Truck dies with headlights on

2001 Tacoma 2.7l, 280,XXX. I recently changed the alternator bushings and voltage regulator. My wife was driving the truck the other day and she went over a speed bump and the truck shut off. She started it back up and it ran normal. The other night as she left work, she turned on the truck and turned on the headlamps and the truck died again. This time it did not start back up. Everything was off, no power. When I picked her up, the starter turned but the motor did not fire up. Eventually, after messing with the fuses, the truck started right up, however, when I turned in the headlamps it shut off again! It started back up with no problem. Any idea would could be causing this? I replaced the parts in the alternator because I had a battery light on and a test at the parts store confirmed bad alternator. I feel like something may be loose but the headlamp symptoms kind of mystifies me. Any ideas? Should I stop being cheap and swap in a new alternator and see what happens?

 

Have you checked battery terminals really good and cleaned them? Check the battery cables themselves for corrosion. Wiggle them and see if it affects anything. I've seen the cables corrode about 12inches from the battery but inside the plastic sheathing.

 

I had a similar issue with my old 4 runner. It was a short in a wiring harness. Maybe try to mess with it in the dark wiggling wires around looking for a spark. That’s how I found mine. Good luck

 

Full disclosure* The new brushes I recently installed were OEM, however, the voltage regulator was non oem from EBay. I am thinking it was a junk part. My first thought is alternator, although there is no battery light.

 

Where you able to figure out problem? Im currently having this issue

 

Old thread!!

If your engine is shutting off with a added electrical load it might be the system voltage is dropping to low.

Time to break out the Multi meter and get real world numbers.