New replacement alternator not charging starter battery-SOLVED…….almost……Now its Workin!

1994 3.0 VZE engine. I am currently on vacation at the beach in N.C.
Here goes;
I have two year old Odyssey battery as a starter battery. Drove across NC to the outer banks with out a problem. Yesterday i noticed that my battery voltage was 11.8, and that the alternator was not charging the battery. (Measured with volt meter at the battery terminals) just installed a new rebuilt alternator from NAPA . (Had it sent over on the ferry to Ocracoke Island. This morning)
I installed the new alternator. Checked all fuses. All were good. I again checked the alternator voltage at the battery. After starting car up.Still not charging and the battery voltage is 11.6.
Car still cranks over. But new alternator is still not charging battery.
I have ordered a new starter battery to be delivered tomorrow.
Am I missing something ? Is there a minimum battery voltage to get the ECU to recognize, to get the alternator to charge the battery?
As I said all fuses were good and intact, in the engine compartment. And along the left driver side wall.
– Dumb dash warning lights show, dim battery and parking break warning lights somewhat flashing dimly.
Any assistance would be appreciated ….ideas and thoughts?
Thanks

 

Battery is not the issue. Even a bad battery will show the higher voltage across the terminals.

I assume the voltage regulator is internal to the alternator? Do you know?

The alternator's sense wire needs to be connected to the battery to let it know it needs a charge. This is a separate connection than the charge wire.

There was probably nothing wrong with your original alternator. You probably have a broken sense wire from the alternator to your battery.

There may be an ignition wire that needs 12v to the alternator as well.

Do you have the Factory Service Manual? It will show you all fuses in the path of the sense wire.

Here is a great video...even for a 2010 it's very pertinent:
https://www.youtube.com/watch?v=K7EBcdQsfZA

-Mike

 

Thank you for this video link.
I will closely inspect the wiring harness and fuses tomorrow morning.
This engine has been removed TWICE…for exhaust vale repairs, cross over pipe delete, EGR removal. So plenty of opportunity to rub a wire bare, weaken wires on the plug harness, etc.
I have a multimeter with me. After viewing the above video link, i can see how one small nick or bare /loose wire can create this problem.
I will post my findings after inspection.

 

Ok, latest findings;
The voltage regulator is internal to the alternator . Mounted on the back.
I tested the 3 pin Toyota alternator harness.
Juggled it, pulled in it to make sure the wires were intact. With the multi meter; I was getting ;
Alternator signal pin; 11.8 volts (also used jumper wire back to the POS battery terminal to test continuity. Checked out ok.
Ignition power pin; no power with key off. With key in on position, 11.6 volts. I believe this is normal operation.
Alternator charge warning light pin;
No power with key in off position, with key in on position 11.4 volts detected.
Again checked all fuses , all were good. Under hood fuse box as well as the driver side down by left foot fuse box.
Awaiting the new starter battery to arrive sometime today on the ferry. (Maybe as slate as tomorrow)
Thinking…… has the old starter battery dropped below the minimum voltage that is needed to tell the ignition pin to turn on the alternator regulator?
Or…am I completely wrong about that thought process?
All positive and constructive comments welcome…..

 

In my experience if the battery is strong enough to start the vehicle, there is enough excitation voltage for the alternator to work. If the battery is completely flat and you use jumper cables and remove the cables too soon the alternator my not have enough voltage to work.

When you installed the replacement alternator did you check for voltage at the alternator when the engine was running? If you have around 13.5v at the alternator and 11v at the battery there is a bad wire or corroded terminals in the system.

 

My initial check just after installing the alternator showed: No charging at the battery and no charging at the alternator output bolt.
( it may have been a poorly excited test)
I will check for charging directly at the alternator again.. test clip on the nut on the alternator where the output wire bolts on and the other test clip on the negative battery post.

 

Well, here is or was the solution…
Posted on the yota forum back in 2019. (From an original 2014 thread)
This issue has appeared before……
Apparently even though all the fuses look ok,
The fuse box to the left of the drivers foot (this is the location of the 7.5 amp ignition fuse) may have a loose connection behind it. (there is a large wire harness that clips into the back of the fuse box. The poster stated that he loosened the fuse box from the wall.. visually checked the connector on the back… gave it a bit of a push the best he could (crappy location) and then retighten the fuse box to the side wall. Problem solved….
So…..being on Vacation at the beach with time to kill, reluctantly wanting to get into “messing with the fuse box”…. That’s what I did…loosened it up, gazed At the connector on the back,, gave the whole thing a push against the wall and …. Tightened it back to the side wall.. fired up the engine… alternator is charging! Problem solved.
Who knows,, these are 28 year old trucks.
That’s why these forums are so valuable.
Thanks to all who responded or just read the thread. I will only post further if the problem resurfaces.

 

I was one of the readers of your thread, and am glad to see you found a fix. You might want to edit the title:

New replacement alternator not charging starter battery - solved

 

Done

 

Kudos for patience and thanks for the review and reminder

 

Not so fast folks…..the electrical gremlin resurfaced today.
I will be completely pulling out the left driver side fuse box tomorrow AM while its cool outside. I did find a replacement fuse box on ebay. So i was able to get good photos of what it looks like removed.
I will update as i progress………l

 

Searching other old YOTA forums, suggest checking and cleaning the ground points around the engine bay. battery terminals, 80 amp fuse link wires (located in the engine bay)
There are several ground points on the 3.0vze;
Right passenger fender.
Rear of plenum to the firewall
Alternator ground to engine block (around cylinder 4 )
Around where the A/C mounting bracket is bolted
Driver side from the coil area to fender

Also it was suggested to check the POS wire terminal from the battery to the fuse box, the factory crimp on the wire connector could be loose and or corroded.

Oh, and did I mention I was at the beach driving on the sand near the ocean? Everything worked fine for the first couple days. Than the electrical gremlin appeared. And of course I have an oil leak, somewhere on the driver side dripping down…Hummmm….lots to do.

 

Just as a side note; while I was headed to the island hardware store on Ocracoke,(by bicycle) I saw this really sweet restored early 90s Toyota Land Cruiser completely redone, right hand drive, Diesel engine just Ticking along…….. I had to stop and turn my head to look…… It was then that i realized… There is no way I will sell this 1994 3.0 VZE Manual 5 speed, 254,000 miles, one owner super sweet 4Runner!!

 

Meanwhile…..6 hours later… Please remember, I am not at home. I am at a rental cottage on Ocracoke Island,NC. Only accessible by ferry.
Up and started on this project at 6 am under the cover of the high deck on the cottage.. local islanders loaned me a battery charger and space to work on the truck for the alternator install several days ago.
I chose to do this project at the rental cottage due to high heat and humidity and the length of time required. ( unknown at the start, but eventually took 6 hours from start to finish. Frequent breaks included)
Knowing that the truck is 28 years old and that i am and have been in a marine/ beach environment…..I choose to clean all the negative grounding points that i could access in the engine bay of the truck.
And after reading several posts on various forums..I opened up the main under hood fuse box and cleaned the 80amp slow blow alternator fuse wires and contacts. I also cleaned the oxidation and crud off any POS alternator connections.
Here are some before cleaning shots and some after shots showing cleaner and more secure connections, I did not take photos of everything ;


So, it was hot, sweaty, tedious. Took 6 hours. And I didn’t know if this would solve the problem of the alternator not charging the battery……….

 

Well………..It Worked! Cleaning as many grounding points and removing the oxidation on electrical contact points must have lowered the electrical resistance in the system.
I am getting 14.1 direct at the alternator and 13.9 at the battery.
on engine idle.
Modifications to make once I get the truck back home:
Upgrade the main battery NEG ground at the right fender to 4 or 6 gauge wire with new terminals.
Upgrade the POS battery wire entering into the 80amp slow blow fuse at the engine compartment fuse box with 6 gauge wire and new connectors .
Upgrade to a larger output alternator, 60amp just doesn’t cut it with extra lights and a winch.
Final thoughts:
When trouble shooting problems that arise ….Think of the simple stuff FIRST.
I didn’t need the new alternator.
I didn’t need to cut into the alternator wiring harness with a new plug.(considered it)
Carry a multimeter to trouble shoot.
Carry tools to fix stuff. ( I have way to many with me)
Utilize local people, they really do want to help.
Keep a positive attitude ….
And Don’t get GRUMPY!!! ( my wife says that i need to work on that one .)

 

Good job. You may wish to preserve those ground points since they are now bare metal so they don't start rusting.

 

I had thought of that as I was getting down to bare metal. What would you use to preserve them? A clear lacquer? Or a dab or two of touch up paint in the appropriate spots?

 

I’ve always used undercoating for this type of touch-up. Cut a hole in a cardboard box panel to spray through (where appropriate) so I’m not taping off all day.

 

Boeshield T-9 or ACF-50 are my first choices. Spray on battery terminal protectant also works well.

 

I will try some T-9. I can get it quickly on Amazon delivery. Thanks!