Flash-to-Pass Modification for Roadsters
This is how to get a “flash to pass” feature on early Mk1s. '94 and '95
models implemented an inferior system from the factory that keeps the
headlights up for 3 seconds before lowering them.
Go to Maplins and buy a 2.5A high current diode.
Part info 1N5408 Rectifier Diode (Part No QL87U)
Squirm your head down under your dash and find a big white connector (some Miatas have a green connector) shaped like this:
Work with the male connector.
Bend both leads close to the diode (cutting is not necessary) to form a |_| shape.
Locate the Red with White stripe wire and the White with Black stripe wire.
Push the ends of the diode into the connector next to the wires with
the diode’s white stripe sticking in next to the White/Black wire. It
should go nearly all the way in and make contact with the metal parts
in the connector.
Test by pulling on the bright light switch. The headlights should go up, flash, and go back down!
For UK cars apparently this is a help
On my 1990 UK car and have found the wiring layout and colour coding is different.
You still have to fit the diode between two wires but it would not work
as advised in the original instructions so after a little check with my
multimeter I discovered that the diode has to be fitted between the
Red/white wire and the White/blue wire with the stripe on the diode
going to the White/blue wire.
Just for reference the Red/white wire is for the headlight flash and
the White/blue wire is for raising the headlights the diode connects
the two hence a headlight raise and flash.
The wiring is different due to the UK day running lights fitted but if the diode is fitted as I have said it works fine.
More info with pics
I just popped out to my car, removed the top cowl over the steering
wheel unplugged the appropriate plug and took some pics. All of ten
mins, I could have done the mod in the same time [ I must admit I’ve had
these apart a few times]
Pic 1 general view across the centre of the wheel with the cover
removed. The bit you are looking for is the whitish bit top right at
back of column centre
Next shot shows the plug in close up
On the bottom side of the plug is a release clip. push it in and
remove the plug. This is what mine looks like, you can clearly see the
diode, and take note of the band around the body, this must be fitted
this way round between the white/black tracer and Red/white tracer
Give it a go