3 days ago my monty died it was the alternator that was bad now i bought a aftermarket one and my battery and brake light still come on.

my battery with the truck off is 12.7v but alternator when i start the engine is 14+v but after 10 minutes battery and brake lights come on again. i took the alternator to be check and it passed, before putting the alt back on the truck i cleaned all connectors on battery, alt and starter but still the same issue btw i checked the main fuse plus the rest and they are good.

my truck starts good and runs good doesnt stall or anything like that no dim light either and some times the battery and brake light come off by themselves.

i have tried looking it up and ive tried everything ive found just wanna now if somebody here has had the same issue here that could share a possible solution

 

Do you get 14 v. at the battery when the engine is running or just at the alternator?

 

When i leave the engine off over night in tge morning with tge engine on i get 14+ but after a while the battery and brake light will come on sometimes while driving they come off but then go on again i dont have any lost in power my system behaves normal btw when the lights come on my voltages go down to 12v when engine is on

 

that's two separate issues.

1) reset any "computer ****" - disconnect battery overnight.

2) flush/bleed the brake system

if it still happens:

3) assuming both lights come on together, find a manual and find out what is the computer is trying to tell you.

 

Sounds like voltage regulator issues, but I'm not 100% certain.

 

[QUOTE=HunterD;307604]Sounds like voltage regulator issues, but I'm not 100% certain.[/QUOTE

I think i have a loose ground or something cuz sometimes the warning come off by itself the i can take awhile to come on again

 

That could be it too. Double check all your grounds. Disconnect them, clean and reconnect. Check the engine grounds and the main ground connection for any corrosion or oil.

 

I turn out to be the voltage regulator

The alternator used to fail after the engine warm up maybe longer than that but in the test they do the test it for less than a minutes meaning that it is always gonna be good for them they didnt wanna give another one but at the end they did and now everything is ok

 

It always feels good to figure out after lots of troubleshooting what is not working. It's like a weight off the shoulders. Happy miles bro.

 

I had this same thing happen today while wife was driving it. 2002 Montero Sport 3.5 XLS

She said brake light came on, battery light came on also. Then SRS light came on and another that she could not remember. She said engine would not rev over 3000 rpm and would not shift gears. Radio quit working, then came on, off etc. Said many dash lights were flickering (SRS, Anti-Lock). She limped home.

Vehicle has just had a complete engine rebuild by me. Runs nice. All battery terminals cleaned.

Prior to safety inspection, the dash lights would not work (car was outside) but radio and radio light would work and dim with the dimmer. Cleaned the small engine ground up by the EGR solenoid and the dash lights were restored. I had painted the plenum and I think that was it. The dash lights in bright sun are not bright. Only till I put the vehicle in the garage with the garage lights all off and door closed could I see the dash lights so It is possible they were working all along.

I did just replace the battery 5 days ago. Safety inspection shop said they thought the battery and alternator were bad 5 days ago when I had it inspected. When I picked it up, would not start, so I bought a replacement battery (it was over 3 years old and vehicle had been dead for 2 years).

I tried just now to start it up, it started but starter spun a little slower than usual. Runs ok slight rough idle (separately chasing a P0403/P0306). Checked battery voltage while running with no loads and got 8-10 volts. No change when reving the engine. Radio works, all lights work. Battery light is on, no brake light now.

Turned engine off, disconnected the battery negative, battery positive, and cleaned all leads. Checked alternator cables and all tight. The 100a fuse at the engine fuse box has continuity from the stud to the battery post thru the cables. Restarted engine, and the brake and battery lights are flickering. Then the SRS and Anti-lock lights came on solid, then the brake and battery lights went off. Turning the headlights on and off results in the Tach jumping 500-1000 rpm yet no discernible change in real rpm.

I think alternator and/or regulator died. I understand the regulator is integral with the alternator?

The alternator is OEM to my recollection at 173k miles. It had some oil on it when I rebuilt it, but not obscene. I understand leaking front cam seals can kill the alternator with leaking oil. My front cam seals did not leak, but then there was prior head work and maybe the original seal leaked and killed the alternator over time.

Thoughts?

Recommendations on replacement alternator and/or which ones to avoid? NAPA ones ok?

I want to fix it this weekend.