i just installed 4-10" subs and a 1100 watt amp in my expedition the problem that created is my dome lights are on whenever the truck is running however they are very dim. when i rev up the truck the lights brighten up. i replaced the stock battery with an optima red top hoping that would fix it but i didnt. i also have a dvd player in dash tv and cd changer that have been installed 2 months before i hade any problems.

 

I'm not sure I understand what the problem is: is it that the dome lights are always on, or that when they're on, they're dim?

If they're dim when the truck is idling, but they brighten up with engine RPM, something is creating a HUGE power leak. Is this true of the dome lights even when your sound system is powered off? If it is, something's really amiss here. If it's only when the sound system is on, that narrows it down a little...I'd check to make sure that sufficiently big wires were used for the power installation for starters.

What's really strange is that revving the engine brightens the lights...the additional alternator output at high RPMs is nothing compared to the discharge capability of that Optima battery. Is the battery properly connected? Pay special attention to the ground wire (at both ends)...it may be that the battery's unable to deliver its juice due to some bad wiring.

Let us know what develops...good luck.

mz

 

the lights are always on when the truck is on but very dim. i did use a 4 gauge stinger wiring kit. i was told that would be big enough. but maybe its not. when you said to pay attention to the ground on both ends did you mean at the battery and amp? do you think that a cap may fix it?

 

The dome lights are always on...I assume that you've checked the on/off switch(es) at the lamps...?

Second, I'd check all of the door switches to make sure that they haven't failed in the "on" position. You may need a multimeter for this, but it might be possible to discover something just by playing with each of them.

If this doesn't reveal anything, then somehow a "hot" wire must be touching the dome wire past the points of the switches. I don't know anything about the wire routing for the dome lights, but you might want to check that your power wires for the amps aren't touching anything they shouldn't be.

The following points won't fix the dome light problem, but are noteworthy nonetheless.

Wiring: 4 gauge may or may not be sufficient for a 1000W load; it depends on the length of the wire run. I doubt, though, that the wire gauge is causing this problem; just something to re-check at some point.

Checking grounds: I meant to check the battery ground at the battery and at the chassis connection. Also, check both wires running to the amp. It's uncommon for wire to go bad, especially 4 gauge, so pay more attention to the termination points. Make sure things are clean, tight and have lots of contact area.

It really seems unlikely that the amp install is directly responsible for the dome light question. If you want to prove this to yourself, remove the amp power wires from the battery and check the dome lights.

A stiffening cap: I am personally not a big fan of these, and in any event, it's not going to fix your dome light issue. Save your $$ for the time being.

Let us know what's going on.

 

Ok, here is a bunch of stuff.
I had this problem in a 1997 Expedition. I've always done my OWN stereo/amp installs but I bought a new head unit from Best Buy and they were featuring FREE intall with FREE install kits, if you had it intalled the SAME DAY. So I said, what the heck, and had them do it. MISTAKE.

I don't know ifyou installed a new head unit or not, but this is what happend to my truck.

I had them install the new head unit in my EXPY. Well, when I got home that night I noticed that my dome lights were on slightly, and they would too increase in brightness when the truck was revved up.

Here is what I found. Aparantly, the guys who were wring my truck didn't know anything about my head unit and how to wire it into the truck.

The took the (normally blue) REMOTE AMP TURN ON wire coming OUT of my headunit and hooked it to the ILLUMINATION wire coming out of my truck's wiring harness.
This caused a 12 volt feed to go back into the headlight switch.
The headlight switch is resistered in several places to allow the proper voltage to go to the backlighting of the factory radio. Well what ended up happening is that it was forcing the 12volts into the back side of the resistered circuit, and it ended up melting a few components in the headlight switch. Then I figure, (although I am am not sure) that the the small voltage difference between Idle and Fast Idle was enough of a difference that when amplified (or reduced) through the resisters, it changed the voltage going to the dome light circuit.
So what I am basically saying is check to make sure that your headunit is corrcted correctly. No stray wires, everything going to where it is supposed to go. If you find things amiss, be prepared to buy a new headlight switch.

BTW, 4 guage is PLENTY for this configuration. 1100 Watt Amp is PEAK and even if you were constanly drawing this much current, 4 guage would be fine.
Caps help if you experience voltage problems with your Amp, if you need it, use it, if you don;t then don't. Simple as that.
Thanks,
MK