Is it the alternator?

Status
Not open for further replies.
Joined
Jan 27, 2004
Messages
4,131
Location
Richmond, VA
My 96 F150 started losing juice on the electrical system on Thursday. Drove it to work on Friday (had no choice) and by the time i got there the battery was dead. Got a jump and made it home but everything was dying, even the speedometer didn't work. Put the battery on a charger overnight and the truck runs fine now. I'm about to run up to AutoZone to get a new alternator but just wanted ya'lls opinion on whether there is anything else it could be.

95 F150 5.0 5 speed standard cab 2wd long bed 97k miles. A few dents and scratches but man she is pretty
smile.gif
 
Yep... prolly the alternator. If the battery dies while driving it's probably a bad alternator. If the battery is dead when you start it.... it's probably a bad battery.
 
Did you check the voltage while the engine was running?
It sure sounds like it's the alternator but maybe you have an extremely corroded battery clamp on your battery cable.
My friend had one which was nearly 100% corrosion inside the swag.

Also, what's all the 12V stuff on the firewall of that truck? A pal has a '97 and there are no straight shots between the alternator-battery-starter.
Battery voltage goes into that assembly on the firewall (forward of the passenger's knees.
It's full of relays and heaven knows what. Is there something in there which can stick?
 
Originally Posted By: Barkleymut

95 F150 5.0 5 speed standard cab 2wd long bed 97k miles.


I've owned quite a few Ford trucks from that era (I still own a '97 F250) and I'd always have alternator problems between 100K-130K miles. Of course, I live on a dusty gravel road, so that may be why they failed that early. IMO, if the alternator has not failed, it will happen soon, so I'd have the thing rebuilt or replaced now.
 
From what I read earlier (not on BITOG) there is a huge fuse in there. I'm a rookie when it comes to electrical stuff.
 
Originally Posted By: Barkleymut
My 96 F150 started losing juice on the electrical system on Thursday. Drove it to work on Friday (had no choice) and by the time i got there the battery was dead. Got a jump and made it home but everything was dying, even the speedometer didn't work. Put the battery on a charger overnight and the truck runs fine now. I'm about to run up to AutoZone to get a new alternator but just wanted ya'lls opinion on whether there is anything else it could be.

95 F150 5.0 5 speed standard cab 2wd long bed 97k miles. A few dents and scratches but man she is pretty
smile.gif



Have them test the old one AND if you buy a replacement, have it tested before you leave the store. It's a real pain to get home, install something, only to find out it too was bad.
 
If this Ford has the infamous 2 plug alternator,REPLACE the elongated squared off plug with a new one installing the new unit.Good units will give you one in the box.Plenty of 80s and 90s Fords have burnt up thanks to that lousy connection.
 
Couple of things. Yes, it's prolly the alternator. But, the truck is getting a bit long in the tooth (20 years) so I'd say the ground side was getting crevice corrosion, minor salt bridges, etc.

So all the stuff on the positive side has voltage to help it do whatever. But all that current has to return to source through the ground side with 0 voltage (it's been used up by the device). Not as easy to do ...

So for all Fords over about 10 years old, I always add new grounds. Say #4 cable with crimped and soldered lugs between the Bat (-) and the alternator bracket. Then another say #8 between the intake manifold (any convenient bolt) and the fire-wall (a hood hinge bolt works well). Same crimped and soldered lugs assembly.

There are lots of old Fords that will not charge the battery fully because the built-in regulator can not see the real ground, but see's an offset ground based on how much resistance it has on the ground-path back to the battery.

A new one from the Bat (-) clamp bolt/nut to the alternator mount eliminates that resistance and makes the regulator much more effective. Adding these two new grounds will make the whole system work better and it will start and run much easier. Has for every one I've done, and that's more than a dozen in the last ten years of so ...
 
Check all connections first ... All of them including the ones on the alternator check the voltage on the battery and start it up and make sure it is charging with a voltmeter..Sometimes its a bad connection but the alternator could be bad also...How old is the battery? A weak or bad battery can cause problems also.
 
Problem with checking and cleaning some of these Fords is that they buried the main ground point on a bolt on the side of the engine block right above the cross-member. It can not be easily accessed, is often rusted solid, so it never gets cleaned or serviced ... It's one of those "what was Ford thinking" things that we have to work around ...
frown.gif


But I agree with everything CrazyOilDude says above
smile.gif
 
Originally Posted By: Barkleymut
Got a jump and made it home but everything was dying, even the speedometer didn't work. Put the battery on a charger overnight and the truck runs fine now. )


Aren't you glad it triaged itself and let itself still run.

The stuff you *need* gets by on 8-ish volts, which the battery dips to when cranking to start on a cold day.
 
I had a similar problem with a similar vintage 4.9L/5-speed F-150 a little while back. It was slowly dying electrically when driving...lost the digital odo, then the speedo and all other gauges, then a couple miles later the truck just died. Put a battery in it and it was fine for a few days, then it started doing it again, so put an alternator in it. Problem solved.
 
Originally Posted By: 01rangerxl
I had a similar problem with a similar vintage 4.9L/5-speed F-150 a little while back. It was slowly dying electrically when driving...lost the digital odo, then the speedo and all other gauges, then a couple miles later the truck just died. Put a battery in it and it was fine for a few days, then it started doing it again, so put an alternator in it. Problem solved.


My 1989 F-150, 4.9/manual just up and died while on the highway. It had "real" gauges back then and I watched the voltage drop until the truck just died. A new alternator fixed it. The alternator on my 2002 F-150 started triggering the red ALT light when the truck was at and above 2500 rpm, weird. A reman from NAPA replaced it and it's been fine ever since.

Whimsey
 
Status
Not open for further replies.
Back
Top