So you might be wondering, "Why would someone with a Sil80 give a crap about onevia wiring?" Well, the simple answer is that I don't. Personally I think onevias are for kiddyfiddlers!
Just kidding.
(Not really...)
Seriously though, I did spend a bit of time recently trying to wire 180 headlight motors into a Silvia loom. From what I understand, people with the full 180 car and engine bay loom (or at least the loom out of a halfcut) will just wire in all of the factory components and hope it all works. On the other end of the scale I have heard about others who simply have a switch to put the headlights up, and another to put them down.
I'm not a huge fan of either of these solutions, so I designed and built a circuit that operates exactly the same as the factory wiring, but can be built from components available at Jaycar or DSE (or recycled from a car or halfcut).
We’ll start with the headlight motors themselves. Each one has five wires, two thin and three thick. The colours seem to vary depending on the year of the car they came out of, but they all share a few common features that should make the wires fairly easy to identify.
The easiest wire to identify is the ground wire. It’s one of the three thicker wires and it’s plain black.
The extend wire is also thick, and from my experience is always solid brown. When the ground wire is grounded and this wire is connected to 12 volts, the motor will rotate to the ‘full extend’ position (i.e. the headlight would be all the way up) and then stop.
The extend signal wire is thin, and is usually brown with a coloured stripe along it, usually white or yellow. While the headlight is extending, this wire outputs 12 volts. Please note: it is not protected by a diode so if you accidentally try to power the motor off this wire, it will generally wreck part of the PCB inside the motor, and just make the motor rotate constantly.
The retract wires are thick, and usually purple with a white stripe, or black with a white stripe. These work the same as the extend wires, they just make the motor rotate then stop 180 degrees around from the ‘full extend position’.
The retract signal wire is the one left over. It is thin and usually orange, sometimes with white dots along it. This wire outputs 12 volts while the headlight is retracting. Fortunately, it is protected by a diode, so you can hook 12 volts to it without worrying about cooking the PCB.
In summary:
The aliases refer to the wiring diagrams below.
This first diagram is the simplest and cheapest way to get the headlights working off the indicator stalk.
While this works, it does have a few limitations. Firstly, it requires the ignition to be on for the headlights to retract. Some really anal rego places might have a problem with this. Secondly, the headlights will come on as soon as they are turned on. In a real 180, they don’t come on until the headlights have fully opened.
To solve these two problems, I had to use more than twice the relays, and a few diodes. The nice thing about this setup is that it’s functionally identical to the wiring in the 180. Actually, that’s not completely true. It is missing the headlight ‘extend’ button that can be found to one side of the steering wheel in the 180, but since the Silvia doesn’t have this button, I didn’t think it was worth including.
A couple of things to note about wiring it up:
- Both of the extend power wires should be connected together and then connected to the EXT output of the circuit.
- Both retract power wires should be connected together and then connected to the RET output of the circuit.
I’m not totally sure about this next bit, so if you have any corrections, please PM me or send an email to
cypher1024@hotmail.com
Cut both of the low-beam headlight wires (just near the bulb) and connect the car sides of them to the ‘Headlight IN’ wire of the circuit. Then connect the bulb side wires to the ‘Headlight OUT’ wire of the circuit.
In the 88 Silvia I examined, the passenger's-side low-beam 12V wire was green with a yellow stripe and one dot. On the driver's-side the wire was just green.
So, how does it all work?
Well, when the headlights are turned on, the coil on the Direction relay is energized and connects the EXT wire to the battery. The headlight begins to extend and the ExtSig wires of both motors start outputting 12 volts.
This power energizes the ‘Bulb power’ relay and disconnects the headlight bulbs from the headlight power. It also energizes the Latch relay which then ‘latches’ on and holds the ‘RetPower’ relay on.
Eventually the motor reaches full extension and the ExtSig wires no longer provide power to the ‘Bulb power’ relay and the headlights turn on.
As soon as the headlights are turned off, the ‘Direction’ relay routes battery power to the ‘RetPower’ relay which is still energized. This causes the headlight motors to start retracting and the RetSig wires to output 12 volts. These energize both the breaker relay and Latch relay, this way power is maintained to the ‘RetPower’ relay.
When the headlights reach full retraction, the RetSig wires no longer supply 12 volts and the Latch and Breaker relays are both turned off simultaneously. This then turns off the ‘RetPower’ relay.
This way, the circuit doesn’t draw any power when the headlights are off.
Any questions can be directed to me via PM
Enjoy!
- cypher
Edit: Primer on relays
Diode info
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It's come to my attention that the headlight motors can probably be controlled with a single relay. I.e.
I've yet to test whether or not they draw any current when they're fully retracted (thus flattening your battery when your car's off), but I think they don't. Word to your mother!
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