this morning i was driving down the road and noticed my head lights were on high beam but they were very dim, also noticed my dash lights were also dim along with my dome light when i turned it on. my seat belt light came on and it started buzzing like my dooor was open. i shut the truck off and it won't start, acts like dead battery but battery was replaced summer 2010. i figured alternator quit and drained my battery

 

First, charge the battery then test the alternator.
To test the alternator:

1. With the key turned on but the engine not running, use a digital multimeter to check the battery voltage. Then check the voltage at the alternator's positive output terminal (the big terminal, with a wire going to the battery's positive terminal) and a good ground on the engine. The two voltages should be the same; (about 12 volts) if they aren't, there's a bad connection.(possibly a fusible link)

2. If that tests OK, then start the engine and check battery voltage again. It should be at 14-15 volts. If it isn't, a full field test will determine wether it is the alternator or the regulator.

3. This test is for Chrysler alternators with external voltage regulators.(1974 to 1987 and not for computer controlled alternators) Jump full battery voltage from the positive battery post to the field terminal on the alternator.(the rotor) This bypasses the regulator. Start the truck. If the alternators main terminal now shows a high voltage (15-16 volts) the problem is in the regulator or its wiring. If the voltage is still just battery voltage the alternator is bad. CLOSELY MONITOR THE OUTPUT FROM THE ALTERNATOR DURING THIS TEST. DO NOT LET THE VOLTAGE EXCEED 16 VOLTS AND ONLY DO THIS LONG ENOUGH TO GET THE VOLTAGE READING.

Of course, if the belt is slipping or has come off (I've seen it happen) then even a good alternator won't charge the battery.

 

the belt did not come off and i'm pretty sure it isn't slipping because it still has the grip deals on the bottom side of the belt. at lunch i will check the voltage while not running and try to get it running to try the other stuff. i thought i did smell a faint burnt wire odor this morning

if i charge the battery and get it running then disconnect the positive side of the battery and it dies, doesn't that mean a bad alternator? i know nothing about voltage regulators... where is it and what does it look like?

 

if my battery was low enough to dim my lights wouldn't i get a false reading when doing the non running voltage test?

 

As I said: "First, charge the battery then test the alternator."

"if i charge the battery and get it running then disconnect the positive side of the battery and it dies, doesn't that mean a bad alternator? i know nothing about voltage regulators... where is it and what does it look like?"

A bad alternator, voltage regulator, or a wiring problem can all cause a no charge condition and can stop the truck when the battery is disconnected. That is why I gave you the proper procedure to isolate the problem. The voltage regulator is on the middle of the fire wall usually behind the air cleaner and is about a 4 inch box with one wire connector in the front. Do the tests and post the results and I will help you finish the trouble shooting process so that you don't waste money on unneeded parts.

 

If you find tthat it actually is the alt. Buy a rebuild kit (if available) from your local parts store. Because an alternator really never dies the brushes get worn out or the diode decides it's had enough

 

didn't have time to do much durning lunch but i did jump start it and drove it 2 miles or so to the shop. turn signals would not work and after i shut it off it would not start again. got the battery on the charger now

 

it was the alternator... charged battery - started truck - disconnected positive lead and it died- replaced alternator - will now run while battery is disconnected - tested bad also. new one was $40. should i replace the regulator? i've read articles saying it is necessary to replace it at time of alternator replacement, it's only $10 for a new one

 

if its only $10 i would probably replace it but i would keep the old one just in case the new ones ever fails.

 

all was well... headed home and the sucker over heated. tonight is my grandfather's birthday dinner so i won't have time to mess with it. thermostat is newer and i flushed it early spring '10. over flow was full of rusty water, probably end up taking hose off of discharge side of water pump to see if that is the problem. i think the ole dodge is gonna nickle and dime me to death