Delaying the Dim

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!

Contact: www.jaycar.com.au