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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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LED H4 lights only work on full beamViews : 1470 Replies : 22Users Viewing This Thread : |
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Jan 14th, 2021, 16:19 | #1 |
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LED H4 lights only work on full beam
I recently bought a set of Nighteye H4 led headlights from eBay as I know a few people with them and they worked well. I installed them in my car but for some reason they were stuck on full beam even without the full beam turned on. I have my switch in the right position but if I put it on sidelights then the dip beam comes on.
Upon closer inspection there are 3 leds on the bulb, 1 should light up for dipped and all 3 for full beam, when in the car 2 light up for dipped and 3 for full and if I measure the voltage on the car terminal I get 12 volts on dip beam to ground and still on dipped bean I got 1.6v on full beam to ground. I retested this today and got 0.05v with 1 original bulb connected the other side. It seems like the issue is that some current is passing down the full beam wire and causing the Bulbs to illuminate when they shouldn't presumably cut LEDs require a lower voltage? I'm pretty useless with electronics so this is where my limit is, does anyone have any advice on what to check next or what could be causing this voltage on the high beam side when not in use and any ways to rectify the issue? Has anyone else used LEDs and had this issue? Thanks in advance!! Last edited by ANDTWENTY; Jan 14th, 2021 at 17:42. |
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Jan 14th, 2021, 17:20 | #2 | |
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Also i'm not following your description of the "shoals" of LEDs lighting up, dipped beam should bring the two rows on that are next to the shields, full beam should bring on the other set. Also don't forget you have dim-dip on your car so with the lights switched off, the sidelights and dim-dip come on with igntion. This stays the same when you switch to sidelights + ignition (but only gives sidelights with no ignition) and dipped beam should come on bright when you switch to headlamps. Full beam should only come on when you intend it to, either by flashing or by pulling the stalk far enough to switch from dipped to full beam. It sounds like the bulbs you've bought are faulty if i've followed your description correctly but there might be a bad earth somewhere complicating things. Did dim-dip work on the normal H4 bulbs?
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Jan 14th, 2021, 17:50 | #3 |
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Dipped beams
Probabaly the reduced voltage of the dipped beam is already enough for the LED headlights to give a full light. Unlike a normal bulb or halogen LED cannot be dimmed by reducing the voltage.
If this is the case then disconnect the resistor. |
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Jan 14th, 2021, 17:51 | #4 | |
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Soals was meant to be should, I have now amended this. I tested the bulb with wire from a battery and when 12v is applied to the dipped pin it lights 1 led and when its connected to the full beam it lights all 3 but when its fitted to the car it lights up 1 with sidelights 2 on dipped and 3 on full beam. does this mean then that its correct? Im not sure I understand the dim-dip thing. with my original bulbs sidelights were just sidelights headlights were dipped beam and full beam were full beam with another bulb to the side above the fogs, not sure what this is called. There are only 2 filaments on the original bulb, 1 for dipped 1 for full beam. |
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Jan 14th, 2021, 18:06 | #5 | |
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Dim-dip is meant to bring the dipped beam on dimly when only sidelights are selected - with a Volvo that has DRLs, the dim-dip comes on anyway but the output even with LED bulbs is less intense. If the three LEDs you describe are arranged in a triangular formation around the "bulb", they almost certainly won't pass the MoT because of beam pattern. Sounds like you have driving lights above the fog lights built into your headlamps, these should come on with full beam only. This is dipped beam : ......... and full beam : If you're not getting a distinct difference like that then there's something wrong somewhere. To give you an idea, those speed limit signs are about 1/4 mile up the hill from me. Also if you drive close to a wall on dipped beam, you should get a fairly crisp pattern, along the lines of the bottom pattern shown here : There shouldn't be any light above the cut-off line except the lick-up on the left and then only in a defined area as shown.
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Jan 14th, 2021, 18:10 | #6 | |
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That's not the problem though as i understand it, it seems the bulbs have been wired up wrongly for a start and if i've understood the description of the actual bulbs, won't ever give the correct beam-pattern to pass the MoT - i have several pairs of cheap ebay H4 LED bulbs that have no hope of passing the MoT but will serve duty in other applications.
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Jan 14th, 2021, 18:22 | #7 |
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Yea sounds like its driving lights then, its a small bulb, H3 I believe, above the fogs that only comes on with full beam. I'll go pop the bulbs in and pull up to a wall and see what I get pattern wise. |
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Jan 14th, 2021, 18:52 | #8 |
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Just been reading this posting and I have some bad news for you . Your car was designed to use halogen bulbs , new MOT regulations entering service shortly will prohibit the fitting of HID or LED light sources into such headlights
https://www.gov.uk/guidance/mot-insp...ical-equipment 4.1.4. Compliance with requirements Existing halogen headlamp units should not be converted to be used with high intensity discharge (HID) or light emitting diode (LED) bulbs. If such a conversion has been done, you must fail the headlamp. And that is direct from our test manual . The only " legal " method of using HID or LED in an old vehicle is to retro fit projector units , having removed the reflectors or find projector headlights for your car
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Jan 14th, 2021, 19:42 | #9 | |
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Jan 14th, 2021, 19:44 | #10 | |
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I've heard rumours of "approved" LED bulbs being allowed to be retrofitted becoming law soon as well so i'm going to sit it out.
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