Im puzzled with h4 plug install.

[tony rodaway]

Hello guys .
I'm have just fitted a new light bar and wanted to run off my main beam and switch.
The problem I have is I bought new h4 plugs for my headlights as looked corroded.
I snipped the 2 x red and green and 1xred and white easy enough or so I thought.
I connected the loom wires to my new plug and got no light on the side I reconnected.
I have tried every combination to get them on but nothing.
I have tested the loom wires independently with my test light and got battery voltage the same on all 3 wires .
This is the passenger side light I'm working on.
I compared the drivers plug with the passenger one and noticed the 2x red and green wires on the pass side are replaced with 1x red and green on the drivers side and 2 red and white in there place.
I just had the 2x red and green & 1x red and white loose as not connected to anything.
With my lights turned on I noticed the drivers side light works perfect low&hi beam until I connected the other passenger side light and the drivers side automatic turns to hi beam.
I still have no headlight on passenger side so thinking I had a bad bulb I connected the loom wires to my new plug and installed a new h4 bulb and still no headlight on the passenger side.
I have checked the 4 fuses for the headlights both sides and are all working perfectly.
There is no light bar or relay connected at this point just 3 wires .
I removed the battery to check I wasn't getting a bad wire connection but all fine
Not sure we're I went wrong just replacing a new plug with 3 wires.
I turned my headlights on and still with drivers side working perfectly I put my test light on the 3 loose wires and noticed I think was red&green wire and my drivers side turns to high bean .
So let me clarify at this point there is nothing connected just 3 wires and getting a battery reading from all 3 wires so bad wires is not the issue.
I'm stumped guys and ideas were I went wrong.
Never taken any pictures as just a simple 3 prong plug replacement with no complications.

Tell a lie now thinking about it when I was testing my relay I wanted the lightbar to work from my hi beams witch I achieved.
I couldn't figure out how to get the dash rocker switch to work with the connections on the relay.
I think it started to go wrong when I stupidly connected the highbeam connecter on the relay with the lightbar connection also on the relay but that seemed to be a big mistake.
So my steering wheel lever still works fine.
No blown fuses just a lot of noise in the relay.
I no how to connect all together as in rocker switch and relay but can't get My headlight to work.
I have swapped my headlights around and both bulbs still work.
Is there a fuse or relay that I may have fused that I'm missed out but can't see that as drivers light works perfect.
I don't want to take to a autospark as I want to fix myself with you help as you guys have never let me down so far.

 

[karl2000]

Hi, Tony what wires do you have to your H4 connector? Is it two negatives and one positive?

 

[tony rodaway]

Justt a simple 3 plug connector but either way i try I can't get it to work.
I have even put the 3 wires directly to the light prongs in every combination and still nothing.

 

[Tractionman]

Tony, for what it's worth Toyota lights are negative switched, maybe the new H4 plug with attatched wires is wired for positive switched so the wires are in the wrong position ?
Karl would be in more of a position to verify, maybe if you showed/explained the position of each of of those colours in the new plug ?
Oddly enough, I bought some of those, ages ago, intending to change mine at one stage, which I thought would be easy too, so could be school day for me too !

 

[karl2000]

Hmm if you cant get the bulb to light when you put the wires directly on the terminals, there must be a problem with the wires/circuit?

What happens when you turn your lights on and then check each wire with multimeter? If you put your meter on dc voltage, the -ve lead on battery ground, and the +ve on each wire, what do you get?

 

[karl2000]

PS my understanding of those H4 plugs is that they can be negatively or positively switched, just depending on how the three wires are used.

Ie for positvely switched, youd have one ground and two 12v wires - one for each light filament

For negatively switched (ie ours) youd have one 12v wire and two grounds. Note the grounds will only be grounded when rhe switch is on

 

[karl2000]

I have tested the loom wires independently with my test light and got battery voltage the same on all 3 wires .

So you've got three 12 V wires?

 

[karl2000]

When you're testing the wires on the passenger side you're probably putting the high beam switch wire to ground which enables the high beam on the drivers side

 

[tony rodaway]

Tony, for what it's worth Toyota lights are negative switched, maybe the new H4 plug with attatched wires is wired for positive switched so the wires are in the wrong position ?
Karl would be in more of a position to verify, maybe if you showed/explained the position of each of of those colours in the new plug ?
Oddly enough, I bought some of those, ages ago, intending to change mine at one stage, which I thought would be easy too, so could be school day for me too !

That explains why when I touched one of the wires with my probe light the other headlight turned to hi beam.

 

[tony rodaway]

Tony, for what it's worth Toyota lights are negative switched, maybe the new H4 plug with attatched wires is wired for positive switched so the wires are in the wrong position ?
Karl would be in more of a position to verify, maybe if you showed/explained the position of each of of those colours in the new plug ?
Oddly enough, I bought some of those, ages ago, intending to change mine at one stage, which I thought would be easy too, so could be school day for me too !

I connected my headlight prongs directly to the wire loom and in every combination possible and still no lights.
I did probe the loom wires with my tester and got 12v reading from all wires with lights on only.

 

[tony rodaway]

I will make a video clip and post to give u guys a better idea what I'm trying to achieve and my problems I have now hit.

 

[karl2000]

If youve got 12v on all three wires, sommat is wrong i think?

Back to basics for a circuit to work there needs to be a +ve and. -ve.

If all your wires are 12v there is no potential difference between them and no current will flow.

Maybe do the multimeter test if you can

 

[Gr8Yota]

So if I understand correctly there are two things going on here? 1) you swapped out the old H4 connectors for new ones. 2) you added in a lightbar to come on with hibeam.

1) If you simply cut and shut there should be no issues and doesn’t matter on pos or neg switching you’re just joining wires back up like fo like. Check your joins. Did you solder or use connectors?

2) to connect the lightbar use a feed off the hibeam wire at the connector to the light bar relay switch terminal (terminal number 86) So the hi-beam acts as the trigger to switch the lightbar relay.

 

[karl2000]

Agree just changing the plug doesnt make a difference from a pos/neg switching point of view, but then if it doesnt work, then it makes a big difference for troubleshooting as you obviously need to know what to expect on the wires

 

[Towpack]

This is the International standard for H4 bulbs, as used on the (positively switched) 80 series. Can't see why a 120 should be any different. Is the 120 Canbus? If you have neg switching the polarity will simply be reversed but the bulb connections for L/H will be the same.

 

[tony rodaway]

So to clarify my problem when I had my relay connected I dropped my small spanner and it landed touching my light bar plug to my hi beam with my lights on.
That is when my passenger side headlight when out.
With my h4 light plug still in place to my harness I first checked my fuses.
I noticed small sparks on one of the fuses but still worked as they should.
I probed both sides on the 4 fuses and power both sides of the fuses.
Never got the chance to look and make a video clip tonight cos of work.
Does this sound like a bad ground or there is a relay for the headlights so will have to try that also.
If I have a bad ground how so I find it and fix it as can't see it just being a connected wire to the body anyway must have to follow the loom I'm assuming.

 

[karl2000]

You need to find out whats on each wire with the multimeter mate

 

[tony rodaway]

I'm off work tomorrow so will get the multimeter out and test my harness and hopefully what I find will put me in the right direction to fix my problem and have daylight again hopefully.

 

[karl2000]

Ill look out for your update, im sure it will be easily fixed

 

[karl2000]

Had a quick check of the wiring diagram.

The 120 headlights are definitely negative switched.

I would double check the fuses again before you start.

Use the multimeter to check if each of your 3 wires on the passenger side is either 12V or ground.

Do this with the plug disconnected from the bulb, but with the headlight(s!) and high beams switched on.

The wiring colours are a bit confusing. On the passenger side, you have two wires that are red and green, and one that is red and white.

The red and white wire should be a GROUND - but it will only be a ground when the headlight is turned on.

ONE of the red and green wires should be 12V, and the other ONE will be a ground - but this time only when the main beam is turned on.

The two ground wires are effectively shared between the two headlights, as they come off the same switch.

When you connected the passenger headlight and the main beam came on on the drivers side, you must have been putting the main beam negative wire to GROUND. This makes me suspect that the two red and green wires you've got on the plug are switched around; so when you put the plug onto the bulb, the bulb made a circuit between two grounds, thus turning on the drivers headlight. This might be the first thing to check - just switch those wires.

You said earlier that you were getting 12V on all three of those wires. Make sure the connector is disconnected from the bulb when you check, and use a multimeter rather than a test light if you can. If you still get 12 V on all three wires, we've got a different problem.

Good luck!