[Mk2] [Generic] Headlight problem. Help appreciated

[aj.extreme]

Right

Fitted quad frog lights a few months ago and wired them so that all four hold H4 bulbs. These were working absolutely fine until a week ago

My issue, turn the dipped beam on and nothing except the main beam indicator on the dash will light up, I can hear the relay up front click and all fuses are fine.

Push to turn the highbeams on and all four light up no problem and the dash indicator gets brighter.

Again with flashing the lights, all works as expected.

All other lights are working as they should, just no dipped beam.

I have not changed anything since fitting them and after having a good poke around can't see anything obvious. Any pointers much appreciated

Initial thoughts are the headlight relay in the frunk, would this still click if it was faulty?

[shinny]

I would say you have a bad switch on the indicator stalk.

The fact all the main beams turn on tells you the relay and fuses are fine. The fact the high beam indicator lights up at all says at least one of the low beam filaments is ok. The fact it lights up when the low beams should be on tells me the switch that should be grounding the low beam filaments isn't doing it's job. Given you're running twice the designed current through it, it may not be a surprise it's burned out.

If you're good with wiring diagrams you can come to the same conclusion I have from this: http://shinny.co.uk/toyota/MR2_SW_1993_ ... litusa.pdf

[aj.extreme]

Yeah looks plausible, didn't even think that it maybe a grounding issue and looks like the headlights work on a switched earth. And yes it seems that I should have run a new earth to cope with the extra load, I will investigate a little further now I know where to focus

Many thanks

[Peter Gidden]

And yes it seems that I should have run a new earth to cope with the extra load, I will investigate a little further now I know where to focus

Have you not added relays to cope with the doubling in current draw, or still using exisiting wiring?

[aj.extreme]

I am using the stock harness peter, wired an extra H4 bulb holder into the harness. I can see where this is leading

[Peter Gidden]

I am using the stock harness peter, wired an extra H4 bulb holder into the harness. I can see where this is leading

Errrrrrr, i'd be rewiring pretty quickly!

You need to use the original wiring as signals to switch relays.

I've done several for Rogue quad lights.

[aj.extreme]

Yeah simple enough, would pulling a 12v feed from the battery be ok? What would I need to do with the ground connections on the stock loom?

Still need to fix the initial problem tho but assuming that's something burnt out in the switch

This is my track car so not used very often, since installing the headlights they have maybe seen 1/2 hours use so no problems from here on in

[shinny]

TBH, the 15A fuses and thus the wiring *should* be able to cope with the double current, but it's no surprise you're pushing the switch gear hard and the 20 year old contacts have said no.

However, once you're rewiring, you might as well wire it directly to the battery.

[aj.extreme]

TBH, the 15A fuses and thus the wiring *should* be able to cope with the double current, but it's no surprise you're pushing the switch gear hard and the 20 year old contacts have said no.

Makes total sense, I will track the fault down now I have a better understanding.

[shinny]

Well, I've got wiring mods for my rogue lights (http://www.imoc.co.uk/forums/viewtopic.php?t=167468) and very happily draw for all four filaments at once from the standard wiring and fuses... however I am not switching double the current like you are. My setup has lasted coming up two years now. That's a lot longer the the 30min yours lasted

As it happens, Peter warned me on my thread about doubling the current through the switch gear (although it didn't actually apply to me)

[aj.extreme]

Very true

I am fairly new to auto electrics and have a lot to learn but think I'm gonna take a look at the switch and rewire/replace and then fit relays to power the headlights using the loom as the switching signal.

I much prefer having all four beams lit up, especially on the setup I have installed

[shinny]

I'd strongly suspect you'll be replacing the indicator stalk rather than repairing the switch. Also, don't replace the switch with all four bulbs still hooked up. Sort out the rewiring or disconnect two of the bulbs BEFORE replacing the broken switch

[aj.extreme]

Just ordering up the parts needed, am I right to assume I need to wire in a blade fuse between the battery and the relays?

[shinny]

Just ordering up the parts needed, am I right to assume I need to wire in a blade fuse between the battery and the relays?

YES!

Put the fuse as close to the battery as possible. I recently had a power cable for my amp short onto the body in the frunk before its fuse. Not only did it burn a hole in my chassis, it also made the car cut out dead on the motorway... I know the installation from the previous owner was pretty shaky but I'd still not recommended risking a repeat.

[aj.extreme]

Yeah thought as much and looking at 14awg power and ground wire? Should be sufficient?

[shinny]

What's that good for... 60 amps?? The pair of filaments you'll be running off the wiring only draw 10 amps.

[aj.extreme]

Just been on Google and read a few articles recommending 10gauge but that's what I used to have running power to my amps etc seems a bit overkill

I'll go take a look in maplins over the next couple of days see what they have

[aj.extreme]

SELECTING WIRE SIZES FOR USE IN LAMP CIRCUITS

Use only stranded wire, never solid (household type) wire, in automotive applications.

Wire gauge selection is crucial to the success of a circuit upgrade. Wire that is too small will create the voltage drop we are trying to avoid. On the other hand, wire that is of too large a gauge can cause mechanical difficulties due to its stiffness, particularly in pop-up ("hidden") headlamp systems. The headlamp power circuit ought to use no less than 14-gauge (2.5 mm2) wire, with 12-gauge (4.0 mm2) being preferable. 10-gauge (5.2 mm2) can be used if bulbs of extremely high wattage are to be used, but it's usually overkill. Be sure to pick a kind that flexes easily if yours is a hidden-headlamp system. Do not fail to use the large wire size on both sides of the headlamp circuit! Voltage drop occurs due to inadequate grounding, too! you will only sabotage your efforts if you run nice, big wires to the feed side of each headlamp, and leave the weepy little factory ground wires in place. Most factory headlamp circuits run the too-thin ground wires to the car body. This is an acceptable ground--barely--on a new car. As a car ages, corrosion and dirt build up and dramatically increase resistance between the car body and the ground side of the vehicle's electrical system. It takes little extra effort to run the new, large ground wires directly to the battery Negative (-) terminal or to the metal housing of the alternator, and this assures proper ground.