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View Full Version : Wiring up trailer plug to WH



Dillzio
06-01-2008, 01:58 PM
Hey guys,

I just wanted to ask if adding the trailer plug to the taillight/indicator wiring is as easy as it is in earlier models?

I've noticed that by some type of voodoo magic, the car knows when a taillight or brake light has blown, and illuminates a warning light on the dash. I'm not sure how it works, but i thought that maybe it measures the circuit load or something so it knows when one of the bulbs isn't working.

Are there any diodes or anything like that that need to be added to prevent the piggy-backed trailer plug wiring from interfering with the car's electronics, or is there a specific place other than the taillight wiring that i should hook it up to?

cheers,

-Dylan

I've just spent about an hour fiddling around around in the boot with a circuit tester figuring out which wire does what. I also learned that my car's reversing lights are on the boot, so don't try to test if they're working if you're boot's up, it leads to much frustration! :banghead:

The wires i've figured out which are all behind the drivers side taillight are:

Black- Earth (duh!)
Tail Lights- Brown
RH Indicator- Blue
Reverse- Green
Brakes- Blue/red stripe
LH Indicator- Light Blue (further up the loom from where it branches off to the RH taillight, mine had a small white insulated male terminal on the end)

The one I couldn't figure out was brown with a white stripe, but i noticed that when the taillights are on the potential difference between the brown wire (taillights) and the brown/white wire (unknown) was about 7 volts. I thought that maybe the brown/white supplied a earth that went through a resistor so the parkers could run on 7 volts but i'm only guessing.

I think the voodoo magic of the car knowing when it's taillights/brakelights are out may be helped by the fact that the wires always have a very small current running through them, and if that current doesn't flow because the circuit is open at the blown bulb the computer would know the bulb is blown.

If anyone's done this before i would appreciate any feedback.

-cheers

planetdavo
06-01-2008, 04:17 PM
The "easy" way is to just buy the factory trailer harness from Holden, which simply plugs in, no cutting required, and wont upset anything.

Dillzio
06-01-2008, 04:18 PM
...oh, one more thing.

Have any of you used the clips that come with the trailer wiring kits before, the ones that just clip onto the wires you want to run your trailer wires off? I thought they seemed a bit dodgey, and that they might not make a tight constant connection, especially after they've aged a few years.

I thought it might be better to cut the wires, crimp electrical terminals to them, plug the terminals into each other and heat shrink any exposed contacts that are left?

-cheers

kingwalker
06-01-2008, 09:53 PM
just do as planetdavo said spend about $40. bucks and one minute there is your plug wired available in two diffrent outlet plugs i think:rofl::rofl: