Should H4 headlights have relays wired in?
- Thread starter Webley1991
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Webley1991
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I had a look at the wiring a few days back. I can see the dip and main beam cables routed along the top of the driver's side wing.
I was thinking I could get hold of a relay with two sets of live in/out terminals and two switch teminals. I am not sure what the correct terms for the pins are.
From what I understand, I could simply cut the wires, crimp on some spade connectors for the relay and run a live from the starter motor to power the lights. Am I right that the relay also has earth pins for the switching connection?
Can anyone with better electrical knowledge recommend a particular relay part number? I am thinking this could be a cheaper and simpler way to do it than replacing the whole wiring looms for the lighting.
I was thinking I could get hold of a relay with two sets of live in/out terminals and two switch teminals. I am not sure what the correct terms for the pins are.
From what I understand, I could simply cut the wires, crimp on some spade connectors for the relay and run a live from the starter motor to power the lights. Am I right that the relay also has earth pins for the switching connection?
Can anyone with better electrical knowledge recommend a particular relay part number? I am thinking this could be a cheaper and simpler way to do it than replacing the whole wiring looms for the lighting.
Basically any Bosch type 5 pin relay will do the job. 12v bosch relay would be your search term or request at the parts counter
Or you can by inexpensive kits off ebay or amazon, either as a relay harness or as a generic headlight wiring harness that may or may not fit properly
https://stickerdeals.net/wiring-diagram/bosch-relay-wiring-diagram/
They will all be labeled and by terminal the wiring goes as such.
86 is Earth
87 is Load ( big wire to load)
30 is Feed (big wire from battery +, fused as necessary)
85 is trigger (little wire from switch, or in this case the feeds from existing high and low beam wiring respectively)
Or you can by inexpensive kits off ebay or amazon, either as a relay harness or as a generic headlight wiring harness that may or may not fit properly
https://stickerdeals.net/wiring-diagram/bosch-relay-wiring-diagram/
They will all be labeled and by terminal the wiring goes as such.
86 is Earth
87 is Load ( big wire to load)
30 is Feed (big wire from battery +, fused as necessary)
85 is trigger (little wire from switch, or in this case the feeds from existing high and low beam wiring respectively)
ExMil109
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+1 on Erik's post.
If you prefer to use a double relay, you could use something like this, which is basically just two relays in a single package:
https://www.autoelectricsupplies.co.uk/product/728/category/36
Some kind of inline or strip fuse in the feed into the relays would be a good precaution.
If you prefer to use a double relay, you could use something like this, which is basically just two relays in a single package:
https://www.autoelectricsupplies.co.uk/product/728/category/36
Some kind of inline or strip fuse in the feed into the relays would be a good precaution.
Webley1991
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Thanks for the replies. One problem I can see with the double relay is that if one side fails, the whole unit would need to be replaced.
Could I feed the live for both the dip and main beam through the same wire/fuse and split it just before the relay? Anything to keep the number of wires in the engine bay to a minimum.
Could I feed the live for both the dip and main beam through the same wire/fuse and split it just before the relay? Anything to keep the number of wires in the engine bay to a minimum.
The feed for terminal 30 could certainly just be a single wire that is split/Y'd at the relays and used to feed them.
If I were doing this without any other wiring changes I think I would get relays with waterproof and fused housing and mount them on the bulkhead near the existing 3 way bullet connector. Then I'd yank the existing headlight harness beyond that 3 way and cut off the bulleted ends with enough length to attach to the 85 terminal or wire that runs to the 85 if you use a harness. This way your wiring matches the proper color codes at least to the relays. Which for me would make trouble shooting things a bit easier 5 years down the road when I am trying to remember what the heck I did.
Then I'd likely match the tracer color for for my 87 feeds out to their respective bulbs since I have trouble finding primary wire with tracers but can get whatever single color I want within reason.
mystery
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Can't see why you would go to the trouble of fitting relay/relays in the engine compartment and the problems of water ingress when you have excess to the fuse box and lighting cables behind the steering column
you also can buy relay bases that clip together that can be fixed to the dash rear and any faulty relay can easily changed or https://polevolt.co.uk/acatalog/40A...bracket.-Double-NO.-Form-B-2698R.html#SID=136
you also can buy relay bases that clip together that can be fixed to the dash rear and any faulty relay can easily changed or https://polevolt.co.uk/acatalog/40A...bracket.-Double-NO.-Form-B-2698R.html#SID=136
mystery
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snip...
I'd do it that way for a few reasons.
Personal rig is a 2a so I have none of this fusebox inside the cab nonsense.
I'd rather pop my head into the engine bay than fiddle behind/under the dash.
I want to up the wire gauge to the headlamps to take maximal advantage of fitting the relays.
I think I actually have less water ingress in the engine bay than behind the dash judging from the standing water on my rubber floor mats after every rain.
Mine are fitted on the slam panel been there a good few years water has not been an issue even though I do some off roading.
3rd one is for my electric fan. as my battery is under passenger seat my fuses are there too.
Under seat set up shown is earlier version have changed it a bit as put new seat box in and bigger battery
3rd one is for my electric fan. as my battery is under passenger seat my fuses are there too.
Under seat set up shown is earlier version have changed it a bit as put new seat box in and bigger battery
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mystery
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THE ORIGINAL THREAD WAS FOR A SERIES 3 AND AS YOU SAID YOUR'S IS A SERIES 2A ?
less fuses and the use of a junction box to connect the floor mounted foot headlight dip switch unless it's been altered ,you may also have the luxury of Magna Tex indicator
column switch ,if you are going to fit the relays the wiring is basically similar but in your case if you are going to this trouble it would pay to up-grade the fuse box and this would give you
fuse protection say for your inspection socket ,wiper motor,,brake lights ,side and tail lights etc some info on circuit diagram etchttps://www.landyzone.co.uk/land-rover/wiring-harness-help.349122/#post-4633031
less fuses and the use of a junction box to connect the floor mounted foot headlight dip switch unless it's been altered ,you may also have the luxury of Magna Tex indicator
column switch ,if you are going to fit the relays the wiring is basically similar but in your case if you are going to this trouble it would pay to up-grade the fuse box and this would give you
fuse protection say for your inspection socket ,wiper motor,,brake lights ,side and tail lights etc some info on circuit diagram etchttps://www.landyzone.co.uk/land-rover/wiring-harness-help.349122/#post-4633031
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