Toyota Tundra Discussion Forum banner
1 - 20 of 23 Posts

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #1 ·
So i was on my way to work today and the voltage gauge started bouncing between 12 and 14 volts..real fast. I decided to load the battery a little more, so I hit the window switch up. All the gauges go to zero and lights on the dash light up, just briefly. I let off the window switch and the gauge goes back to jumping to between 12 and 14 volts. I tried the same thing with the headlights and got the same result.

I got to work and my hot cable was a tad loose, so i tightened it up. The ground also has a little corrosion on it but not much.

On my way home after about 15 miles it started acting up again. The window switch or lights didnt make the gauges die, but the voltage gauge was jumping. When i got home i heard a squeeling from the front, definitely belt related.

So my question is. Alternator? Battery? Or short somewhere? 150,000 miles on the truck. 5.7 battery is only 1 year old.

I do all my own maintenance and am pretty good with my hands...have done ujoints and rear diff. I figure alternator shouldnt be too bad if that is indeed the problem. Sucks our alternator is on the underside though.

Thanks!

Sent from AutoGuide.com App
 

·
Registered
Joined
·
1,172 Posts
Check all you cables - clean everything both end of ground cable - dirt under connections can cause alot of problems. Have batt and ALt tested after cleaning cables
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #5 ·
So i havent had a problem since I posted, until today.

I'm on my ride home and the gauge starts jumping again. My radar detector starts beeping on and off "low voltage". Then the motor dies, restarts right away, and no problems at all with the voltage.

I get home, turn off truck and restart and have the same problem with my voltage gauge again. I turn on the headlights to draw more power, and the truck dies. Dead as anything. No power, no lights, nothing. I keep trying to start the truck, but no power at all. still no lights. After about 2 mins the lights all turn back on and the truck starts no problem, voltage gauge perfect.

Any ideas? Short somewhere?
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #8 ·
Problem has resurfaced...except its the other way now.

Jumping between 14 and 16 volts. Shut the truck off and restarted and its a steady 14.

Any ideas? Alternator only has 30k on it, could it be the voltage regulator in the alternator?

I have a video, ill upload to youtube and post here.

Thanks
Austin
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #10 ·
Problem has resurfaced...except its the other way now.

Jumping between 14 and 16 volts. Shut the truck off and restarted and its a steady 14.

Any ideas? Alternator only has 30k on it, could it be the voltage regulator in the alternator?

I have a video, ill upload to youtube and post here.

Thanks
Austin
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #11 ·
Have you done as recommended above? check all the grounds.
Yep I have tried all of the above. Cleaned both terminals really good and checked all grounds.
 

·
Registered
Joined
·
1,053 Posts
in three months you havent taken it somewhere to at least check alternator and battery? man you should do that it takes only a couple minutes out front a pepboys or something similar. they can put a load on it and check both the battery and alternator, alternators can go bad in 1 mile, so 30k would be surprising.
 

·
Registered
Joined
·
1,707 Posts
Check belt tension? Within limits?
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #14 ·
in three months you havent taken it somewhere to at least check alternator and battery? man you should do that it takes only a couple minutes out front a pepboys or something similar. they can put a load on it and check both the battery and alternator, alternators can go bad in 1 mile, so 30k would be surprising.
No I replaced the alternator 30k ago because it went bad. This problem just started yesterday on my way to work. And dont you have to remove the alternator to get it load tested? Removal is a few hour job on these trucks.

And I did not check belt tension, I will check that today.
 

·
Registered
Joined
·
399 Posts
With the engine at normal temp, idling; check at the battery with a multimeter and see the reading.. It might be the gauge..

Normal readings are around 13.5~14.2 volts..
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #16 ·
With the engine at normal temp, idling; check at the battery with a multimeter and see the reading.. It might be the gauge..

Normal readings are around 13.5~14.2 volts..
I have a secondary voltage gauge that I installed via the fuse box. That one was jumping too, up to 16 at times.

Its an intermittant problem, goes away after turning the truck off/on
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #18 ·
did you ever figure out the problem? I just spend 4 hours replacing my alternator and the gauge is still bouncing!
Bad connection on the positive terminal.

I took off the terminal, replaced it, and put some battery spray on it and its good.

Alternator is a PiTA isnt it? Haha been there done that.
 

·
Premium Member
Joined
·
1,477 Posts
Discussion Starter · #20 ·
1 - 20 of 23 Posts
Top