Hey guys i've been having some problems, about a week ago my brake and battery light came on. every once in a while, if i hit some bumps the lights will flicker, and if i make them flicker long enough, they will go out. now i put a meter on battery and it read about 12v with the car off, then started it and it didnt move(so the alternator isnt charging the battery, while the brake and battery light are on.) Also the volt gauge on my truck the pin is right about in the middle while the brake and battery light are on, but when i get the lights to go out, the pin goes up towards the 18 mark more(like the alternator charges the battery when the 2 lights go out, but when there on it doesnt charge. heres a pic of my gauge with the 2 lights off and whn there on the pin is in the middle, so is this a short thats stopping the alt from working or is it the alt? sorry if this is confusing, its kinda hard to explain and it definitly is making me confused. thanks

 

have you checked the batt cables? Are the connections clean and tight? How 'bout running from the batt to the alt? The connections on the back of the alt tight as well?

 

ya the connections seem good and tight, along with the ground wires that i could find, also tested the wire from the battery to the alt and it was feeding 12v to the alt.

 

something inside the alt could be loose, or the alt is on it's way out. Sorry, I'm not much of a guru on wiring and such. Maybe start your rig, have some1 sit inside, and have them watch for the lights to come on, as you start to wiggle some wires around....

 

yea ill try that, i was going to take the alt off and have it tested, but didint want to go through that work if its not the alt. im not good on electrical either... i feel stupid

 

lol, no need to feel stupid, bro. There are lots of us who don't understand wiring....lol. Personally. I can understand stereo instructions, written in Gailic a lot easier than wiring.....LOL. It's all good bro. Some people are good with stuff like that, and some of us aren't.....

 

Sounds like you have loose wiring.

 

or the regulator in the alt is out

 

My truck did that and after changing the alt made no difference I tested the wiring. Turns out I had corosion in the fuse box causing the fuse to pop. Cleaned it out sealed it up all is good.

 

my fuses are good, where should i look for corrosion? also should i have the alt tested to eliminate that first?

 

i guess ill just take the alt off and have it tested, ill let you guys know the outcome. thanks

 

If you are only measuring 12V at the battery with the engine running, then something is going on with the alternator. I would have it tested and go from there. That is a likely culprit given the low voltage at the alternator.

 

Mine did the same thing today, battery & brake light came on. Don't know if the lights went off as it was day time. Kinda worrisome cause I'm starting a 2 week road trip thursday... I have a new alt that I haven't had time to install and was going to bring it with...

 

If you have a charge light relay, check that it is operating properly; there is a diode circuit involved. The brake light / charge light are tied into charge light relay circuit. Get a wiring diagram from your Toyota dealer, they usually will make you a copy from a
service manual for your truck. Check the circuit of the voltage regulator that ties into the Charge Light Relay.

 

I would look at the harness near the rear axel,passenger side for a wire that has rubbed thru.There is a plastic sleeve there, and the wire takes a turn and is exposed close to the frame.Mine did the same and thats where I found the problem.