High beams crash then battery drains? Need truck advice

virginia shadow,
Chances are good that the alternator is bad. Vehicles now days are programmed to start shutting down their systems in the least harmful way if the alternator craps out. I had it happen to me while on the interstate, at night. I didn't know what was going on until even my low beams went out. Altenator was bad.

Another thing, vehicles don't need to have a battery in order to stay running once started as long as the alternator is working. A cheap test is to disconnect the battery while the vehicle is running. If it dies, the alternator is not working properly.

 

Thank you guys so much...BIG help. Gonna get started on it tonight.

 

All you need to test the alternator is a DC volt meter, if the voltage from the negative and positive battery posts is under 13 volts the alternator is bad

 

Whenever I have vehicle issues, the first thing I do is check the oil, if that comes out ok, I have a seat an open a beer as I've exhausted my abilities to deal with vehicle issues. Now this doesn't help your situation, but it does reinforce the need to have some beer on hand at all times.

 

Haha sounds like me too!

 

Rebuilt alternator plus labor....$500ish?

 

I remember getting rebuilt alternators for my IHs only being about $40.00 and like 4 easy bolts. Lol

 

Ouch, heck alternators are pretty easy to install if you have a garage and tools, u tube really helps too

 

soooper easy to swap an alternator!!

 

It has been a while since I bought one, but I remember paying less than $100 and installing myself, and I am not handy.

 

ok cool....Ill try to do it myself if that in fact is the problem

 

Don't forget the beer.

 

Sounds like a lot of people have already chimed in with some good options. Continuous battery issues would be a check the charging system first. I'd also give the dealership a call, see if there are any recalls or TSB's (technical service bulletins) for the issue, you may get a free fix even if out of warranty especially if there is an associated risk of fire. Usually you would have gotten a notice in the mail though.


If alternator does indeed test good, it sounds like you have a key off drain. Can be very simple or very expensive, the expensive part is diagnostic labor, key off drains are troublesome to track down and they will charge hourly labor rates until found and then another parts and labor cost to repair.

Again if the alternator does test good then start isolating known issues. Pull the relay for the high beams (if it has one) and swap with another with the same part number labeled on it. See if they work then. If they do pretty simple and cost effective repair th at hopefully remedies the issue.

One question I would always ask is if the vehicle owner uses the tilt steering all the time. With everything being on the steering wheel or column that tilt function can wreak havoc on the wiring harnesses.

 

We've got a 96 Dodge Ram work truck that the lights only turn on when the steering wheel is tilted in a certain position.

 

That's handy.

 

Its not the alternator. Truck ran fine with battery detached. hmmm

 

Looks like you have separate fuses for each headlight high and low beam. I'd pull the two high beam fuses since those are problematic. See if the battery is still charged in the morning.

Process of elimination

 

At least the problem isn't intermediate, electrical problems that are not constant are maddening. Go buy more beer, you are going in.

 

Pulled the fuses for high beams. Look good. Look like my running lights are not working either. Yuck. Going to read up some.

 

One thing pulling the fuses will do is isolate which side of the circuit they are on, since the fuses are good you know it's not a ground fault short on the headlamp side.

Do you use the tilt function on the steering wheel often?

Did you do anything differently recently? Three point turn about in a ditch with brush or something while hunting. Any thing that could have snagged some wiring around the bumper/fender area on either of the 4 corners?

Key off drains are hard to track down, especially when they happen all of a sudden. Sunday everything is fine, Monday problems showed themselves, was there anything between that while didn't seem.significant at the time was different than the norm. Potholes, new electronic put in, old one taken out, loaned it to a friend etc..

They can be frustrating

Wish I still worked in a shop, I'd pull up the wiring schematic and find common denominators between the high beams and running lights.

Could be a simple relay stuck closed, dimmer/turn signal switch assembly