k heres my prob , and any details i can think of that might help ,

1st '89 f-250 xlt lariat
next my prob is that my battery meter will sit very low , and drop little bits for everything i do , roll up windows , turn on blinker , a/c , anything , if i do a few things at the same time , it will put it into the red

now once anda while i will do some work on it , and it will be gone , it will sit right in the middle and i can power everything with no problem , a/c on lights on , rolling windows and everything , it wont move , but then ill drive for a bit , and it will come back

another thing that might be related , but im not too saavy on electrical troubleshooting , is that sometimes , only one headlight will work , drive a bit it works , but it usually doesnt , and i cant figure out why , the wires are fine all the way through and the driver side headlught always works no matter what

anyone know where i should start?

 

89f250xltlariat,
I would check the very basic stuff first. Intermittent and/or weird electrical problems can often be traced to bad grounds and in general bad connections.

Loose grounds and connections
Make sure the battery cables and terminals are fine no corrosion and tight. Check all the grounds at the engine block and upper intake manifold, etc. Remove clean and retighten battery cable terminals and engine ground

Voltage Drop
You should not have any voltage drop between the terminal and and the battery post.

Wiring
Do the wires appear OK or old and frayed, is there corrosion? How about connectors?

Hope this helps

 

Having slight movement of the voltage meter while doing something is normal.

Do you have a voltmeter?

The place to start is to check your battery voltage and alternator output. A strong battery will have about 12.5v unloaded. Have someone start the truck and observe the voltage. It shouldn't drop below 10 volts. Once the truck is running the alternator should kick in and supply about 14.2-14.5 volts. Anything under 14 is suspect.

Once you pass that test, you can be assured that your battery and alternator are working properly.

One note, on older trucks like these the battery cables are often neglected and can cause all sorts of problems. It is a good idea to replace old crappy battery cables.

Next time your headlight doesn't work, take the electrical plug off the bulb and check to see if you have 12v of power there. If you don't, you know the problem is upstream. If you do have 12v, than you must have a bad connection at the bulb or a bad bulb.

It has happened where the filament is broken but is resting on another piece of the filament and therefore still makes an electrical conection and alluminates. Hit a pothole and the filament separates and the light goes out.


That should get ya started.

 

koo , ok fixed my headlight prob , neds a new bulb ,

as for my draw , all new cables , new battery , and alternator , and when the draw is gone , the battery meter shows no volt drop even if i run everything , it stays right under the middle mark ,

but when the draw is there , it sits at the second mark with nothing on , and will drop as low as the red zone depending on what i have on, like if i have a/c on , headlights , turnsignal , then i roll down a window , it will drop into the red , truck runs fine , but the electrical prob is bugging me , not a huge issue , just bothersome, took my stereo out coz of it , with the stereo on i cant do anything if the draw is present

 

0 guage wires on battery , in case anyone was gonna ask


and ya , i work on a/c's so i have all kindsa meters , multimeter , ampmeter , and more im sure i wont need for this