Question on dash lights for charging issue (1 Viewer)

[ColoradoCarlisle]

Just bought a HDJ81 from Oregon and the PO put 2 bran new correct batteries in the truck

Then shortly after was getting dash lights on indicating the alternator needed replacing

I installed a New 140 Amp alternator and now the lights stay on for a couple minutes after I start the truck then all of them at the same time disappear

Any Ideas

 

[roscoFJ73]

The first thing I would do is check the earth strap at the engine end or chassis end. And the voltage at the alternator

 

[ColoradoCarlisle]

Ok thanks
I’m wondering if the batteries wet not charged enough as today they are all going off after about 20 seconds where as right after I put in the alternator it was taking about 5 minutes

 

[roscoFJ73]

Thats possible, go for a long drive or put them on a charger. A charger would be best.
But usually the first symptom of a partially charged battery would be a failure to start.

 

[ColoradoCarlisle]

Thanks for the help!

 

[B1PowerWagon]

I JUST solved this exact issue on my 1990 HDJ81. It's the voltage regulator. If you still have the original alternator laying around, swap the original regulator into the new alternator. If you don't have the original alternator, buy a Toyota Regulator P/N 27700-16010 and swap it into the alternator. I found one on e-Bay for ~$19 USD.

For whatever reason, the regulator on the HO alternator doesn't play well with the HDJ81. Now when I start it, the lights are out.