THE PEUGEOT CAR CLUB OF VICTORIA

FELINE FOCUS
Mark Besley discusses some of the
joys of owning late model Peugeots
Multiplexing and Lighting
WAY back in May 2007, I wrote
about fitting a towbar to my
307 and the fact that the electronics
cost more than the actual towbar.
My experience and that of others has
prompted the question from some as
to why I couldn’t have simply wired
up the trailer plug by tapping into the
wires running to the taillight assembly.
Effectively this would simply put the
trailer lights in parallel with the vehicle
lights and should work fine. After all, this
is how trailer plugs have been wired up
forever isn’t it?
The problem with this approach is that
the multiplexing is sophisticated enough
to actually check the current draw and
detect faults in the lighting circuits and
bulbs. When you put two globes in
26
TORQUE 909
parallel, you draw twice the expected
current. The car’s systems would detect
this as a fault and log it.
This has the advantage that the car is
capable of checking bulbs, so you no
longer need to back into a parking space
in front of a shop window to check the
operation of your brake lights.
The car’s electrical system appears to
be passing a small current through the
globes all the time, even when they are
“off”. By doing this, a faulty globe can
be detected at any time when the car
is running. If a globe is blown, the car’s
systems detect the open circuit and log a
fault which can be accessed via the car’s
menu.
Here’s an example of the log showing a
blown parking light globe.
307 Brake Light Switches
I have written about this component
before - I’ve had one replaced (or was
it two?) and I believe that many 307
owners have had more than this. The
brake light switch doesn’t just turn on the
brake lights - it is a fundamental input
to some of the car’s systems that need
to know if you have your foot on the
brake pedal - these include ABS, stability/
traction control, auto transmission etc.
Failure of the switch can typically lead to
things like “ABS fault” warnings.
Unfortunately there seems to be a design
fault which leads to fairly frequent
failures of this switch and until now I
hadn’t heard of any solution other than
a simple replacement. Paul Watson, who
had mentioned his concerns about this
component to me previously, recently had
his fourth brake light switch failure after
90,000 km in his 307.
The good news is that there now
seems to be a better solution to the
problem. In Paul’s car they fitted a 308
switch (presumably a better-designed
component) rather than another 307
one. This required an adaptor loom
which adds to the cost somewhat (he
was told $100 plus). Fortunately Paul’s
was covered by his extended warranty.
However if you have been plagued by
brake light switch failures in your 307, this
may be a good option. I would certainly
consider this for my 307 if I have any
trouble with this component in future.