Headlight Bulbs

[Morr]

......I've got mine wired like this
30 = +ve from battery (via fuse)
85 = Earth
86 = Feed from existing wiring loom
87 = Feed to bulb

No real difference, your wiring to terminals 30 & 87 are opposite to mine. Technically yours is 'more' correct as #30 is usually considered live in auto wiring terminology, however they are both effectivly the same. If you look at the small diagram of the internals of the relay, you will see that they are both on the same circuit with a switch to connect/disconnect them operated by the coil attached to terminals 85 & 86.
Therefore the important bit is that existing feed terminates thru 85 & 86 whilst new feed goes thru 30 & 87, once these pairings are adhered to it should work regardless of which wire goes to which terminal withinin the respective pairings. Hope that all made sense.

[Morr]

I have a problem with this.....
....

Andy, hang on till I have a think about this, when I drew the initial diagram I did not know the surf used a negitive switching system, I drew it from memory of every other car I've had, none of which used negative switching!
I'll get back to you.

[AndyLala]

Morr,


thanks for that.
A good autoelectrician friend of mine came out with this cracker the other day.

Positive switch, 30 live... (as you mention)
Negative switch, rotate the relay 180 degrees.
As long as the coil gets energised by the switch...

I have found a wiring diagram for the exterior lights... and that has given me a clue as to finding the common terminal at the bulb socket. I will investigate that during my lunch break. Then I will just use the relay's as per your diagram.

AndyL

[Morr]

Ok, been looking and thinkin 'bout this. I reckon the Surf will need the earth (shown in my diag as earth on terminal 85) changed changed to a new fused live feed, this will only need a low fuse rating (say 1 or 2 amps) at it will only be used to trigger the relay.
I've shown the diagram to an auto-elec and he concurs.

I was looking on the net for a pinout for the h4 bulb but did not find one, I happened upon the following information regarding using such a relay system on a negative switched system.

SPECIAL CONSIDERATIONS FOR GROUND-SWITCHED SYSTEMS

Many Japanese vehicles, as well as a few others, use a "ground-switched" headlamp circuit. In these circuits, the headlamp and beam selector switch break or complete the ground side of the headlamp circuit, rather than the feed side. On these systems, it's imperative to use both negative and positive existing headlamp wires to trigger the relays. It is tempting to run the existing headlamp feed wire to relay terminal 86 (trigger feed) and simply find a convenient ground for relay terminal 85 (trigger ground). However, this will not work with ground-switched systems. Run the vehicle's existing feed wire to terminal 86, and run the vehicle's existing ground wire to terminal85.

Now, what are we going to do now that we've used-up our one and only ground wire on the 85 terminal of the low beam relay, but we still have to install the high beam relay? Go to the other side of the car and you have another ground wire! Remember, the relay trigger circuits can be as long as you like, because they take insignificant power. So, you can extend the vehicle's existing headlamp wires to your relay mounting location. It is fine to use this method regardless of whether you have a ground-switched system or not, so go ahead and use it if you're not sure.

Now in all honesty this portion of the article only left me more confused, it appears more complex as I believe it intends you should intercept the live currently supplying the sytem and divert it to the relay, thus involving much more alteration to the original wiring loom than my suggested method.
You can find the full text of this, and some other usefull info at this site http://www.danielsternlighting.com/t...ys/relays.html



I would try switching the earth to a live as I have detailed above.

Let us know how you get on.

[AndyLala]

Ok,

a little more on this.

The common connector on the H4 bulb (at least on my vehicle) is the right hand pin.

Hold the bulb pointing at you, with the connector pointing away from you, with the connectors left, top and right. The right side pin is the common pin.

Something else is happening with the switched earth though.

The headlight is holding positive on the right pin. The headlight switch switches in earth to either the upper pin, or the left pin for main or full beam.

If we measure this, ie. between the headlamp socket and the battery, or the headlamp socket and a good earth, we get about a 4 - 6 volt drop... (Jotto's and Mine...)

So we do need an wiring upgrade.

So we replace the headlight with the coil of the relay. When each circuit activates, it energises the coil in the relay and switches in the other two connectors. You could switch in positive or negative to the bulb, the bulb doesn't care what it gets as long as there is a voltage across the element.

I have chosen to switch positive to the bulb. So 85 and 86 are the existing wiring. 30 and 87 the new upgraded feed to the bulb. Common on the bulb is now earth - direct to battery. (Type B Relay...)



85 and 86 get a potential difference (headlight main beam switched on), coil energises. Relay engages positive feed to the bulb, bulb should illuminate.

But... it doesn't.

Questions,
1) does the bulb take an earth from its mount (don't think so).
2) does an H4 bulb only do switched ground (nope, doesn't in a Ford Escort)
3) is there not enough of a difference in the headlight circuit to engage the relay... (Hmmm. it can illuminate the bulb...)
4) could there be an earth loop between the existing loom and the new loom (possibly)
5) could the relay's be duff (possibly)

Anyone else actually done this, that would like to share their experience?
At the moment I feel like setting fire to the whole thing...

yours desparately, andyL

[rusty]

No real difference, your wiring to terminals 30 & 87 are opposite to mine. Technically yours is 'more' correct as #30 is usually considered live in auto wiring terminology, however they are both effectivly the same. If you look at the small diagram of the internals of the relay, you will see that they are both on the same circuit with a switch to connect/disconnect them operated by the coil attached to terminals 85 & 86.
Therefore the important bit is that existing feed terminates thru 85 & 86 whilst new feed goes thru 30 & 87, once these pairings are adhered to it should work regardless of which wire goes to which terminal withinin the respective pairings. Hope that all made sense.

Well blow me down I didn't know that.
Cheers

[Morr]

.........
Questions,
1) does the bulb take an earth from its mount (don't think so).
2) does an H4 bulb only do switched ground (nope, doesn't in a Ford Escort)
3) is there not enough of a difference in the headlight circuit to engage the relay... (Hmmm. it can illuminate the bulb...)
4) could there be an earth loop between the existing loom and the new loom (possibly)
5) could the relay's be duff (possibly)

Anyone else actually done this, that would like to share their experience?
At the moment I feel like setting fire to the whole thing...

yours desparately, andyL

Andy, sorry but haven't much time at the mo to think further on this, in answer to your first question, correct, it does not earth thru the mount.
I'll try think on this over the weekend and get back to you again.

[AndyLala]

Found something that made me think...

Positive switch is fine... Relays are meant to wire in a particular direction...

Negative switch, works backwards.

Quote from http://www.rowand.net/Shop/Tech/Wiri...ightRelays.htm

"Some import cars, particularly Toyota's from the early to mid 1980's use a really weird "negative switched" system that runs power direct to the headlights and puts the switch after the headlights in the wiring diagram. You can do the same relay trick in those systems, but several key wires are inverted, and you need to be really careful about what you do because most people have trouble thinking about the system working "backwards"."


I need to understand what he means by several key wires.

This may trip some thought processes on your part Morr...
I'll continue looking for related stuff.

AndyL

[AndyLala]

It does get bad when you answer your own posts...

I had to get my mind off it, and think about something else to sort my head out...

Then it came to me... keep it simple, stupid.

RTFM...! Eat your own dogfood....!



when you order something, make sure that it is what you ordered.

With relays that is very important. Type b, as above, is as per the Bosch layout of 5 pin relays without the 87a pin in the middle, parallel to 87...

try not to wire up a relay as if it is a type b when it is infact a type a, you are very likely to start at fire...! Been then, nearly did that yesterday!

86 and 85 are the coil. a potential difference of more than about 6volts will energise the coil and activate the relay, switching the supply plugged to 30 through 87...

Remember OEM loom shows a voltage drop of anything between 2 to 3 volts, I have seen a drop of 6 volts... on some... at the headlamp socket. Get as much current there as you can, and your bulbs will actually light the way. A 2 to 3 volt drop can mean approximately 30 - 40% drop in light output. (See Roger Brown's in depth desciption of the issue. http://www.4crawler.com/4x4/CheapTri...adlights.shtml)


So anyone want a headlamp loom? that will keep the main beam on, when you switch in the full beam... you will notice a difference even with the normal spec bulbs... put uprated in there, and it'll be daylight... almost. No pictures, yet, it wouldn't do it justice.

Send me a pm, or email.

AndyL

[waveydavey]

OK people, for all the numbty's out here give us a clue as to what wire we ask for in Halfords ect!!!
Thanks

[AndyLala]

Don't ask Halfrauds, ask me. I'll even make it up for you... and you can feel good about it, 'cos it'll be benefitting the forum...


andyL

[Morr]

Don't ask Halfrauds, as me. I'll even make it up for you... and you can feel good about it, 'cos it'll be benefitting the forum...


andyL

Glad you've got it sorted Andy.
Was I right did you have to switch the earth in my diagram for a live on terminal 85?
either way at least you've discovered the problem, we can all stop bending our brains round the problem.

[Verbal]

Andy - you have an E-mail.

Also how easy is it to link spots into this loom so they come on with the full beam as well. As i have a set of spots that are on a seperate switch, that I want on the normal full beam.

[AndyLala]

Fairly straight forward. Another pair of relays, some more wire, and as long as they are happy being negative switched.... you are good to go.

***********
Actually, dead easy. Headlights are now switched positive in the mark2 loom, so we just tap into the full beam and job done, we can switch those positive too.
***********


andyL

PS. Verbal, I will respond to your email when I get home. No access to that account from work...

[Medieval Dave]

Where did you mount those relays? all together or local to the headlamp to pick up the origional looming there?