I Tried googling this issue and had no luck. So thought I'd post here in the hope someone else has had the same problem.

I get a weird "thump" through my speakers when I turn off my over head off road lights. Any one else have this problem before? Of course now that I am thinking about it maybe I have a bad ground somewhere. Or is this problem indicative of not enough amps flowing through the charging system? I tested the charging system when I installed all my lights by running the engine at idle and watched the voltage drop on my multi meter and even with all the aux lights on, the voltage drop was only .6 volts so I don' think it's an apmperage problem.

Any insight would be appreciated.

 

is the lights driven off the battery? do you have a relay? and actually that is a pretty good sized voltage drop, may want to get an alternator for an explorer, they came with a 120 and ours is a 90, same price and direct swap

 

I tapped power off the distro box in the engine compartment. All the lights are relayed. I find it odd because the noise is fairly recent it's only been within the last few weeks i have noticed it. I thought it might be the amp popping but I disconnected the sub woofer it drives and the noise comes from the 4 speakers running off my head unit. I haven't had a chance to check the ground for the lights in question yet, so I haven't fully ruled that out. As an aside I thought the 4.0L had the 120a alternator already, is that not the case?

 

sounds like a ground problem whether it be the speakers or head unit. double check your wiring.

 

+1 getting a good, solid ground is something that often gets overlooked.

 

x3 on the grounds.

What power did you tie in to in the engine compartment distribution box and what did you use it for ?

Does the popping come through if you shut off the Head Unit ?

Where does the main power come from for the lights ?
How many lights do you have on top ?
How many relays ?