Reversing lights are not generally a legal requirement but they are useful.
They serve two purposes - to warn other road-users you are about to reverse,
and to provide light if you are reversing in the dark.
is a simple one, consisting of one or two rear light units
operated by a
, so if anything goes wrong it is easy to check. On most
cars the switch is mounted on the
box and it is operated automatically when
reverse gear is selected. If the lights were added after the car was made, the
switch may be a manually operated one mounted on the dash.
One of the most common problems is a blown bulb. To test it, remove it from
its holder and connect it across the
with a short extension
wire. If the bulb lights up the fault lies elsewhere in the circuit.
First check that the bulbholder and wiring terminals are clean and bright.
If there is any corrosion, clean it up with wet-or-dry paper then refit the
bulb and retest.
If the bulb still fails to light, the
may have blown. You should also
suspect a blown fuse if two reversing lights go together.
In many cases the fuse protecting the reversing lights also covers other
accessories (see your car handbook to find out which ones). If none of these is
working, renew the fuse and test again. If the fuse blows as soon as you test
it there is a
somewhere - it may be easier to get an
auto-electrician to trace it.
If other components protected by the fuse are still working, then you need
to check the rest of the circuit using a test lamp.
on and remove the feed wire to the
to stop it
overheating. Select reverse gear or the 'R' position on an automatic.
Clip the test lamp to a good earth point and probe the live terminal in the
bulb holder. If the test lamp lights,
is reaching the bulb. If the bulb
has a separate earth lead, the fault must lie in that.
To check the earth run a short wire from the bulbholder earth to a point on
the car body. Refit the bulb and check again. If the bulb works, renew the
If no current was reaching the bulb-holder you will have to check back along
the rest of the circuit.
Find from your workshop manual the colour and route of the reversing wires.
Carefully probe the wire along its length. In most cases the wire will
disappear into the main loom where you can't get at it. If you find the fault
is inside the loom you can
it by splicing in a new wire.
If there is no current in the wiring, check the gearbox switch. On a manual
car there will be two switch terminals. On an automatic there will be four, two
of which are for the
circuit and should not be disturbed (unless you
are adjusting the switch - see sideline, left). Check your manual to find the
correct terminals for testing.
It may be easier to raise the car on
stands. Then turn the ignition on
and select reverse gear. Connect the test lamp to earth and probe one terminal,
then the other. If the lamp lights on both terminals, the fault is in the
wiring between the switch and reversing lights. If the lamp fails to light at
all, check the wiring between the fuse and switch. If the lamp only lights on
one terminal, the switch is either broken or needs adjusting.
To replace a reversing light switch, disconnect the wiring and either
unscrew the switch or, if a locknut is used, release this. Replace the switch
in reverse order, then adjust it.
Adjusting the switch on a manual gearbox
To adjust the locknut type switch, connect a circuit tester across the
Select reverse gear and slacken the locknut (right). Screw in the switch
until the tester just lights, then do up the locknut.
Other switches are adjusted by unscrewing the switch completely and
adding or subtracting
(right). The setting is correct when the tester
just illuminates as the switch is fully tightened.
Adjusting the switch on an automatic gearbox
Some automatic gearbox switches are adjustable. The basic method for
adjusting is described here, but you should always check with your workshop
manual for the exact procedure.
Start by identifying the four switch wires and terminals, then
disconnect them. Move the gear
to the drive position. Slacken the
locknut and unscrew the switch from the gearbox a few turns.
Using a circuit tester with its own power supply (not a test lamp),
connect it across the two reversing light terminals. Slowly screw the
switch in until the light goes out. Mark the switch and gearbox with a dab
Now connect the circuit tester across the two inhibitor terminals. Screw
the switch in further until the tester lights up again, and mark this
position on the gearbox in line with the previous mark you made on the
switch. Screw the switch out until its mark is exactly halfway between the
two marks on the gearbox (below), then tighten the locknut.
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Reversing is one of the most difficult manoeuvres you can perform with your
car, especially at night. The manoeuvre is made much safer and easier if your
car has a pair of reversing lights, which come on automatically when you engage
reverse gear to light up the area behind your car.
Although they are considerably more complicated than manual gearboxes, with
control and operating functions in addition to the gears, modern automatic
transmissions are less likely to give problems than their manual