2 fog lights = loud grinding, screeching noise

[noob4x4]

I installed two hid fog lights (4 lights) with two sperate switches both work well when turned on one at a time. Once i turn on both at the same time, it makes this really loud screeching/grinding noise and the lights flicker.. I immediately shut'em off fearing something might blow.. What am i doing wrong??

 

[Lt.Jim]

What part was making the noise lights, switches, engine?

 

[noob4x4]

It came from under the hood, I dont think it was the engine, switches, or lights.. It came from under the left side of the hood i think. I own a 01 Expedition... It was really loud..

 

[Lt.Jim]

It sounds like when both sets are turned on there is some sort of short going on. I would go through and check all the wiring to make sure no bare wire is touching anything or that wires are not crossed.

 

[hunterdan]

Could it be too much draw on the alternator? Causing the alternator to work harder. Whats the amp rating on the lights? What kind of shape is your battery in?

Dan

 

[noob4x4]

Battery is fairly good, i've replaced it about 5 months ago, the lights are both HIDs, i'm not sure what the amp ratings are... I think the wiring is bad cuz my headlights(low beams) are also hids, when i turn on headlights + fog1, works well, headlights +fog2, works well, when i turn headlights off and turn on both fog lights, that noise straight out of jurassic park again.. Since it works fine with headlights + any fog, i dont think its the power issue but rather bad wiring..?

 

[Jason94sport]

How do you have the lights hooked up? Are they going to relays? Are they direct wire? Are you using switched power? From what source if you are?

 

[Bill Kemp]

If it makes a bad noise...Dont do it!
Its probably due the the very high start up voltage that the HIDs require. Once lit the voltage is minamel but at start up is is significant. Could be your alt. making noise and youe belt slipping..

 

[noob4x4]

I'm using two seperate fog light harnesses with switches and relay.. one of the harness draws power from battery to relay to lights, then from relay to switch and switch also needs power for led and has ground wire... The other one is similar setup but this one has 2 grounds from relay, one from the lights and other from relay, with another ground for switch...

 

[Jason94sport]

What are you tapping into for your switched power source? Or are they running direct off the battery.

Also does it happen with the engine on/off or both?

 

[noob4x4]

i spliced into my parking lights for both switches so that the switch only works when parking lights are on, thus all the fogs would turn off when i turn off my parking lights. It happens both, when car is turned on and off...

 

[Jason94sport]

Ok so you know it's not the alt because it happens when it's off. I would say check your wiring & grounds. Start out simple. Disconnect them both & then hook up 1 set & then go from there. You may have a bad set, bulb, relay, or bad wires. May also want to run the switched wire to the battery directly to test. There could be a problem in hooking into the parking light wires with current.