Your Monday Maintenance Tip: Checking Lights and Direction Indicators

Lights are easier to check on a dull day or when daylight is fading.

SIDELIGHTS Two white at the front; two red at the back. Should be bright and of equal intensity. Look closely at the rear lights to see if there is a dim glow from the brake lights, turn indicators or high-intensity fog lights — this may mean a poor earth to the car body on the nearest sidelight. If the front sidelights are small bulbs set in the headlight reflector these may be dim — these little bulbs tend to overheat and go black inside. Not a MOT fail point as such if they are both equally dim, but it's best to replace them.

HEADLIGHTS Put the headlights on dipped beam. Both should shine with equal brightness — failure to do so means a bad electrical supply or earth at that bulb. The reflection from the lights on a wall or garage door should show the two beams pointing slightly down to the left and level.
There are adjusting screws or knobs behind each headlight, but unless a beam is so far out of line as to cause a hazard, it is probably best to leave adjustment to the MOT tester, who will usually use a beam-setter to set them spot on. Switch to main beam and make the same check —

REAR FOG LIGHT(S) Switch on the high-intensity red rear light(s) — your headlights need to be on dipped beam. If fitted, fog lights must work, so must the interior 'tell-tale' light on the instrument panel.

DIRECTION INDICATORS Turn the ignition on and operate the indicators. Check that there is a flashing 'tell tale' light on the instrument panel. Check that front and rear indicators are flashing.
The flash rate should be between 30 and 90 per minute. If it's just under 30 it may speed up once the engine is running, though not if the flasher unit is an electronic rather than a mechanical unit. Side repeater indicators on the wings must be working if fitted.

HAZARD WARNING LIGHTS With the indicators off, switch on the hazard flashers, checking for the warning light and/or tick inside. Walk round the car to ensure that all four hazards are flashing, and that no other lights are glowing dimly. Switch off hazard flashers.

BRAKE LIGHTS Get a helper to operate the foot brake while you check the brake lights. Again, both brake lights must be equally bright, with nothing else glowing. Switch off the ignition.

LIGHTING REPAIRS If a light isn't working, chances are the bulb is blown. Bulbs are standard items, so replacement is easy. Indicators and rear red hazard lamp bulbs are 21 watt; brake light and rear tail light are usually a 21 and a 5 watt combined into one bulb. This only fits one way round to ensure the brake light is the more powerful. If it doesn't slip in easily, don't force it! Ensure that the offset pins match the slots in the bulb holder.
Front sidelights are either small bulbs set in the headlamp reflector, or larger bulbs (around 5 watts) under separate covers. Headlight bulbs come in various fittings and types, so take the old bulb along when buying a replacement. Access to the bulbs is gained by either unclipping the bulb-holder from the back of the light housing (usually after removing a cover) or by use of a number 2 Pozidriv (cross-head) screwdriver to unscrew the coloured lens from the outside.

If you have a vehicle handbook, it may show the correct procedure for removing and fitting bulbs. Other reasons for a bulb not lighting may be broken or badly corroded wiring. If one lamp lights up another, check for broken or corroded wires or a damaged lamp-holder and replace them. Many rear light units are mounted on a printed circuit board. If the circuit strips corrode, a new unit will probably be needed.
Front sidelights are either small bulbs set in the headlamp reflector, or larger bulbs (around 5 watts) under separate covers. Headlight bulbs come in various fittings and types, so take the old bulb along when buying a replacement. Access to the bulbs is gained by either unclipping the bulb-holder from the back of the light housing (usually after removing a cover) or by use of a number 2 Pozidriv (cross-head) screwdriver to unscrew the coloured lens from the outside.
If you have a vehicle handbook, it may show the correct procedure for removing and fitting bulbs. Other reasons for a bulb not lighting may be broken or badly corroded wiring. If one lamp lights up another, check for broken or corroded wires or a damaged lamp-holder and replace them. Many rear light units are mounted on a printed circuit board. If the circuit strips corrode, a new unit will probably be needed.

LENSES & REFLECTORS Headlamp reflectors must be bright and not obviously misted, tarnished or corroded. The headlamp lens should not have any hole or a crack that could let in water. All plastic lenses covering the other lights should be the correct colour and not excessively faded.

 

Courtesy of 2Pass