Headlight relay upgrade

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scotttie
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Headlight relay upgrade

Post by scotttie »

I know this topic has been done to death, so I have tried to read as many old posts as I could find on here and the wiki but I still have a couple of questions.

A few places are now selling a headlight relay upgrade loom that goes from the battery via relays to the headlights, triggered by the old headlight wiring at one of the headlight connections. To me this doesn't seem like the nicest solution as you are adding a lot of wiring for one job, bypassing the fusebox, eliminating dim dip, and placing relays on the exterior of the van (behind the grill). Though it does seem like the easiest way of doing it which is always tempting!

From the useful illustration on wiki (https://wiki.club8090.co.uk/index.php/F ... itions.jpg) I like the look of option A which would mean the power going from the relay to the headlights would still run through the original fuses. My understanding is 56a and 56b will be the triggers for the relay which will go to an earth after the relay. Main power to the relay will come from one of the spare P terminals on the fusebox and from the relay that will then feed into the fuses 56a and 56b originally fed into. If I am right in thinking this is the best option, I have a few of questions I'm hoping someone might be able to answer:

1. Is the original wiring from the battery to fuse box, and from fuse box to headlights adequate to deal with the extra voltage from the relays? (assuming all connections are good)

2. The relay trigger wires (56a and 56b) now do not have a fuse in the circuit. Should an inline fuse be added before connecting to the relay?

3. What relays have people used for this job?

4. Whilst doing this I am also going to be swapping my single round headlights for the twin SA set up. I wont have the wiring in place for the inner lamps, so I am assuming it is OK to just piggy back off the full beam wire going into the outer lamp?

What I have noticed from reading up on this topic is there isn't an obvious how to guide. So I'd be happy to take some pics and document the process when I do it if it will be of use to others?

Thanks,
Scott


 
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Re: Headlight relay upgrade

Post by Mocki »

I took a feed direct from the main battery to the relays , so the original wiring only triggered the relay , which is the whole point of the job .....

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Re: Headlight relay upgrade

Post by crazyhorse »

scotttie wrote: 10 Mar 2021, 12:58

What I have noticed from reading up on this topic is there isn't an obvious how to guide. So I'd be happy to take some pics and document the process when I do it if it will be of use to others?

Thanks,
Scott


 


Defo interested in this
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scotttie
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Re: Headlight relay upgrade

Post by scotttie »

Mocki wrote: 10 Mar 2021, 18:50 I took a feed direct from the main battery to the relays , so the original wiring only triggered the relay , which is the whole point of the job .....


Thanks Mocki, I came across that diagram when searching through some of the existing threads on the forum. What I am suggesting is the same as what you've described above, but instead of running a separate feed from the battery to the relays, you can take a live feed from the fuse box. Maybe my understanding/explanation isn't very clear. I have since found a really useful thread in the tech archive (viewtopic.php?f=39&t=96326) which as a detailed explanation by syncroandy:

"I used two 'number 53' 40A relays (one for main, one for high), together with mounting plates (161 937 501 B). The mounting plates use std. 1/4" barbed uninsulated brass crimp terminals. My van is base-spec, so a number of the single 1/4" terminals ('P') normally used for high-current accessories (aux. heaters and the like) are still available. These are on the back of the relay plate and commoned together onto the heavy terminal 30 bus-bar inside the plate, which has a 6mm connection to the battery, so should be good for a few amps !

I cut into the main and high beam wires (2.5mm yellow and white) coming from stalks about 4" from the relay plate, and soldered an additional 6" onto the end coming from the stalks, the join was insulated with heat-shrink tubing. This was connected to terminal 85 on the relays, and terminal 86 was connected to earth via a 1.5mm brown wire to the earth crown. (I had previously added another crown so had several spare connections.) I made a separate connection using about 6" of 2.5mm red wire from one of the P terminals to terminal 30 on each of the relays. The yellow and white wires going to the relay plate were connected to terminal 87 on each relay. As can be seen from the diagram, they then split into two inside the relay plate and each lamp has its own 10A fuse (no. 9,10,21,22).

This upgrade is intended only for standard spec (ie. legal) headlights, if high-power lamps, or a battery of spot-lamps have been fitted, I think a separate connections to the battery and to the lamps should be used. Also if the van has aux. heaters, aircon, headlight washers etc. then there may be no free 'P' terminals, and so a separate battery connection used.

All I've done is follow the scheme as I understand it used by many others, including some commercial kits. It's a long time since I did my Electronics HND, so it's entirely possible I got it wrong, but it works for me anyway !"


I think this answers most of my questions.
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Re: Headlight relay upgrade

Post by boatbuilder »

I did this upgrade a few months ago - I bought a cheap relay loom off ebay with ceramic h4 plugs on it. Just search for "H4 relay harness". Loads of them available for around a tenner.  The two relays that came with mine have a transparent plastic casing.
I ran a new wire with 40A fuse from the battery in the engine bay, underneath the van in some corrugated conduit and up through the rubber grommet that the heater matrix pipes go through.  
I use that wire for the power steering and also the headlights - each with their own inline fuse.  I didn't bother to fit an actual fuse box, just soldered the wires in a Y.
It was as easy as running the wire out through the front panel and connecting it to the relay loom.
Also fitted an earth point beside each headlight that also connects to the loom.
I put the relays in an electrical box beside the front right headlight - there is a handy hole there to shove them into.  Fitted nightbreaker bulbs too.
The original h4 plugs were left in place - the right side one is plugged into the loom to trigger the relays.  The left side one was just tied up out of the way.
Brilliant upgrade and I'm happy with the ebay loom.  :ok
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Re: Headlight relay upgrade

Post by AngeloEvs »

Mine is wired the same as Mocki describes but the relays are mounted behind the cosmetic black plastic panel under the centre of the dash. You don't have to mount them behind the grille.
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Re: Headlight relay upgrade

Post by bigherb »

I always do option A, Noting wrong with the actual wiring to the headlamps as long as the connections are clean. I do fit a supplementary earth behind the head lamps to help shorten the earth return path. Just use good quality relays.
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scotttie
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Re: Headlight relay upgrade

Post by scotttie »

I've since decided to go with option B, mainly for two reasons. 1, post fusebox there are 4 wires going to headlamps (main and dipped for either side) which allows me to have a separate relay for either side in case a relay decides to fail. 2, the relay trigger circuit is still fused with the original fuses (with option A the trigger circuit isn't fused at all but I dont know if it needs to be - unless you add inline fuses). To fuse the power going to the headlights I've gone for Durite fused mini relays (https://www.12voltplanet.co.uk/standard ... -fuse.html), which I will put a 10amp fuse in to protect the original wiring. Going to get started on this job this weekend so will take some pics as I go.
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Re: Headlight relay upgrade

Post by scotttie »

Just finished wiring in the relays, and I thought I'd do a write up in case it's of use to others who are interested in doing it in the same way. 

Firstly I would just like to caveat this by saying I am no expert in electronics, and this is just the way I decided to do it after reading up on the subject and studying wiring diagrams. There are many ways to do this and I'm not saying this method the best or the only way it should be done! What I can say is it's definitely made my headlights a lot brighter! Also worth noting this is for a UK RHD 1988.

I went for option B from the diagram on wiki in the following steps:

1. Locate the 4 wires going from the back of the fusebox to the headlamps (yellow - left dipped, white - left main, yellow/black - right dipped, white/black - right main). These will be going from the bottom middle connector at the back of the fusebox into a loom that goes through the grommet to the front of the van. I cut these wires about 5cm from the fusebox leaving me enough room to solder some extra lengths on. Make sure you have definitely located the right wires as there are a couple of yellow and black wires going to the front of the van. They are subtly different, and if you're unsure, remove your headlights and look at the wires going into the bulb holder to compare against.

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The extra lengths I soldered on will be the triggers for my relay (relay terminal 85). I covered them in some heat shrink and tried to keep to the stock wire colours. The white and yellow wire I have used is same as original 1.5mm² 21amp.

2. The trigger circuit will need to go to earth from relay terminal 86, so next I made up some lengths of brown 1.5mm² 21amp. These will go from relay terminal 86 to spare earth crowns.

ImageImage

3. Power going to relay terminal 30, which will be the power going to the headlights, comes from the spare P male blades at the back of the fusebox. These P terminals are for high power items (aircon etc), luckily (or not so) my van is basic spec so I have quite a few spare. I made up some lengths of 2.0mm² 25amp wire with insulated male spade terminals so they don't accidently short on anything.

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4. Where the headlight wires were cut near the fusebox, take the sections going to the headlamps and add spade terminals with latches. The latches are needed to fit the terminals into the relay holders. These are the original wires taking power from the fusebox to the headlights, but instead the power will now come from the relay.

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5. Now all 4 connections are ready, the relays can be installed. As suggested by others I picked up some relay holders (161 937 501 B) that clip to the top of the fusebox. Each slot in the relay holder is numbered. 6 = trigger wire from fusebox (with extra length soldered on), 4 = Earth for trigger circuit going to earth crown, 2 = power from fusebox P terminal, 8 = original wire going to headlight

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6. Now the satisfying part, add male spade terminals with latch to the trigger wires, earths and power wires and slide them into the correct locations on the relay holders.

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7. Fit relays with 10amp fuses (same as original and protects original wiring)

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I was hoping dim dip was still going to be functionable with the relays, but the dim dip resistor joins the headlight circuit before the full beam stalk switch. The only way to retain dim dip is to put the relays before the switch which would defeat the point. Therefore the dim dip circuit needs to be disconnected, otherwise it will trigger the relays when the dash light switch is on position one and you'll get dipped beam instead of just side lights. I disconnected the dim dip circuit where it comes from the resistor back into the van there is a yellow single pin connector that a simply unplugged (it's behind the fusebox and the wire colour is yellow/black). This means light switch position 1 = side lights only, and position 2 = dipped beam.
 
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Robsey
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Re: Headlight relay upgrade

Post by Robsey »

That should certainly do the trick.

I have a slightly different twist on this.

I will be taking relay control feeds directly from the dip / high beam switch.
My van 'had' the old style fuse box, so the 2.5mm wires from the switch had female spade connectors already fitted at the fuse box end.

Working on the old (1983) dash loom.
I unclipped the 2.5mm white / black wire and the red / yellow wire from the old stalk switch socket.
And slid them out of the plastic tube on the stalk loom.
On the early van loom, the white / black wire that feeds the dip / high beam switch is linked directly to the main light switch... not to the fuse box.

(On the later van loom, it goes from the light switch, across the van to the fuse box and then back again, across to the dip / high beam stalk switch.)
Quite a lengthy run...

I then removed the white wire, and ( in my particular old van) yellow / black wire from the remainder of the dash loom.
--------------------------

Working on the later (1987) CE1 dash loom.

I unclipped the 2.5mm white / black wire and the red / yellow wire from the NEW stalk switch socket.

I then inserted these into the tubing and socket from the early stalk loom.

I then worked my way along the dash loom from the stalk end towards the fuse box end.
Separating out the white and yellow wires, and binding in the early white and yellow / black wires and stalk loom.

Approx. 8" (20cm) from the fuse box, there is a 'natural' junction where all the link wires diverge from the two main looms for the red and blue connectors.

At this point, both the early loom pair of wires, and the later loom pair were also tailed away from the main loom.
------------------------------------
As said, standard "53" relays will do the job.

Now using standard relay etiquette...

Relay 1 ( dipped beam circuit)
Term 86 - trigger = yellow / black from stalk switch.
Term 85 - to ground.
Term 30 - to the battery feed (P) or extra battery cable.
Term 87 - output to load - yellow wire to CE1 fusebox.

Relay 2 (high beam circuit)
Term 86 - trigger = dirty white from stalk switch.
Term 85 - to ground.
Term 30 - to the battery feed (P) or extra battery cable.
Term 87 - output to load - white wire to CE1 fusebox.

I will be putting a separate battery cable in for my power steering, so it would make sense to use this to power the head-lamps.
1983 Tin Top with a poorly DF and 4 speed DT box.
Soon to have a whizzy 1987 DJ.

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