Headlight Harness

Mysterytrain · 09-29-2005, 12:12 PM

After driving home for two hours Sunday night with my brights on and not having one driver flash me to turn them off I've decided it was time to ditch my sealed beams and go with a pair Cibie, relays and some moderate wattage bulbs 55/100s or 90/100s. Thinking more towards the 55's because i don't want to give the law another reason to pull me over! I did my usual research here on the subject and also on the net but still have a few questions. My 78SC has 1.5mm wires in the harness feeding the headlights. That DIN gauge is rated at 17amps and is equal to a 15 gauge SAE wire [if we had such a thing] so I will round down to 16 gauge SAE rated at 16 amps. Now I know that each 100watt bulb will draw about 8 amps so the existing harness should be fine because I don't intend to go any higher then that. However, I because I'm anal I am tempted to make a new harness with some beefer gauge wire [if I can find the correct colors.. remember, I'm anal]. So, my questions are...How many conductors in the harness? I count 4, high, low,left turn and left parking? From what I have gathered from various posts, the harness enters the bucket, connects to the headlamp and also a small harness that feeds the parking lights and side markers by going back out of the headlight bucket..is this correct? Someone also mention using a 964 headlight harness..so is that harness the same configuration but of a heavier gauge? Also, if anyone has an SC harness laying around that I could use as a model let me know.

Ryce Stallings · 09-29-2005, 01:34 PM

Pelican has the wiring diagrams on line. You are correct about the routing of the wires into the headlights and then on to the turn signals.

I looked into the 964 front harness idea and came back with a dealer cost of $1000. Apparently the front harness includes more than just the lights. Let me know if you find out differently.

I have 100 watt H-4s and I see indications of heating at the three prong connector to the headlight. The SC wire or the connector itself is perhaps only just handling the 100 watt bulb!

Mysterytrain · 09-29-2005, 02:44 PM

Thanks, Ryce ..I punched a 964 harness part number into Pelican and came up with $300. I guess I could look into a wrecked car for the part. Do you know if they went to a higher gauge wire and a relay system for the 964? The connector seems to me to be a bigger problem then the OE harness wire size. Once, you add some corrosion and oxidation to the connector you get the high resistance there you pull more current and make more heat.

Ryce Stallings · 09-29-2005, 04:00 PM

I bought my car in Andora. It had four hood mounted Monte Carlo rally lights on it. It had a relay for them but the headlight switch became toast after a while. The connector for the headlights could have been damaged at that time. I looked or new connectors to splice into my harness but the all have smaller wire than the original.

Those lights were very cool...turn all six lights on and it was daylight again!

Mysterytrain · 09-30-2005, 08:37 AM

ok, a shameless self serving bump for the morning crowd

RoninLB · 09-30-2005, 09:47 AM

I run 130/100w Narva w/Cibie non DOT. Aiming is the game not the output.

Parking lights is not part of the immediate circuit.

derkpitt · derkpitt's Garage

I looked at an early 964 harness once, wire size was the same as my 88. If your going to add relays, then you would only need wiring from them to the lights. Tap off the factory wiring at the fuse box for controlling the relays.
Here's a curd photo of the circuit.

Mysterytrain · 09-30-2005, 11:50 AM

Ron..I think the parking light wires are encased in the same harness with the low and high beams. The harness comes up into the buckets and then splits the parking light conductors out [handy for the city light option].
Derk, that was my plan..basically to make a new factory type harness from the relays to the headlights and remove the OE harness for safe keeping. Rather, the pulling the harness out a discovering what I was going to need to make I'm trying to get my ducks in order and make the new harness in advance.

RoninLB · 09-30-2005, 01:19 PM

Quote:

Originally posted by Mysterytrain

Ron..I think the parking light wires are encased in the same harness with the low and high beams.

that sounds familiar. I must have sliced, added new wires/removed old and wrapped in the high end 3m black tape.