Fisher Fury R1 Indicators

When I originally built my car in 2007, I optimised the lighting circuit design as much as possible but used an 'off the shelf' hazard light switch and a standard electronic flasher unit for the indicators and hazard lights. The hazard light switches are complex and expensive. The main issue with the electronic flasher unit is that the flash rate is dependent on load. As soon as you connect LED bulbs instead of filament bulbs, the flash rate changes to indicate a bulb failure.

To get around many of these issues, I've designed my own flasher circuit with the following requirements in mind:

LED Lights

I want to use these LED lights I bought on eBay. They are both white and orange and so they can serve as both indicators and daytime running lights. The existing DRLs I have fitted will be removed.

These lights have three wires; black = ground, red = white LED, yellow = orange LED.

I tested these in daylight and they are plenty bright enough, though more directional than the filament bulb indicators they replace.

Bespoke Housing

I've 3D printed bespoke housings for my new indicators and day-time running lights. These are painted to match the bodywork and lacquered. You can read more about the design process on my diary pages. Bascially, I wanted to reuse the existing holes in the bodywork.

Indicator Switch

I've designed the circuit to use switches that don't switch any high currents. This means I can use much smaller and lighter switches. For the indicators, I'm using a tiny on-off-on switch mounted to the paddle shift, using a 3D printed housing. I'm also using 0.2/7 equipment wire as it's carrying a tiny current.

Hazard Switch

I've designed my circuit to use a simple on-off switch to control the hazards. This means I have a much greater choice of switches and can use a much simpler one.

Flasher Unit

I've designed a flasher unit to have a fixed rate flash and so it will work with any bulbs. A timer is used to generate the fixed flash rate.

Audible Indicator

Because my car is so loud, I'm using a tiny 5V buzzer mounted on my PCB and driven by the Arduino. I have the option to remotely mount this if need be.

Hazard Switch

I've designed my circuit to use a simple on-off switch to control the hazards. This means I have a much greater choice of switches and can use a much simpler one.

Daytime Running Lights

What I'm planning are not daytime running lights in the strictest sense as they are basically powered by turning on the side lights but one requirement I have is for them to be disabled on each side when the corresponding indicators are on. This is because I'm planning to use a combined LED light that has both white and orange LEDs.

This will be achieved by cutting the power to each DLR, when the corresponding indicator is powered. This means both sides if the hazards are on.

Electronics

I mapped out the logic required for each indicator and daytime running light. This is duplicated for left and right but some of it is obviously common to both sides. I then rationalised the logic but, it still left a fairly complex circuit if using logic gates alone to implement the design.

It just makes a lot more sense to use an Arduino Nano to do all the timing and logic. It's very cheap, very compact and these things are super reliable. I can use a dc-dc convertor to power it at 5V dc.

Writing the code to deliver the functionality required was very easy.

From a 'black box' perspective, the PCB module looks like this.

Power

I obviously don't want this powered up all the time, so the power to the PCB (and Arduino) will be from the indicator power feed (via ignition switch) and the permanent feed via hazard lights switch. Both will power the PCB via diodes, so effectively acting as an OR logic gate.

The hazard light switch feed will also be an input into the Arduino (HAZ_S). So when the hazard lights are activated the PCB is powered up and the indicators switched on.

Inputs

All the inputs will be 12V dc and interfaced to the Arduino using a quad opto-isolator.

Outputs

The outputs will drive P-channel MOSFETs, to provide 'high side' switching. Most common MOSFET circuits work by pulling the load to ground but this doesn't work in a vehicle with a common earth through the chassis. I'm using FQP27P06 MOSFETs which are rated for very high currents.

PCB

Wiring

Because the logic for the DRLs now resides on the PCB mounted behind the dash, I need to run new wires to each front DRL. Because the currents are so low, I can use thin, low-current wiring. The smallest wires I use in the Fury for powered things like LED lights is 16/0.20 0.5mm² rated at 11A max. I can reuse the existing earth wires.

Note: As per my original build, all the connections are crimped and solder and covered in heat-shrink where it makes sense. All the connectors are also wrapped in a waterproof rubber cover and tie-wrapped. It's more effort but I've not had a single electrical issue with any wiring on my Fury since I built it.

The most time consuming part of this whole exercise is undoing lots of 'spiral wrap' on my wiring, adding the new wires and then wrapping it all up again! :-(

With the hazard switch, flasher unit and the exisiting indicator switch being removed, a lot of wiring is gone, to be replaced by a much simpler setup.

Hazard Light Switch

Three wires go to the hazard light switch now. A red wire carrying +12V, an orange wire returning it when switched on and a white wire to flash a 12V indicator bulb inside the switch.

Connectors

I currently have an 8-way connector with 6.3mm spade terminals, which connects all the lighting and earths to all the lights attached to the bonnet. This makes it really easy to remove the bonnet if need be. Rather annoyingly, there is only one spare unused pin on this connector because I run two earth wires through it (left and right sides have independent earths for reliability).

Rather than mess with this, I'm simply going to add this 2-way connector for the DRL feeds, next to the other one.