Strange electrical/charging/starting??

[niggz]

The more I think about this, the more confused I become.

I have an 85 BJ60 (12V)

I had to jump my truck today, and it immidiately started showing signs of a fried alternator or IC regulator maybe. The volt gauge was in the red and cotinuosly dropped on my way home, all my lights getting dimmer and dimmer.

It won't jump now even from my dad's bj70, which is another two batteries. Relays everywhere just click and click.

Can a fried alternator stop my truck from starting? It's all really strange as the gauge in the truck shows no voltage, but the batteries each measure a fairly healthy 11.99V and 11.90V. I thought maybe it is the IC regulator, but I switched it with my dad's from his bj70 and still no luck.

The PO had a new toyota alternator installed a couple years ago so I really can't see it being that. It doesn't make sense to be the alternator because it won't even jump start.

This leads me to believe it might be the starter, becuase a couple times it tried very labourously to turn over, but that wouldn't explain the dimming lights on the way home.

Maybe I am way overthinking this. The only thing I can think of is something is drawing a huge amount of power. Or the IC and the starter both died at the same time.

FWIW I also just installed a manual glow relay setup yesterday, but I am very sure this is not the source of the problem. Too be double sure, I disconnected the relay from the battery and still nothing.

Any ideas?

 

[roscoFJ73]

If you dont have the means to test the alt yourself,remove it and have it tested.

I would also check the earth lead and the wiring to the starter.
A lot of people blame alternators and starters when the problem is resistance from bad contacts which means the battery cant recharge and the starter doesnt get enough for cranking speed.

 

[MrMoMo]

Have you measured the voltage at the alternator B post? 11.9V is pretty low, but your volt meter should be reading the same as your batteries, sounds like you have a bad connection somewhere. (voltage drop before your meter). As stated previously, check your grounds. If your engine block ground has come off, the starter could have a very hard time rolling over. When your relays click - do they click on/off or chatter on/off/on/off/on/off/on/off really fast (flutter) Relays chattering or fluttering is a sign of low voltage, which if you for sure have good batteries, is likely due to a bad connection.

 

[niggz]

I've found out batteries at 12v or under are pretty much dead so I got new ones. I also cleaned off the grounds. Haven't put the new bats in yet, I'll check the b post tomorrow when I do.