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Spotlight Light Bar

Constructing/Wiring the Light Bar | Vehicle Wiring

When you go off-roading at night in the wet, headlights can often get covered in mud after just a few hundred yards, its annoying and a hassle to keep having to clean mud off headlights. For this reason I decided to make a removable spotlight bar using a standard roof-rack roof bar.

I bought some Thule roof bars for the Surf second-hand so I just needed to find some suitable spotlights. I wanted to mount my spotlights under the roof bar (between the roof and the roof bar) because this way the roof bar will still be usable if required and the spotlights will be protected from low branches etc. The space between the roof-bar and the roof was only 85mm, so the plan was to get 4 or 6 small spotlights. I did not find many small enough to fit that gap, and in the end went for two pairs of thin rectangular driving lights from Halfords. They are designed for the boy-racers out there with slightly blue lenses (apparently gives a "brighter, whiter light") but they look very well made and will easily fit:

They come with 55w halogen bulbs so the wiring for all four lights will need to handle at least 19 amps (watts / volts = amps), but I want the option of upgrading the bulbs to 100w so I will ensure the wiring can handle at least 38 amps in total.

CAUTION: If you don't have a basic knowledge of vehicle wiring then I would not attempt this job. You can easily melt wires and could cause a fire if you accidentally short out a 12v car battery.

Tools/Equipment Needed

  • Two pairs of Ring 55w halogen driving lamps (from Halfords)
  • Self-tapping screws
  • 17amp Wire
  • 27amp Wire
  • High current connector 2 way 75amp (Durite part: 0-012-02)
  • Switch body on/off single illumination (Durite part: 0-780-11)
  • Switch rocker single illumination (Durite part: 0-779-01)
  • Switch lens work lamps green (Durite part: 0-792-10)
  • Cable protector, electrical tape, zip-ties, spade connectors, scotch locks
  • Cross-head & flat-bladed screwdrivers
  • Wire cutters & strippers
  • Electrical crimping tool
  • Voltmeter

Constructing/Wiring the Light Bar

First, I attached each of the four lights to the underside of the roof bar using two self-tapping screws. I attached the earth connector from each spotlight to one of the two screws. The roof bar will not be earthed to the chassis but this saved me running earth wires as well as live wires along the length of the bar (I can take an earth feed from the end of the bar).

Most spotlights come with nut/bolt attachments, so if you don't want to have a bolt right through your roof bar you will need some additional self-tapping screws.

My original idea was to feed all the wires inside the bar, but this proved impossible - I could not get the wire to feed through the bar past the spotlight mounting screws that were now inside the bar. I eventually gave up and decided to run the wires externally. I used some spade connectors, plastic cable protector, a bit of electrical tape and some zip-ties to ensure all the wires were tidy, and ran all the wires to the left side of the bar (the side that will be on the passenger side of the vehicle). I used seperate lengths of 17amp wire for the live wire on each spotlight.

I then combined the four 17amp live wires down to two 27amp wires, and attached two 27amp wires to the end of the bar for earth feeds. I then attached these four wires to the male side of a two-way connector. My light bar is not going to be a permanent fixture, so I did not want to run permanent wires (my light bar wires will run into the passenger side through the door seal and attach to a connector that will be permanently wired into the cab.).

This 2 way high current connector. It comes with 2 sets of male/female connectors - 1 set for thinner wire and 1 set if you are connecting thicker wire or multiple wires.

 
     

Right: Finished bar showing connector.

Below: Finished bar showing wiring and the black plastic cable protector.

 
     

Vehicle Wiring

I wanted the light bar to be controlled by the existing main-beam switch, but with a switch in place to enable/disable the light bar.

This is the switch, rocker, bulbs and lenses (these bulbs and lenses are only sold in packs of 5).

 
     

First of all I installed and wired up the main light-bar switch. I removed a coin holder from the dash and installed the switch there (I had to cut the hole a bit bigger to get the switch to fit).

I wanted the switch to be lit when the other dash lights were on (rather than being lit when switched on) so I took a dash light positive feed from the back of the rear window demister switch.

The switch illumination circuit also required an earth, so I just attached it to the earth wire on the fog-light switch.

See Upper Dashboard Removal for details of how to access the dashboard wiring.

 
     

I then removed the plastic surrounds from the steering column to gain access to the wiring. I used a voltmeter to identify which wire was positive when main beam was on - in my case it was the red wire with green bands (A).

I attached another wire to this wire using a scotch lock and fed it to the switch.

Then I attached another wire to the remaining terminal on the switch and fed it behind the dash to the passenger side of the vehicle so it came out behind the glove compartment.

 
     

Then I removed the passenger side of the dash which includes the glove compartment.

See Lower Dashboard Removal for details of how to dismantle the passenger side lower dashboard.

 
     
I then wired up the female side of the connector.  
     
Then I removed the plastic trim on the passenger door pillar - just pop out the bit nearest the rear of the vehicle and then it can be carefully removed.  
     

I fed the wires from my female connector behind the plastic trim and down behind the dash to come out behind the glove compartment.

I am happy for this connector to be visible here as my vehicle is more a working/utility vehicle and it's the easiest place for it. You may want to hide it somewhere or make your light bar a permanent fitting.

 

I already fitted a second leisuire battery to my surf anyway so I already had a suitable high-amp feed into the cab to power the lights. Even if you don't do this you will need to run a high-amp cable direct from your battery to run your spotlights - you can't just connect to a live feed behind the dash or somewhere - the wire almost certainly will not handle the amps that the spotlights will require.

All that is left now is to wire up your spotlight relays (relays almost always come with a set of spotlights) to your spotlights, your live power feed, a chassis earth, and your switch. One thing not to forget is to ensure the circuit has suitable fuses in it.

I mounted my relays and did all wiring so it would be hidden behind the glove compartment.

Disclaimer

I have taken a lot of time to ensure the information above is correct, but please remember vehicle manufacturers make alterations and design changes during the production run of a vehicle. No liability can be accepted for loss, damage or injury caused by any errors in, or omissions from, the information given above.

If you think any information is incorrect, confusing, misleading or incomplete, please feel free to contact me.


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