Headlight wiring upgrade

Adam · Site Admin Joined: 04 Oct 2001 Posts: 682

Factory gemini headlights are nothing spectacular, on most models you are looking at a 60/55w sealed beam headlight running directly off the headlight switch.

This setup leads to a lot of voltage drop and also the sealed beam units are at best marginal, at worst they are woefully inadequate.

A better solution are H4 insert type headlights (where the bulb is seperate from the reflector. With these you also have the option of fitting bulbs of a higher watter, such as 130w/55w items (130watt high beam, 55watt low beam).

However the factory wiring isn't particularly great and the factory headlight switch will not appreciate having in excess of 20 amps flowed through it.

So the solution is to upgrade both the headlights and the wiring.

You'll need;
2 x 30amp (or greater) 12v automotive relays
20 metres of at least 30amp wire (or 15 metres of >30am wire and 5 metres of 15amp wire)
A whole bunch of suitably large male and female spade connectors
Four circle type earth connectors
Two H4 solder-on type connectors
Two Inline fuse holders with 30amp fuses

I also used:
One soldering iron
Some flux-cored solder
Aftermarket battery terminals

The wiring diagram would like something like this

Start by locating your headlight power wires underneath the dash, on my TD they were pretty easy to find, both were red wires, one with a blue trace and the other with a yellow trace. The go into the left hand side of the blue connector under the dash near the steering column, where there are four 10 pin connectors (white/blue/orange/green) in a row. Keep in mind this may be different on your car...

Get yourself a probe type test light (under $10) and go hunting.

For the sake of neatness I decided I would run the wiring along the factory loom and retape it afterwards, it was kinda fun trying to push 6 wires through the already full firewall rubber seal.

Again for neatness's sake (and because it seemed logical) I (actually it was my mate, Hugh) mounted the relays in the factory relay box.

For those who want it step-by-step;
1. Locate factory headlight wires
2. Disconnect battery
3. Run two (30amp++) wires from battery, down left wiring loom, under dash, up right wiring loom to relay box.
4. Run two wires (two 30s, or a 30 and a 15) from the left hand headlight, down left wiring loom, under dash, up right wiring loom to relay box.
5. Run two wires (either 30 or 15 amp)from the relay box down the right hand wiring loom to under the dash near the factory headlight wiring.
6. Cut the factory wiring for the headlights and attach it to the two wires you ran in step 5.
7. Wire up the headlight connectors, making short earth leads out of 30amp wire... I attached the left one to one of the regulator mounting bolts. About now you should decide which wire is high beam and which wire is low beam.
8. Wire up the relays, ensuring you connect the right wires to the right plugs.
9. Mount the relays in the relay box.
10. Fit the fuses to the two power wires and attach the wires to the positive battery terminal.
11. Double check your wiring.
12. Re-attach battery.
13. Test run headlights.
14. Tape up wires onto factory loom.

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

Several optins are available for different models so I'll start at the beginning. The semi-sealed 7" round upgrade will suit TX - TC's, some TD vans/wagons and base model TE's with round lights. Semi-sealed rectangular conversions are also available for all other TE's and TF's without the SL/X front. TF SL/X's and TG's can do the wiring conversion and just change the globes as they are already semi-sealed. TD's with the square lights, unfortunately can't be upgraded without changing to the round lights of the TX & TC, which is a bolt in fit. However doing the wiring upgrade will result in longer switch and wiring life and will increase the brightness of the globe somewhat due to less voltage loss.
On to the wiring.
A simpler running of the wires is possible if your wiring is still in good nick. A headlight relay with two circuits and inbuilt fuses is available rather than two separate relays. This then only requires one power wire and one earth. The less joins you have, the less chance of faults. Unravel the tape around the headlight nearest the relay box and run the three wires to the switching/input side of the relay, they should be long enough. From the relay run your six heavy duty (5 or 6mm) wires (two high beam, two low beam and two earth), one of each to each headlight. For the light on the opposite side, route the wires in front of the top of the radiator but be careful of the bonnet catch. Then run a power and earth wire (again 5 or 6mm) from the battery to the relay box and connect them to the relay. Route them with the headlight wires in front of the radiator and tape them up with electrical tape like factory. For added protection, put a fuse in the power wire as close to the battery as neatly possible.

Adam · Site Admin Joined: 04 Oct 2001 Posts: 682

After your heads up on the dual circuit fused relay I went to my local auto-elec supplier (I'm there at least 3 days a week) and chatted to him about them, he flatly refused to sell me one (even though it was on the shelf) saying that they had an extremely high rate of failure.

Tooleeda · tinkerer Joined: 04 Oct 2001 Posts: 93

For the fuse holders I would reccomend at least 60 amp fuse holders with the screw down ends, (not the half twist type) or an appropriate rated fusible link wire.

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

We carry the "New-Era" brand and haven't had one back yet.
Our own local mobile Auto Elec. also buys and uses them.
As with everything, you get what you pay for. Using a cheap single relay will probably result in mid to long-term failure also. Particularly with something as critical as headlights, you don't want them failing on a dark, wet, twisty mountain road.

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

If you DO put in a bigger fuse holder, you still only want to put in a 30amp fuse. The last thing you want is a current overload of 50amps to melt your 30amp wiring before ever blowing your 60amp fuse! Er on the side of caution, always use wire rated higher than the accessory you're powering, and use a fuse equal to or slighly less than the wire rating. That way, if anything goes wrong, your fuse blows before your your wiring starts melting. Better still, invest in a self resetting circuit breaker. This way, if there is a problem, your lights will flash on and off, allowing you to a least pull over safely.

gabz20 · rice boy Joined: 24 Mar 2002 Posts: 43

umm can someone tell me why my lights flicker on and off when i drive down the road at night?, maby i have a wire earthing out or something. really pissing me off!@#

gemie chick · tinkerer Joined: 06 Oct 2001 Posts: 94

in case anyone was wondering where to get non sealed h4 lights from.. you can run around your local wrecker and almost any car with the same shaped lights(there are many) will fit ya gem...just make sure they are not sealed beams... non sealed ones pretty much always say H4 Halogen on the lens.. if in boubt unplug em' and see if the globe comes out.. most of them its a simple matter of just putting them in the gem mounting bracket and plugging them in. a few examples are the celicas, 323, laser, most vans, and many more. the brightest i have seen are from a mazda B2600 4WD. in my TG i put ones, dare i say it, from and older f**d laser.. i had to grind off some brackets from behind them but it still took about 15 mins. if the glue that holds the lens onto the reflector melts silicone fixes it fine.. these lights are about a billion times better than stock sealed beams, and there is the bonus of the parking lights being inside of them. with just the parkers on ya gem looks evil! this also means that u can ditch the parker\indicator lights from the bumper, put spotties there and get the TE clear parking lenses and put clear indicators on ure TG.
i hope this helps
Greg

Stock TE · backyard mechanic Joined: 12 Mar 2002 Posts: 853

do you mean run the new wire parallel to the old wire (both connected) or change the wiring completly (disconnect old wire)

Steven · rice boy Joined: 13 Aug 2002 Posts: 31

If your finding your lights failing and returning, toss in another thermal protection relay, under dash between coulumn and kick panel (TD's). When I upgraded my TD S with H4's 90/1??, standard wiring held up for the 6 years but thermal only was good for 18mths

Stock TE · backyard mechanic Joined: 12 Mar 2002 Posts: 853

To save time use the original headlight plug for the switch wires.

Tex · tinkerer Joined: 13 Feb 2003 Posts: 163

As Stock TE said if you use the headlight power wiers from the right hand headlight its close to the relay box and saves you locating the headlight wiers. Just remember to tape up the left hand wiers!

Stock TE · backyard mechanic Joined: 12 Mar 2002 Posts: 853

Go to http://groups.msn.com/IsuzuPlace to see it.