An interior light courtesy delay unit does just
what its name suggests – it keeps the interior light(s) on for a short time
after you get into the car, before then gradually dimming them out. The result
is more convenience and it’s also a small luxo upgrade that works well.
The Kit
The electronics kit that lets this happen is the
Jaycar Courtesy Light Delay Kit Mk II, which costs AUD$18.95 and is cat no
HB-6015. The catalog entry suggests that a box will cost you extra but our kit
came complete with the box.
If you can solder and recognise components, this
is a very easy kit to build. The component locations are shown on the printed
circuit board and there’s only a handful of components to fit anyway. Use a
multimeter to measure component values (don’t just rely on colour or other
codes) and make damn’ sure you fit the polarised components in the right way
around.
Installation
The first step is to locate one of the courtesy
light door switches.
Take off the trip panel behind the switch and
examine the wiring. In nearly all cars you’ll find a single wire that leads to
the switch. When the door is open the wire is earthed, so completing the circuit
and switching on the light. However, in some rare cases you might find a
different system, one which is covered in detail in the kit instructions.
Because earthed-to-switch-on is by far the more common of the systems, we’ll
concentrate on that one.
Strip some insulation off the wire leading to the
door switch and solder a new wire to it. Wrap the join in insulation tape.
Direct this wire to where you want to mount the
box containing the kit. In our case we mounted the box under the dash and so the
wire from the courtesy light switch passed along the sill panel. We lifted a
trim panel to feed it through.
You’ll also need an ignition-switched 12V supply.
This is not for the expected use – it doesn’t power the kit. Instead, this feed
will cause the courtesy light to automatically switch off when you start the
car. The kit instructions don’t show this approach; instead they connect to the
tail-lights so that when the lights are switched on, the courtesy light goes
off. But it’s easier and – we think – more convenient to trigger this with the
ignition. We used a multimeter to find a 12V ignition-switched source near the
underdash fusebox.
Finally, you’ll also need an earth (ground) wire
connected to the chassis.
You’re now ready to temporarily wire the system up
to see that it works. Connect the wire from the door switch to the positive (+)
door switch input on the PCB. Connect the negative door switch input to ground.
Connect the 12V switched ignition input to either of the inputs marked
‘tail-lights’ and connect the other of the tail-light inputs to ground (so there
are two ground connections). Make sure that the back of the PCB cannot contact
anything (like the chassis!) and then get in and close the door. The courtesy
light should stay on for about 10 seconds before fading off. You can change this
delay time by altering the position of the trim-pot on the PCB.
The board can then be placed in the box...
...and the box stuck with double-sided tape in a
convenient place and the wiring tidied.
You’re finished!