Modifying the lights system so the headlights only work with the ignition on
and/or taking the current load off of the Lights Master Switch (LMS)


Created: 13 november 2001 

Last updated: 13 november 2001 


Author/source: Jan van de Wouw, VIN#05141


As with all these modifications, do them at your own risk!
Work precise and concentrated, double check everything!

First get the materials needed:
-One or two Automotive relays, depending on whether you want to do one or both mods. Coil-voltage 12V,
contacts rated at a minimum of 10Amps Normally Open, preferably with an "eye"on the case to srew it in place.
-connectors (spades and scotch-locks) and a crimping tool.
-some wires, length according to where you want to put your relay(s)
-electrical tape
-at least SOME knowledge on electrics and wiring, even if only to understand what I'm writing...

Second make the wires to the LMS accessible, how you do this is your own choice, I did this mod when I had the center console out anyway.
If you have enough slack on the wires going to the switch, you can probably un plug is and either pull them out through the hole for the LMS,
or fold them back so you can reach them from under the dash.
When doing the Headlight modification it's neccesary to be able to reach the wires for the radio (LGW=LightGreen/White) or Hazard switch (G=Green) too.

If you have the wires in reach you need to decide which modification to perform, you can best do both of them at once,
allthough you "D"looses some of it's originality, it gaines in safety and comfort.

I'll describe both mods separately, but here's some info you'll need for either one:

There should be 5 wires going to/from the LM Switch (still connected to the wires!):
NU (Brown/Blue) = +12V Continuous
U (Blue) = +12V in second position: Headlights
B (Black) = Ground for backlighting
RO (Red/Orange) = +12V in First AND Second Position: backlighting
RG (Red/Green) = +12V in First AND Second Position: Perimiter Lights

Determining wire lenghts is easiest with the relay(s) installed, so screwing it/them down first is a good idea.
Make sure you can reach the connectors when istalled! I put mine beneath the console on the drivers side;
unscrewed a screw on the AC-ducting and put the relays on this screw.

In order for you to position the relays this "far"from the switch, in most cases you'll need to lengten the original wires to reach both switch AND relay.
When doing so, observe wire thicknesses and mak sure you allways use wires of the same thickness as the original ones. NEVER use any thinner wires,
doing so anyway MAY result in a meltdown or (ven worse) a fire when in use!
Make all connections stable, both mechanically as electrically end make sure to ahev everything insulated.

+++++

Taking the current load off of the LMS.

Cut the RG wire at some lenght from the switch, make sure you can still connect both ends to other wires!
The part coming from the switch needs to be connected to the coil of the relay, the part going into the harness gets connected to one of the contacts of the relay.
Now use a Scotch-Lock to splice a wire into the NU wire at the LMS and connect the other end to the second relay-contact.
Take a second Scotch-Lock and splice this one into the B wire at the switch, connect the still open end of the relay's coil to this wire.

You're done! The relay gets it's power from the switch, the load for the lights through the relay.
All the switch gets as load now is the current for the relay; about 0,1Amps, far less than the 4Amps the lights draw all together...

+++++

Disabling Headlights with the ignition in OFF-position.

Look above for the wire colors; cut the U wire far enough from the switch to be able to re-wire both ends.
Connect both wires to the contacts of the (second) relay. Wire one side of the coil of the relay to ground,
either by splicing it into the black wire at the LMS if you haven't done the other mod or by using a spade connector with a second spade on it at the ground connection on the other relay.

Now it's time to decide if you want your Headlights to be enabled in IGN-position II only, or in position I and II.
Personally I chose to enable them in both positions,; this resembles my other car...

If you want the lights enabled in BOTH positions, splice a wire into the LGW wire going to the radio, using a Scotch-Lock. Make the splice at the Harness side of the in-line fuse,
this way you can easily remove the radio without having to cut any wires.

For the lights to work only on IGN II use a Scotch-Lock to splice into the Green wire at the Hazard Lights Switch.

After doing either splice, connect the other end of the wire to the open end of the coil for the (second) relay.

If you've done all the way it should have been done, you shouldn't have any loose wires anymore and you should be able to check if all works as designed by me.
TEST THIS BEFORE REASEMBLING EVERYTHING!!!

With the INGNITION OFF, pushing the LMS to either position 1 or 2 should result in the perimeter lights coming on, a slight "click"can be heard at the first relay if you installed one.
If this happens you know your lights work and you can take comfort in knowing your LMS won't heat up any more.
Now turn on the ignition, depending on which splice you made you should hear a "click"in the desired position and with the LMS in position 2 the Headlights should come on.
Turning back the ignition should turn off the Headlights, but everything else stays on.

When something doesn't work this way DON'T PANIC! Just check everything again and use basic trouble shooting techniques to determine what went wrong.
If the lights worked as the factory made it when you started you should be able to successfully complete these modifications.

Good Luck!

JAN van de Wouw
Thinking Different... Using a Mac...
Living the Dream... Driving a DeLorean...

#05141 "Dagger"since Sept. 2000

------------------------------



Back to Technical Index

Home | Back Issues | Downloadable Files | Links | Subscribe
DeLorean FAQ Clubs and Events | DeLorean Mailing List FAQ


Copyright 2001  DMC-News
The legal fine print.
Comments, criticisms, questions:
webmaster(AT)dmcnews.com