LED light bar - LOUD high pitch noise

[guitarist982]

I'm wiring up my budget 42" "American" light bar behind the grill. When connected to an AUX switch (1 in this case), the light bar emits a LOUD, high pitch noise.

I've swapped to AUX 2, changed grounding points, tried direct to negative on battery, and with vehicle both on battery only and running. No changes to the sound. The only thing that stops the noise (and the bar operates as expected) is if I touch the leads directly to the positive and negative on the battery. Light output is unchanged through all this.

Any thoughts? Waiting to hear back from the manufacturer. Seems like a problem with the light bar itself but interesting it goes away when not powered through the AUX relays. No problems with my Rigid duallys or Chinese bar on the AUX switches.

Search didn't turn up anything so if I missed a thread let me know...

 

[2014RubyRed]

Just an idea, so don't kill me here, but are you using the same sized wire and what is going into the light bar itself? My point being, wondering if you are using a big enough power wire? May also want to inspect all the wire to make sure there isn't a crimped or damaged wire somewhere that you may have missed.

Just a couple of things to check......

 

[guitarist982]

It's worth double checking the wire gauge. The light bar came with its own harness, so I just cut that short and connected red to aux 1 passthrough and black to ground. That's when I get the noise. If I undo those connections and hook them directly to the battery, noise goes away. I would think that omits the light harness as the issue.

I didn't compare the aux wire gauge to the harness wire gauge, though, but they seemed similar. I'll double check tonight.

 

[AZEngineer]

Are you talking about a noise through the speakers, or the bar itself making a noise? I do not have an LED light bar but the LED driver circuit should not be making a loud noise.

 

[DCSVT1]

Hmmm...Obviously it shouldn't make any noise but if the noise goes away when connected directly to the battery then I would think (by far no auto electrical expert) it has to do with the switch. Did you change the fuse to match the rating of your bar?

 

[guitarist982]

The light bar itself is making the noise. Probably about a 5K HZ frequency and pretty damn loud.

The one thing I didn't try yet was wiring it up entirely with the provided harness, switch, relay, etc. I'll do that tonight and I guess that should tell me if if its the truck or light itself. I'm guessing light since I can move my other bar between aux 1 and 2 without issue, but different brand, watts, etc so kind of apples to oranges.

Didn't mess with fuses yet. Bar is 240W 20A

 

[guitarist982]

Ok ... So wired up with the harness/relay/switch that came with the light bar directly to the battery and there is a faint sound from the light bar - probably about 1/10th the level of when wired to the aux switch and would probably be drowned out while the truck is running. However, it's still 2 or 3 times as loud as when the bar is wired directly to the battery. Still waiting to hear back from the manufacturer and not holding my breath. Think it's the light or is there something else to look for?

 

[2014RubyRed]

Ok ... So wired up with the harness/relay/switch that came with the light bar directly to the battery and there is a faint sound from the light bar - probably about 1/10th the level of when wired to the aux switch and would probably be drowned out while the truck is running. However, it's still 2 or 3 times as loud as when the bar is wired directly to the battery. Still waiting to hear back from the manufacturer and not holding my breath. Think it's the light or is there something else to look for?

There's got to be something robbing power away from the light. LED's hum when they are starving for electricity. Do the wires plug into the back of the light or not? There and anywhere else where there is a connection/plug make sure you have some dielectric grease in there. It's amazing how good that stuff is with insuring good electric contact. Other than that, if the wires got directly into the back of the light, is there a chance that one of those wires got pinched somehow and when you are holding them up the battery they are straightened out. Maybe just fooling you a little......

 

[svt_ivan]

I have a similar issue with my cheap 42" ebay light placed in the same location. I originally had it on Aux switch #2 and heard that humming coming from the LED bar, but it wasn't loud enough to bother me so I let it be. Just recently I re-wired all my lighting and moved that same bar to Aux switch #1 and once again the humming is still there. What I did notice is that once I turn on my hood pods which are placed on Aux switch #2 the humming on the 42" led bar goes away, but as soon as I turn off the hood pods the humming returns. I guess I too have to go back and look into all my wiring.

 

[guitarist982]

There's got to be something robbing power away from the light. LED's hum when they are starving for electricity. Do the wires plug into the back of the light or not? There and anywhere else where there is a connection/plug make sure you have some dielectric grease in there. It's amazing how good that stuff is with insuring good electric contact. Other than that, if the wires got directly into the back of the light, is there a chance that one of those wires got pinched somehow and when you are holding them up the battery they are straightened out. Maybe just fooling you a little......

I agree, there's just not much there to be robbing it. There's about a 2 ft. lead coming off the light into a waterproof connector. I've got about 2 more ft. of wire on the other side of the plug that I'm connecting up to the aux. All the wiring 'seems' to be in good order and there isn't really much movement between tests. With the 4 ft. of wiring in the above install is where I get the most noise from the light. When that same 4 ft. is connected direct to battery, noise is eliminated. When I spliced the supplied light bar harness back in (and add about 18 more ft. of wiring and splices) the noise is significantly less than when on the aux switch.

I guess next step is to eliminate the waterproof connector and hard wire the light. Does not seem as high a quality as the one on the duallys so that could be contributing.

I have a similar issue with my cheap 42" ebay light placed in the same location. I originally had it on Aux switch #2 and heard that humming coming from the LED bar, but it wasn't loud enough to bother me so I let it be. Just recently I re-wired all my lighting and moved that same bar to Aux switch #1 and once again the humming is still there. What I did notice is that once I turn on my hood pods which are placed on Aux switch #2 the humming on the 42" led bar goes away, but as soon as I turn off the hood pods the humming returns. I guess I too have to go back and look into all my wiring.

Interesting your noise went away. I tried various combos of aux switches on and even stereo and A/C on/off to see if something external was contributing. No change for me.