify the symptom: one headlight is out or both, and whether only the low beam, only the high beam, or both modes fail. One headlight out almost always means a bulb or connector. Both out at once means a shared circuit: a fuse, relay, switch, or ground.
  2. Check the battery voltage (normal is 12.4-12.8 V with the engine off) and the condition of the terminals. Low voltage and corroded terminals cause dim lights and false faults.
  3. Remove the bulb from the headlight that isn't working (access is from the engine bay, through the rear cover of the headlight). Inspect the filament and the glass. Check continuity with a multimeter, or swap in a known-good bulb. Do not touch the glass of a halogen bulb with bare hands.
  4. Inspect the bulb socket for signs of melting, darkened or corroded contacts, and oxidation. Replace a melted socket. Clean corroded contacts and treat them with contact grease.
  5. Locate the fuse boxes. One is in the cabin under the dash on the driver's left, and the other is in the engine bay (usually next to the battery). The diagram is printed on the box cover or given in the owner's manual. Find the low beam and high beam fuses (separate for the left and right headlights) and the headlight relays.
  6. Hold each fuse up to the light to inspect it, and check it for continuity with a multimeter. Replace a blown fuse only with one of the same rating. If the new fuse blows right away, there is a short to ground in the circuit. Trace it along the harness. Do not install a higher-rated fuse.
  7. Test the relay. Remove it and check the coil for continuity (usually pins 85-86, resistance of roughly 50-100 ohms). Apply 12 V to the coil and confirm that the power contacts (30-87) close with a click. For a quick check, swap it with an identical relay from another circuit, such as the horn, if the markings and pinout match. If the fault moves with it, the relay is bad.
  8. Check the relay socket for power. The power pin (30) should have constant battery voltage. The control pin should show voltage or ground when the lights are switched on, depending on the circuit design. If there is no control signal, the cause is upstream: the switch, the body control module, or the harness.
  9. Check the voltage at the bulb connector with the low or high beam on. It should be close to battery voltage (a loss of no more than 0.3-0.5 V). If there is no voltage, follow the wire back to the relay and fuse. If there is voltage, check the ground: test continuity from the socket's ground contact to the body. Resistance should be close to zero.
  10. Inspect the wiring harness near the headlights, where it passes through bulkheads and frame rails, and near the hood hinges and any rubbing points. Typical problems are broken or chafed wires, corroded connectors behind the headlight, and moisture and corrosion at the ground points on the body. Clean the ground points to bare metal, tighten them, and protect them with grease.
  11. If all circuits up to the connector are fine but the control signal doesn't arrive, check the headlight switch on the steering column. Test all switch positions and look for a signal at its output. Repeated intermittent failures are often caused by worn switch contacts.
  12. If the problem is in the body control module, or you need to read fault codes, you need a diagnostic scanner that supports Peugeot and Citroen. The OBD diagnostic port is in the cabin under the dash on the driver's left.
  13. After the repair, turn on the low beam and high beam, and flash the high beam. Confirm that both headlights shine evenly. Check the beam aim and adjust it.

Common mistakes and warnings

  • Before removing bulbs, sockets, or relays, turn off the ignition and the lights. Do not install a higher-rated fuse, because it creates a risk of a wiring fire. If the problem persists after replacing the bulb and fuse, and the harness is damaged or you suspect the control module, take the vehicle to an auto electrical shop. Faulty lights are a safety hazard when driving at night, so do not drive the vehicle after dark until the fault is fixed.