DRL's on a 70 GT!

[wrench459]

The PO removed the wiring from the rad. support forward to the headlamps.
Simple rewire right?
Yeah sure right funny how working on cars will keep you humble.
Anyway wired the headlamps no problem so far.
Turned on the master switch and you guessed it no headlamps.
hummm checked the white and yellow wire with a voltmeter.
12 volts on one and .30 volts on the other.
Oh a bad ground ok easy stuff no prob right?
Found two wires coming out of the fuse box..both brown Dang theres the ground problem. NOT!!
I ran out of time working on this problem tonight so the Battery was disconnected.
One of the wires was a 20 guage wire which I thought was the headlight relay ground.
REPEAT after me three times
I own a Antique
I own a Antique
I own a Antique
So now whenever the ignition key is in the run postion the headlights turn on.

[2 Fast 4 U]

Then it's time for new wiring

[wrench459]

Had some spare time tonight to look at the headlights.
And for the life of me I don't remember that the headlights would come on when flipped over with the key on.!!!
I do recall that the engine would not shut off till the master switch (headlamp) was off.
And it didn't help matters that the 69 wiring diagram is wrong!!
Oh well I'm just going to put a toggle switch in for the time being, since the whole frontend is being replaced this winter.
Question why did they put 12 gauge wire on the micro switch to control the field side of the relay?
Dang Germans and there over engineering.

[baz]

guess thats why there are so many of these almost 40 year old cars out there

[wrench459]

Yeah you see them on the road every day.

[ungermm]

On my 72 GT restoration project I just rewired the headlights. Man were they in bad shape. All three wires for both headlights from the lights back to were they come through next to the radiator were brittle and corroded. The wire sheathing just flaked off revealing wire that kind of resembled horse hair. It wasn't so hard to rewire, just took longer than I thought. The brown 12 gauge ground wires are attached to the body behind the brake booster. You might want to test the your grounds there and then also at the headlights. I was surprised how expensive wire has become. I decided to use brown and white 16 gauge wire from standard household extension cords. My thought was that the vinyl sheathing is very flexible, the wire is a finer quality, and the cost is about 1/4 of auto wire. Easy enough to change at this point in the project if this type of wire is not an adequate substitute. Jerry

[namba209]

Jerry, I wouldn't go any less gage on the wire that's there originally. The designers made that decision for you with a bit of overkill for safety reasons. If you can get some extension cord of the correct size you'll be o.k., and you're correct, the finer wire inside is better.

[wrench459]

Curiosity got the best of me so I grabbed the low current probe.
Yellow/Black wire is caring 200 ma of current.
Got to love them Germans 12 guage wire to carry 2ths of a amp.

[namba209]

Dan, Not near my schematics, still in KS, 'til tomorrow. Red/Black is the power to the headlight relay switch, through the microswitch, IIRC. If so, JJ Wheatley acknowledges overkill on all the microswitch wires and 18 gage wires will do the deed nicely.