New lightforces... Gas gauge keeps dropping??

So recently I picked up a set of lightforce 140 lances to add to my front bumper in addition the the two 55w hid converted 170s already on there. I wired everything up with the two lights, a relay, and a cheap switch. I wanted to be able to turn the lights on regardless of the truck being on or not so all power is coming directly from the battery.

Here's the issue: whenever I turn the lights on the needle on my gas gauge drops to about the 1/4 tank mark. It doesn't matter if the tank is full, half full, it still drops. I have good grounds on the lights and the relay, and I didn't tap into any existing circuits, only the battery.

This doesn't happen with my other lightforces which are wired the same way. The only difference is the 170s are 55w apiece and the new lights are 75w apiece.

Any ideas on what's going wrong? Is my alternator just on it's last legs and can't keep up with the added draw? I'm pretty lost as far as what the problem could be..

 

Anyone?

 

sounds like you don't have enough power to run everything.

 

If you don't have 13 amps available something is really wrong so I'm pretty doubtful you have anything wrong with your battery or charging system. Nor do I believe that would affect your gauge.

That's a very odd problem.

I would look at the grounds for the fuel float sender/gauge. And again at the grounds for your lights/relay/switch.

I'd also clean and check the grounds from battery - to engine and body as well as the terminal.

 

Ill go through and check ground for everything again.

Also I have a 10" sub hooked up to a 600w amp as well. Forgot to mention that in the op.

Although i tried disconnecting the amp from the battery and still had the same problem

 

Well does it only happen when you're running everything or if you leave all the accessories off and just turn on the lights will it still happen?

I think regardless it's nothing to do with charging system.

 

It happens with the truck running and not running, with the sub/amp connected or disconnected, and happens with the other lightforces on or off.

 

Checked all the grounds on my lights, relay, and switch... Still have the problem.

Any other ideas?

 

grounds on your sender/gauge?

 

Unplug the switch/wires to switch and jump the terminal with a jumper wire, what happens?

 

Did you tap any wires in the cab to power the switch?

 

Ill give that a try tonight after work. You mean the terminal on the relay correct?

Nope. I didn't tap any existing wiring. Just the battery

 

Basically just bypass the switch and wiring going into cab, and switch it right at the relay. I'm very doubtful but I was just wondering if it's possible that RF is interfering with your gauge somehow, not even sure it's possible but it's so easy to try that that I figure why not.

 

Okay ill give that a shot and check the grounds on the sender/gauge too. I got all my stuff to convert them to hid so I might pull them off and do that in the next couple days and see if the problem is still there after that. I would assume it would be.

 

Well I finished converting the new lightforces to 55w HID and hooked everything back up... No more dropping gas gauge! so it had to have been something with the grounds on the lights is my guess. Even though they seemed like good grounds to me.