Checking & changing a headlight bulb

Part 1. Preparation and safety

Objective

• Check and change a headlight bulb.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• There are many types of headlight bulbs available. Always make sure that you replace a bulb with one of exactly the same type. Otherwise, change both lights at once, so they always show the same intensity in lumens.
• Sealed beam units require that the whole unit be replaced when one filament has failed. If the reflector in the lamp unit shows signs of internal blistering, that also indicates that you must change the unit.

• If both lights operate but are not bright when switched on, start the engine to see if this solves the problem. The battery may be in a poor state of charge. Another explanation is that the system may have a bad ground connection. This would have to be checked with a DVOM.
• Touching a new halogen bulb with your fingers can leave some greasy residue from your fingers on the outer surface. This can cause the bulb to burn out very quickly. If you inadvertently touch the bulb, clean it with an alcohol-based substance. Do not use gasoline or paraffin to clean the bulb.

Part 2: Step-by-step instruction

1. Check headlight operation
   Assessing headlight operation is always best carried out in a low light environment. Switch the vehicle headlights on to low beam, then switch to high beam. Check that the main beam indicator on the instrument panel is operating. Note the change in the intensity of the lights. If one of the lights does not operate that headlight will need replacement.
2. Identify headlight type
   Determine the type of lamp fitted to the vehicle, and obtain a replacement. Many vehicles today are equipped with halogen type headlights. These are twice as powerful as older sealed-beam units and need to be handled carefully. Always follow the manufacturer’s handling instructions.
3. Access the lamp socket
   Unplug the electrical connector at the back of the lamp unit. On most vehicles it is not necessary to remove the lamp unit from the vehicle. Unscrew the bulb-retaining ring.
4. Remove and replace the old bulb
   Remove the old bulb and replace it with the new one. Handle the new bulb only by its base or, if supplied, by the card cover. It is very important that you never touch the surface of the bulb with your fingers, as this will cause it to burn out very quickly.
5. Replace the headlight unit and test
   Replace the unit and the retaining ring or bulb assembly, and then re-plug the connector. Switch on the lights again to confirm that they are both operating correctly.