Headlight wiring

Electronic systems, stereo and Holden iQ, wiring, it all goes here....
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iefbr14
Posts: 38
Joined: Sun Oct 18, 2015 11:31 am

Headlight wiring

Post by iefbr14 »

I have come to notice how small the gauge wiring is for the headlights (high/low beam). I have not done the gauge wiring/load/voltage calculations, so I am not speaking in terms of mathematics, just common sense visual observations.

Compared to older cars, the wiring is several gauges smaller. Are they running closer to tolerance to save money? Because a halogen bulb is a halogen bulb...should draw the same current whether it is in a 2014 PPV or a 1982 Celebrity.

I compare the headlight wire gauge to even the MAP LIGHT wiring from my 1998 Oldsmobile (non 9C1, non 9C3, obviously), and the map light wiring for that 0.25amp (3watt) bulb is much thicker.

I guess the thinner wiring must still meet spec and cost savings, but will it cause a problem if I decide to splice in, for example, LED fog lights? (Don't ask why would I want to...my root question remains: with wiring as thin as it is, would splicing in to it smoke the wires?)
smwalker
Administration Staff
Posts: 2201
Joined: Mon Jul 29, 2013 1:44 am
Location: Azusa,CA

Re: Headlight wiring

Post by smwalker »

Yes it's amazing the small wires they are using. If you were to add anything you would want to use a relay where the draw would be miniscule. I did up some relay harnesses for the fog lights and I spliced into the parking lights circuit because I did not even want to risk adding in a splice into the headlights circuit that could possibly add resistance on a circuit that I am sure must be at it's max with amps.

So yea relays for sure.

If you want to use fogs as DRL's remember the headlight circuit drops down in voltage (not sure how much) but that could possibly mess with a relay on that circuit.

And looking at your history I think you got a 14. I am working on adapting the work I did on the 11-13 to the 14+. but you can get an idea of the relay here:

11-13 Fog Light Wiring
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White
BIG_GREEK
Posts: 174
Joined: Mon Sep 12, 2016 12:18 am
Location: Delmarva

Re: Headlight wiring

Post by BIG_GREEK »

These cars and most other cars today use a CAN (Controller Area Network) system. It uses a central module with multiple other modules to control different points of the vehicle. Think of the headlights as a module. There is one power and one ground (thicker gauge) and the rest are "trigger" wires (smaller gauge). So yes, in essence it is a relay activation. So that one power power wire feeds all of that light's power (turn signal, parking lights, headlights, etc...). Makes for less weight and less wires.
"God created Police Officers so Fireman could have heroes!" - My late Father

2014 Phatom Black 9C1 (Toy)
2000 VW Jetta TDI (Daily 420k miles)
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