DRL System

Moore Family
of Arizona

Daytime Running Light System:

This is a planned project - not yet completed...

Factory Spec Option:

My GTS already has a provision for a DRL capability with the addition of an optional relay, however it only operates the front fogs whenever the car is running - I don't really like this mode.

My Desired Operation:

I think true DRL's should be operated automatically based on need: dusk, low ambient light (e.g. tunnels, heavy cloud), rain or by drivers choice and should always include rear and side markers as well as front fogs for good all round visibility. There should be some driver indication that DRL's are active rather than normal headlights. It should be possible to leave the DRL system in the desired state and have it engage upon starting the car. I think it should also be easy to disable the DRL mode using the normal driving controls.

Implementation:

I plan to replace my front fog light switch with a switch body from a headlamp switch. This will give me a 3 position turn switch instead of the 2 position push switch. The new switch will control my automated DRL system as follows:

Position 0 = Off - The DRL system is disabled.
Position 1 = Auto - Marker Lights & front Foglights auto-on when its dark enough while the car is running (off until actually running & variable auto-on sensitivity).
Position 2 = On - Marker Lights & front Fogs on when actually running.

My expectation is that I would leave the system in the Auto position (1) normally

I have the design already completed for a 1990+ configuration only.

Dashboard Indicator:

When the new fog switch is in position 1 or 2 and main light switch is in positions 0 or 1 the existing green 'marker light' indicator will come on in the pod. This will go out whenever the ignition is off or when the headlamp switch is in position 2.

I like this functionality because:

- I can turn off the DRL mode whenever I want
- I can still force the fogs/driving lights to go on whenever I want
- I will always have front/side/rear markers also on in any active DRL mode
- I can leave the switch in any position I want and allow the ignition to switch it
- The dashboard indicator reminds me when DRL mode is active (as with HL 1 mode)
- 'Flash to pass' still always works (at least the driving lights flash on)

The only thing I think is less good is that now the adjacent headlamp & front fog lamp switches have the same operating mode (3 position twist). It would be possible to relocate (say to the bottom left position) - but the fogs and reset switch also have a similar operating mode in the stock configuration (push momentary/push lock)

The features I describe utilize the existing fog light relay for fog light switching and one extra relay to switch the marker lights, they are both controlled the same way. A true single DPST relay could also be used instead, but they are rare. There is also the variable light level detection module that operates these relays in the auto mode - I have not decided where/how to mount this yet and some aspects of the design (luminous hysteresis and temporal hysteresis need to be finalized).