Any truck mechanics out there?

[almac16]

My truck started acting up on the way home from work today. Battery light came on and low charge on the indicator.

Checked the battery it's getting 11.5 volts when off and 10.9 volts when idling.

Manual says it should be around 12 when off and 14-15 when running.....so something isn't right.

I didn't have anyone to rev it up but it seems if I have the RPMs up it shows that it is chargin fine and the battery light goes out.

Any ideas? Could it be the voltage regulator? Or just a bad alternator.

I priced the alternate at $250CDN at Canadian Tire (only place open at this time of day)

Help!

[MTS]

alatanator more than likely, go to NAPA autoparts and take your old one, they will give a 80$ back for the core of the old one on the new one, and if it dosnt solve the problem you can take it back

[almac16]

alatanator more than likely, go to NAPA autoparts and take your old one, they will give a 80$ back for the core of the old one on the new one, and if it dosnt solve the problem you can take it back

Are you sure you can take it back? most places won't let you return electrical parts

[Pistonhead]

Its probably the alternator. Places take back starters and alternators so that they can rebuild the core and re-sell it. Napa should have the part. If the truck is a GMC/Chevy the alternators off of 12v electrical system fleetline series oliver tractors interchange with the truck alternators.

[almac16]

Maybe I should have said...... it's a 1998 F-150 4x4 with the 4.6L in it.

[PowerTrike]

Battery isn't being charged like is supposed to:
(probably alternator like they said)

11.5V: Almost 12, normal
10.9 when running: some voltage is getting used by accesories but its not getting put back. My jeep gives about 16-17 volts when its running. Same thing happened to me about a year ago (I was only getting 9.2V or somthing when running) it was the alternator...

[almac16]

this sucks, but it looks like I will be putting in a new alternator tommorrow night. I will have to look around for a cheaper place !

Thanks for the help guys

[bassman]

IRON MAIDEN \m/

Alternator- www.ebay.com

[grundlegrabber]

ALternator is shot. Check all your electrical connections (battery terminals, starter wires, solenoid connections, grounds, alternator wire), make sure they are all clean and tight. If they are, replace the alternator. You should see 14.2 to 14.6 volts at idle, turn all lights and accessories on and it shouldn't drop below 13.8v with a good alternator. Make sure your battery is charged up before running it with the new alternator. It's always a good idea to replace the regulator at the same time, if you have the extra $$. Many older fords had separate regulator, GMs had regulator built in to alternator (most vehicles are this way). Use a quality alternator. There are some cheapo remans out there, they are guaranteed to go bad again soon. Your Napa or Carquest store might sell brand new ones (not reman), they're a bit more expensive but worth it in my opinion. A bad alternator will leave you dead on the road.

[almac16]

IRON MAIDEN \m/

Alternator- www.ebay.com

Won't be much help to have it running by tomorrow night

[max]

12.66 is full charge on a battery. 12 is about 25%. this is with car off. anything under 12.44 you can start to get electrical issues. if you have a newer computer controled truck. good luck.
max

[nate b]

most parts stores will test your alternator for you. I'd get one from a junkyard, I dont care for reman parts.

[Pistonhead]

Yeah most places will put your alternator on a growler and test it for you, but it sounds like you just need a new one.

[Name Brand]

Vehicles have two power sources, the battery and the alternator. The battery is there to provide power to start the vehicle, the alternator provides power when the vehicles engine is running. The vehicle can run from both as well.

Loosen both battery cables, start the truck, let it run and disconnect both cables from the battery. If the vehicle stops running; the alternator is bad and the vehicle was running of the power in the battery. If the vehicle keeps running, the alternator is good.

[almac16]

Bought a 130amp and tossed that in, plenty of charge now.

Thanks for the input guys