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I have a pair of LED car headlights wired in parallel with a single power feed and a single earth.
When I test in the garage they both perform identically in terms of brightness etc.
When I fit them to the car the main (bigger) lamp is dimmer. This is for the side light, head light and main beam. The other side is exactly the same so I do not think it is a faulty lamp, it works fine in the garage after all. The picture below shows what I have done so far. The picture of the side lights when fitted to the car isn't great but believe me when I say that the smaller lamp was as bright as it was in the garage but the bigger one was a much dimmer, almost yellow light.
https://photos.app.goo.gl/SvsZVozYcZgm57aV6
Voltage checks were done at the point where the lamps connect to the power source so it cannot be the wiring between that point and the lamp unit. If I remove the smaller lamp and just test the bigger lamp is still dim.
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I suspect it must be insufficient Amps but not sure how to check this. I have this multi-meter but have only ever used it to check for 12V. Which probes in which holes and what setting on the dial please
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https://photos.app.goo.gl/EEqPF2q8Q8y3mJKBA
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Any suggestions welcome. I was so pleased when I connected up the headlights, main beam, indicators, side lights, additional indicators and fog lights with power in all the right places. After fitting them into the car and fitting the front wings, I was dispondent to see the sudden difference.
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Please help
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How much current should they be drawing?
Are they cheapy eBay jobs?
What car?
I'd be wiring then through a relay that took a direct feed from the battery (with appropriate fuse)
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Tbh if the voltage is right it sounds like they're drawing more current than can be supplied by the loom, which is a recipe for an electrical fire.
They are replacing Xenon headlights in a Porsche 997.1.
I suspect a lack of power too, which is why I asked how to use the multi meter to check.
I don't really want to cut into the standard Porsche wiring loom so want to be sure that is the issue before I plan my next course of action
Lights were from a UK based shop , not that means to much I guess
Iām no expert but could it something as simple as the lights requiring the engine to be running for full brightness? If the engine is not running there would be a danger of draining the battery.
Or some sort of dim/dip arrangement? My 35 year old Landrover has this
Engine was running.Ā
I checked the sidelights to avoid any headlight strangeness with main beam, although they were also dimmer.
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Sorry then, the limit of my imagination! Good luck!
Off to play with the multimeter after watching a YT video on how to measure amps.Ā
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If the lights go out in Southampton, I got it wrong. Sorry
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You measure current in series, so you need to 'break' into the circuit, connect the DVM (move the black lead to the socket on the left, select current on the knob). Check what the current should be as your meter only goes up to 10A.
Yeah voltage is only half the story. 13v is useless if ypu can only carry 0.1a through the cable.
A clamp meter will give you an idea of the current being pulled without having to pull stuff apart to get your multimeter in series.
Could be damaged/corroded wiring or a bad earth.
I guess easiest way ro check would be to run a live direct from the battery and around them to something nearby that's clean metal. if you get good output from the lamps then you know it's the wiring. it'll work in a modular way too so if you just run a perm 12v from the battery and use the original ground and get good output but a bad output using the original 12v then you know where the problem is.
Used to get similar on my mk2 golf because the wiring went from the battery to the dash then off to the lights. hijacking the wiring and putting a relay in solved the problem. short live from the battery to the relay. Relay behind the lights grounded to the chassis support.
I'd guess your 997 is slightly newer and probably more intelligently built though.
Hang on, replacing Xenons? Have you just put them in the old bulb holders? If so that implies you'd be using the factory ballasts which could lead to all sorts of issues!
The complexities of that combined with CANBUS and I'd be doing a lot of reading up.Ā
I've rewired an entire 90s Mazda, but I'm reluctant to even fit a new head unit to my wife's 987.2.
2005 Porsche. I can't get my multimeter in series, so apart from blinding myself by looking at the LED with the head light on I have proved nothing.
The same thing affects drivers and passengers side pairs of lights which appear to be on different cables which suggests it is not bad wiring in the car. Unless they are on a shared source somewhere in the car I suppose.
Also, both lamps use the same power cable and the same earth cable so if there was a fault I would expect it to affect both lamps.
The resistance on both headlights and main beams on both lamps is about 9.9 but about 45 for the side lights if that means anything. Same on both lamp units so I guess not.
SL on the originals were 5W bulbs compared to 15w LEDs but without knowing the amps they are getting I guess it doesn't help.
I am giving up for the night and going to my studio to paint insteadĀ
LEDs should draw a lot less currant than conventional bulbs.Ā Your sidelamps leds I very much doubt are 15w - they will be 15 w equivalents.Ā 15 w would be brighter than a 60w halogen
Check what submarined said and also check for bad earths
I have removed the old Xenon headlamp units and stored them safely in the attic.
I have added 2 pairs (4 lamps) of new LED headlights. The (limited) paperwork that came with the lamps states they are 2x15W high beam. 1x15W low beam and 12W DRL (not 15w as I wrote last night). 4,800LM for the big lamp and 2,100 for the little one.
I have the existing wires for Headlight, Main Beam, Sidelight and Earth going to a connector. The other half of the connector has a pair of each wire going separately to each lamp unit so that they work in parallel. The 4 wires for the Xenon ballast, ignitor etc are just terminated. The CAN bus is a bit upset at the moment reporting all sorts of lights issues but I will get that programmed out later.
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In the picture below, it shows main beam with the indicator switched on in the photo so that every LED in each lamp is on.
- The small lamp only has side lights across the middle and no indicator so is bright white which is correct.
- The small lamp has both LEDs brightly lit which is correct.
- The large lamp has the indicator lit up. With just the indicator on, it flashes correctly but when I switch the other lights on it simply lights up orange and stays on. This is partially correct - colour but no flashing.
- The large lamp has both LEDs lit but not very bright. This is partially correcty.
https://photos.app.goo.gl/6zYv5iUnjWZwP3ya9
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You could add a relay as suggested above without cutting the Porsche loom. Make up a small sub loom connected to the battery and new lights if a relay activated by the cars loom. Fit appropriate plugs to the relay so that it can be plugged into the existing loom.
I'd be wiring then through a relay that took a direct feed from the battery (with appropriate fuse)
The CAN bus is a bit upset at the moment reporting all sorts of lights issues but I will get that programmed out later.
I'd employ this approach and use the OEM wiring to trigger a relay(s), which is just a big switch. The OEM wiring just needs to open/close the contacts inside the relay and the power is taken directly from the battery
I'm still not sure why you want to make a Porsche look like a twin-headlamp Opel Manta B though š
I'm still not sure why you want to make a Porsche look like a twin-headlamp Opel Manta B though
Why not. Porsches are pretty common ā WCA is having fun creating something that is totally unique ā good on him. I wish I had a fraction of his skills.
"o make a Porsche look like a twin-headlamp Opel Manta B " - Better than the Chevette / Cavalier Coupe it was compared to previously šĀ