4g Alternator Charging Issue - Fixed!!!

[Izzy]

And the fight continues. For this round, I am battling a charging issue.

A couple of weeks ago, the bronco died on a short trip to the depot. Had to tow it home for the first time ever

I was pretty confident it was the alternator so I pulled it and took it to Autozone to test and replace. Tested bad so got a replacement (thank you lifetime warranties).

Put the new one in and while everything is running, I'm only reading 11 volts at the battery when the engine is running. Shouldn't it read 13.6-13.8?

Where do I begin to troubleshoot this latest issue?

Engine is a 5.0 with Explorer serp and 4g alt.

Appreciate the help

 

[Joker11]

Did you have them test the new one before you left the store? I have found that some products are bad right from the store.
Just that margin of fail rates nowadays.
But if nothing else changed, that would be my first option, testing it.
Now, if this was a new conversion to a 4G, I would suggest tracing your wires and make sure you have voltage where you should. Voltage to excite the alternator, good grounds and such.

 

[Izzy]

It is not a new install, has been done afor about 2 years now.

I did recently change out my dash so I "touched" my ignition switch but I checked it last night and all the wires were secured.

 

[DirtDonk]

Got a pic of your alternator at the connectors? Stock wiring harness? What color wires are where?
Basically you need to check your excite wire, like Joker was saying, to make sure it's got 12v with the key in the RUN position.

And the sensing wire (usually Yellow) needs to have a good signal too. Most are simply attached to the main power output stud on the alternator, but it all depends on how you wired it.

Totally agree that new parts can be bad. And it's not just on rare occasions anymore. It's a VERY high percentage compared to the "old days" it feels like.

Good luck. And yes, mid-13's are probably acceptable, but at the lower range. Expect to see 14.5 if all the components are playing nice together.

Did you install a Mega-Fuse in your new charge wire? Did you verify that it's not blown?

Paul

 

[ransil]

make sure the alternator case is grounded , it grounds via the mounting bolt to the motor.
Make sure the mounting surface is clean. ( no paint, powder coating corrosion ect)

 

[Joker11]

Talk about failure rates...
A little off topic, but at work, I replace parts that cost 80 Grand a piece. Half the time we have stuff failing 3 times out of 5 on a re-manufactured part. The level of quality control is out the window. It makes everyone look bad. Our customers dont care about our supply issues.

 

[Izzy]

Thank you Paul for the clarification.

The harness is a painless harness and the RJM EFI Harness. The wires on the alt are the green and red one and the yellow one.

The black one you see is going to the mega fuse and then the battery (positive side). How do you confirm the mega fuse is not blown? I did check voltage at the post where the bloack wire is connected and then at the 1st terminal of the mega fuse, then the second terminal and then the battery and all 4 points read 11 volts.

I did confirm the alt casing has a solid ground as well.

 

[Izzy]

Here is a pic

 

[Izzy]

Ransil, as you can see in the pic, I have a ground wire going direct to the alt case via one of the mounting bolts

 

[KyleQ]

That ground is overkill, but it won't hurt anything. There is ONE wire that turns it on or off via ~12v (I've actually got mine hooked to the starter relay key-on post and I tihnk it's just over 6v) - so check that wire. If it doesn't give power to the regulator to turn on the alternator, it won't do anything...

 

[garberz]

That ground is overkill, but it won't hurt anything. There is ONE wire that turns it on or off via ~12v (I've actually got mine hooked to the starter relay key-on post and I tihnk it's just over 6v) - so check that wire. If it doesn't give power to the regulator to turn on the alternator, it won't do anything...

This^. The green/red wire on the Alt. pigtail, comes from the key switch. Check that you have power there with the key on, engine off.

Mark

 

[pcf_mark]

Once you chase your wiring and have power on the green / red check the belt. I had what I thought was a bad alt and Dirt Donk suggested that and magically I had juice and have for about 2 years!

 

[Joker11]

Don't you love it when it is an easy fix like that? Way to go Paul.

 

[DirtDonk]

Wish they were all that easy!

... How do you confirm the mega fuse is not blown? I did check voltage at the post where the black wire is connected and then at the 1st terminal of the mega fuse, then the second terminal and then the battery and all 4 points read 11 volts.

If the alternator was charging things, you'd have at least seen the higher voltage on one side of that fuse I think. But now that I'm "overthinking" it, I'm not so sure! %)

Sure way to verify one is still intact would be to test it with an ohm-meter. I don't know if Megas always show external damage from being blown or not. But an ohm meter (with the fuse out of the holder) should tell the tale.

The fact that all the voltages you tested are the same would seem to indicate that the fuse is good. But I'm in favor of taking that extra time to pull it and verify.

Paul

 

[KyleQ]

No need for a fuse - they are amp rated, it won't stop 16+v from killing everything hooked up to it...

 

[Izzy]

Ok, found my issue. I found that I had a blown fuse in the EFI harness and as soon as I turned the key to on, it would blow again. Traced it back to a loose wire I had that was grounding out and blowing the fuse. Removed that wire and everything works now.

It's the little things. Guess it's time to clean up some wiring.

 

[NDJoeBronco]

Alternator not charging Explorer swap

Fast Forward September 2019 alternator does not seem to be charging.. Replaced with new and the voltage is still 11.7 (battery voltage) little about the truck garage built, Explorer Swap, EFI guy harness, & AAW harness only main wire (fuseable link) from Alt is going to solenoid Battery+ side. pigtail yellow/white wire is also looped back directly to the alternator post?? Good Grounds throughout truck. checked EFI guys fuse block all are good?

 

[bronkenn]

Wondering if you gave it a little throttle to excite the alternator? Mine will be low output until I blip the throttle.

 

[DirtDonk]

Is there a more detailed discussion on your build showing how you have it all connected NDJoe? How is all this integrated together? Got a pic of the alternator area and wiring?

You replaced an old Explorer alt with a new one? Neither worked?
Are you getting a 12v signal on the Green w/red wire at the alternator's connector when the key is ON (but not in ACC)?
When you measure voltage directly at the output post of the alternator, are you seeing anything more than that 11.7v?

Paul