Battery light , fuel gauge not working

what lights car is chock-o-block full of lamps. lights.
HEAD LAMPS?
WELL REMOVING THE BAD ALTERNATOR BLUE UP FUSES
THE SERVICE GUIDE ON ALL CARS MADE SAYS
STEP1
REMOVE BATTERY NEG LUG FIRST (OR boom)
FORGET TRACTION, BUT 12VDC POWER FEEDS ARE WEAK
AND WHEN WEAK AT 10VDC THE COMPUTERS ALL LIE
THE ALT IS BAD. OR BATTERY SHORTED.
WHEN YOU BLEW UP THE HUGE FUSE, THAT RENDERS THE CHARGE LAMP DEAD. the cure is stop blowing up fuses!!!!!!!

if at was good battery voltage at idle or 85mph is 13. to 15vdc
yours will fail this test.
one fuse blown is the 100amp huge fuse to the Alternators ,huge 4 gauge, wired main power lug, you blew that up.
or using wrong alternator.
on some cars Vast the PCM runs the ALT, the PCM is the regulator
so guessing alts wrong is super bad here.

The fuel gauge sensor in your tank has stopped working or you a connection to it. Your local repair shop will be able to help you. Good luck.

there is a regulator for the display brightness, you may have it turn'd down or it has stopped working;. it controls the brightness at which the dash lights are. usually has a speedo sign on it. goes up and down. it works with the main light and is conecter to them on the same lighting board if it has gone then a new light swtch control switch will be needed.

check for the alternator failure. probably not charging.

This sounds similar to my problem yesterday, where the lights were blinking on and off and the gauges going up and doing like crazy. It was the battery has lost most of its charge (only had 230CCA out of the expected 800).

Fortunately, the battery was still under warranty.

No , it's not the PCM . Battery light on means a problem with the charging system (alternator) And maybe the insturment cluster . Before you start replacing parts the vehicle doesn't need ,take it to a qualified repair shop .cost less in the long run .

you have flattened the battery ,now charge the battery for 24 hrs then it will crank ,if it still doesnt start then check the fuel pressure 55lbs on the common fuel rail their is a tyre valve ,connect a pressure gauge to this valve and see what you read

You said some of the warning lights come on. Then you can get a free scan at Autozone, Advance, or Oreilys. If this is a 2004-2008 Ford truck, there were some issues with the charging circuit cutting out due to a low battery charge.

It sounds like the Ignition switch is cutting out. You can get full chassis wiring diagrams and fusebox layouts at Autozone.com after registering with the site for FREE. Look at your diagrams and pay attention to the Relays that are activated by the keyswitch.

The RPM increase is normal when the Alternator is completely free-wheeling. There can be a hotwire to the Alternator brushes which runs from the keyswitch to the Alternator. If this is cutting out, the Alternator can not charge.

Look at how the Temperature gauge receives its power. It is a clue to which Relay is bad or ground wire is loose. Especially if you still have a working fuel gauge.

The loading up with a discharging Battery is normal. Consider that all the electric controls work directly and proportionately off of the 13-14 Volt range when charging. Your fuel mix, timing, are all related to the Voltage feedback and what starts low, stays low corrupting those settings.

The diagrams will give you a better tool to work with if you cannot drive for a scan. Just view the chassis voltage as the Target. If you drop below the battery voltage when you test the chassis voltage there has to be a reason.

check the alternator charge level .
check the battery + and - are not lossing
if nothing then you have wiring short

usually its the negitive terminal you disconnect for about 30 secs. tyr that. if that doesnt do it, its possible you shorted something out.