Relaying Lights-ZX TD

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
Guru Meditation
Posts: 259
Joined: 18 Dec 2002, 02:30
Location:
My Cars:
Contact:

Relaying Lights-ZX TD

Post by Guru Meditation »

Right, I've just fitted some Osram Silver Star to the dipped beams of my ZX and I am quite impressed-they put noticeably more light onto the road. But I want more! I am now on a bit of a lighting bent and with this alarm fitting and stuff I'm right into this electrics stuff and want to relay both my high and low beams. Anyone got any pointers?
I think the basic premise is to get two relays (16A automotive use ones £1.49 from Maplin-are these suitable?) and connect a nice 12V feed to the switched side of the relay direct from the battery with chunky wire and an inline fuse(what rating?)(what gauge wire is suggested?) the other switched side of the relay to the positive side of the light bulb, leave the existing earth connector of the light bulbs as they are and then connect the existing positive input to the light bulb to the control coil of the relay and create a good earth for the relay coil, thus controlling the relay with the existing wiring?
When I'm done with the relaying I want to put 100W in the main beam.
User avatar
AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
Location: Denmark
My Cars:
x 1

Post by AndersDK »

Hi gm -
I like the idea you have using relays - one of the most sure ways to feed adequate power to the bulbs - and the most wellknown DIY "repair" on elderly cars to regain lights efficiency.
The Maplin 16Amp relay is not suitable - you need a standard automobile relay rated at least 25Amp - better to use 40Amp.
The reason is that the bulb's filaments when cold have a very low resistance - making for very high inrush currents at switch-on.
Standard automobile relays for horns, lightings etc. are cheap & easy to get everywhere - even a breakers where you simply rip a handfull from any car's junction box - would be approx £1-£2 ea.
The installation is very straightforward :
Simply find the wires feeding the bulb filaments - then cut and feed the bulb filaments from the relay contact - other side of contact feeded directly from battery.
The original bulb filament feed from lights switch is simply connected to one side of relay's coil - the other side is grounded.
Use adequate gauge wire for the battery feed to relay contacts - and fit an in-line fuse in battery feedwire to protect your wiring against fire in case of shortcircuits (incidents) - fuse rated at least 30Amp.
Note that any dim/dip circuitry may need some "extra brains" to the modifications - just a challenge [:)]
Guru Meditation
Posts: 259
Joined: 18 Dec 2002, 02:30
Location:
My Cars:
Contact:

Post by Guru Meditation »

I hadn't thought about the dim-dip system. That'll be an entertaining puzzle. Maybe the dim-dip circuit will have to be rejoined to the bulb filament after the new relay, so dim-dip will still work?
I was looking at the 40A relays but they are more expensive! Might just get down to the scrapyard like you suggest.
BonceChops
Posts: 449
Joined: 28 Sep 2003, 11:08
Location: North West UK
My Cars:

Post by BonceChops »

When I did mine I was not bothered about the dim dip system. I would use 2.5mm cable. If you want to prove your old wiring is poor test it with a volt meter. With the lights on connect one probe of the voltmeter to the positive of the bulb and the other probe to the positive of the battery. The volt reading you get is the volt drop of your wiring. If you then put a tempory 2.5mm wire from the bulb positive to the battery positive and test with the meter again you will measure the volt drop with the new cable and see the improvement. Test the lamp furthest from the battery. I was losing 2 volts on my wiring with 100w bulbs. When I put the tempory wire on they looked whiter.
You could also measure volt drop between negative of bulb and negative of the battery to prove you have a good earth ( in car terms :) ) connection. You may need to improve that wiring as well.
Neil
Guru Meditation
Posts: 259
Joined: 18 Dec 2002, 02:30
Location:
My Cars:
Contact:

Post by Guru Meditation »

Right, I've got my mitts on 4 relays from the scrapper (dunno if four are needed but a couple may be faulty, or all of them). They look a bit weedy but hopefully they will be ok. They are small brown ones marked 12v 25A/20A. 40A would be better I suppose but if I can get away with these I will, they were all I could find as it was wet, muddy and I took no tools with me. I need some wire, inline fuse holder, 30A fuses. I've got my crimp kit with scotchlock wire connectors etc.
davey
Posts: 68
Joined: 05 Dec 2003, 01:56
Location: United Kingdom
My Cars:

Post by davey »

Guru,
be wary of simply grounding the 'ground' of the original feed wiring. This 'ground' is not always a true ground. Always safer to connect both the original +ve & 'ground' to the coil side of the relay rather than take the 'ground' to chassis. On the contact side its ok to take to chassis.
I did as suggested once on a subara justy - its soooo reliable - simply put my grounds to chassis as a result the aux lights came on with engine running and went off on main beam!!
ZXturbo_Aura
Posts: 148
Joined: 10 Oct 2003, 02:56
Location: United Kingdom
My Cars:

Post by ZXturbo_Aura »

the dim/dip shouldnt be a problem for the ZX uses two 55w bulbs in each headlight?? i.e. one for dipped, one for high beam, you would have to use one relay for dipped and one of high, as long as you take the switching feed for the relay from the suplly for dipped and high seperatly your dim/dip will still function fine
Dan
ps. doing mine on sat! 90w dipped and 110w high :P :)
Guru Meditation
Posts: 259
Joined: 18 Dec 2002, 02:30
Location:
My Cars:
Contact:

Post by Guru Meditation »

I thought the dim-dip system is where by when only sidelights are switched on a relay and a resistor also energizes the dipped beams (the outer bulbs on the ZX) to approximately 1/6 normal brightness. When you put a relay to control the dipped beams and control the relay with the original wiring you will lose the dim-dip unless you do something about it. Another thing, I take it the dim-dip system will not put enough voltage through the wires that you are now controlling the relay for the dipped beam with to energize the relay will it? ie leading to the full dipped beams coming on when you switch sidelights only on, if you get what I'm saying? Or am I totally off the mark?
ZXturbo_Aura
Posts: 148
Joined: 10 Oct 2003, 02:56
Location: United Kingdom
My Cars:

Post by ZXturbo_Aura »

sorry, i wasnt aware of that! oops! ill look it up in the big BOL later on tonight, didnt know about the side lights etc, presumed ther was a smaller wattage bulb in the headlight unit, silly me! lol!
Dan
ps ill work summat out! lol.
Dave Burns
Posts: 1915
Joined: 14 May 2001, 05:30
Location: United Kingdom
My Cars:
x 2

Post by Dave Burns »

Don't use scotchlocks for the power side, only for the switching side, avoid potential resistive joints like crimps too by not crimping them but soldering them up solid on the power side, use mechanical joints where you have to, physical (solder) ones where you can, if you want to maximise your efforts.
Dave
BonceChops
Posts: 449
Joined: 28 Sep 2003, 11:08
Location: North West UK
My Cars:

Post by BonceChops »

Crimps are ok when you use a proper ratchet type crimping tool. The rubbish plier type do cause bad joints and belong in the bin. I agree that soldering is best, but can be difficult for some people to do well. Especially with big cables onto relay blade terminals.
The multimeter test is worth doing before starting - just to prove you have a volt drop problem.
Neil.
Guru Meditation
Posts: 259
Joined: 18 Dec 2002, 02:30
Location:
My Cars:
Contact:

Post by Guru Meditation »

Doh my crimping tool is the plier type-looks like I'll be getting the soldering iron out.
I haven't actually tested with my multimeter in all honesty-part of the reason I'm doing this is because I am thinking of putting higher wattage bulbs in main beam (not strictly legal I know) and am concerned about overloading the switch, might do the test before I start though just to see what difference it makes before and after.
Post Reply