ultramad Posted May 13, 2017 Share Posted May 13, 2017 Hi,I recently installed a 50" Curved light bar to my 2000 Terrano with a 16 gauge wiring kit that came with it with 40A relay and a 30A fuse It works good when the truck isn't moving but as soon as I start driving and get to 50kph+ the light bar dims down for some reason.I tried changing the wiring to 14 gauge but still the same problem, just wondering if any of you guys here may have any idea to what is causing this problem. Link to comment Share on other sites More sharing options...
onespiritbrain Posted May 13, 2017 Share Posted May 13, 2017 Do your headlights follow suit? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
ultramad Posted May 13, 2017 Author Share Posted May 13, 2017 nope, headlights stay full brightness same if I turn on the fog lights Link to comment Share on other sites More sharing options...
Citron Posted May 13, 2017 Share Posted May 13, 2017 (edited) How is it wired? Where are you getting the 12v, direct from battery, or from a different circuit? How are you switching it, on a dedicated switch or using the headlight switch? Just guessing without a schematic or knowing any information, I would say the circuit you are using for 12v has something else on it that is drawing power and dimming the light. I can't think what it would be that is speed related though. Any other info, was it raining when this happens? Does it happen all the time? When you slow down below 50 or if you speed up above 50 does it brighten? If you are parked and you change RPM, does the light output change? Edited May 13, 2017 by Citron 1 Link to comment Share on other sites More sharing options...
ultramad Posted May 13, 2017 Author Share Posted May 13, 2017 It is wired directly to the battery for the 12V feed and is on a dedicated ARB style switch, there has been no rain when this happens and it happens all the time at the same speed, If I slow down below 50 it comes back to full brightness. I haven't yet tested it parked and changing RPM, but will do that tonight if I can't find the cause.I'm usually quite good with electrical stuff in vehicles but this whole speed thing affecting just the light bar has me confused. Link to comment Share on other sites More sharing options...
ultramad Posted May 13, 2017 Author Share Posted May 13, 2017 Ok, so i've tested it by being parked and increasing the rpm and it stay's full brightness.It's on a temporary mount at the moment until I get my roof racks and light bar mounting brackets in the next few days. I'm actually wondering now if it's moving on the temporary mount and pointing to the sky when I hit speeds of 50+ appearing to go dim. I will get someone to look if this is the case today. Link to comment Share on other sites More sharing options...
onespiritbrain Posted May 13, 2017 Share Posted May 13, 2017 Does it just dim down or does it flicker and dim intermittently? What brand light bar is this that you have? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
ultramad Posted May 13, 2017 Author Share Posted May 13, 2017 It doesn't flicker at all just instantly goes dim, I replaced the 70A alternator last year when that died with a 90A alternator.Brand new battery 06/16 which is 730CCAlight bar doesn't have a brand name on it, so unsure on who made it. Link to comment Share on other sites More sharing options...
jyeager Posted May 14, 2017 Share Posted May 14, 2017 It definitely sounds as if it's related to the wind speed. So keep investigating that route. Link to comment Share on other sites More sharing options...
Slartibartfast Posted May 14, 2017 Share Posted May 14, 2017 Huh. So it's fully bright until you hit 50, then it goes dim immediately. Bizarre. I would expect flickering if this was a wind issue, and having wind suddenly be a problem at a specific speed (and an even number at that) seems unlikely. Bending back on the mounts is possible, though I'd expect you to notice it flickering as it buffeted around in the wind. I also wonder if it might be picking up vibration from the truck and it just happens to hit the right frequency at 50 to get the bar wobbling around enough to spread the light and make it seem dimmer. If the lightbar is easy to dismount, I'd throw it in the footwell (maybe wrap a bag around it so it doesn't blind you) and then go hit 50 again. If it doesn't dim, your problem is mechanical. If it still dims, I'd bet on electrical issues. (Another good test would be to check for voltage across the light bar--as close to the bar as possible so you'll catch any issues with your wiring. If the voltage drops when the light dims, it's definitely electrical.) Where's the light grounded? I'm thinking along similar lines to what Citron suggested, that it's sharing a flaky ground with something else that draws power when you hit 50. A while back this guy reported that his JDM Terrano had some kind of warning buzzer built into the cluster that kicked on at 50. He reported 50 MPH, not your 50 KPH, and I've never heard of anyone else dealing with that same buzzer, but I figured I'd throw it out there anyway on the off chance it's a Terrano thing and you've grounded the light bar to something questionable in the dash. Even if you're pretty sure of your ground, you could run a test lead from it to another known good ground just to rule out the ground as your issue. The only other dumb idea I've got right now is that something's causing interference in your electrical system--not necessarily a load, just electrical noise that's confusing the driver circuitry for the LEDs. I consider this about as long a shot as the speed buzzer, but if you run out of theories that make sense, you could try testing the light bar off a separate 12v source (lawn tractor battery or something). If it still dims at 50, then there's that dumb idea ruled out. 1 Link to comment Share on other sites More sharing options...
ultramad Posted May 14, 2017 Author Share Posted May 14, 2017 Found the problem by holding my hand out the window on it until I hit 50, once I hit 50 the whole light bar tilts right back pretty much instantly. This will be fixed in the next few days when the actual roof racks and mounts I have ordered arrive. It's currently mounted on the old luggage cover that was in the boot. 2 Link to comment Share on other sites More sharing options...
Slartibartfast Posted May 14, 2017 Share Posted May 14, 2017 LOL good to hear it was a simple solution! Link to comment Share on other sites More sharing options...
Citron Posted May 14, 2017 Share Posted May 14, 2017 Yes, thanks for updating the thread. Link to comment Share on other sites More sharing options...
Mrelcocko Posted May 28, 2017 Share Posted May 28, 2017 Great that you found the problem. I myself wouldn't wire the light bar direct. Using a relay is the better route. Just saying. Sent from my SM-G530T using Tapatalk Link to comment Share on other sites More sharing options...
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