L16 charging problem

[ka620']

Whatsup guys i have a question that im hooing one of the gurus can help with. So mt 620 started shorting out causing the fuse that runs the alt to pop. I took out the after market radio (so many wires were touching the body it was pretty scary...anyway..) so after getting rid of the wires and fixing the short I just went ahead and got a new battery. After installing and starting it up i pulled the ground strap to see if it would run off the alt. It idles just fine but as soon as i try to rev her up she just chokes up and misfires. I hooked the ground strap back up and revved it up , she revved up perfectly not a single stutter. So I'm just stumped... Am i looking at a failing alt? Bad grounds ? Thank you for any input in advance!

[datzenmike]

It revs up just fine.... I'm not seeing a problem here. Sounds fine to me.

 

BTW the battery should never be disconnected from the vehicle when it's running. The battery smooths out the voltage. Revving it up may cause a higher voltage surge.  A quick disconnect while idling may be ok.

[Draker]

It's a common test to verify the alt. But yeah, not to be ran that way for long periods of time. Its even mentioned in ASE auto classes.

 

I'd just run it as it is. If you are seeing 13-14v while running.. it's fine.

[ka620']

Hey guys thanks for the replies , so after fixing my multi meter i fired up the 620 let it warm up and tested the voltage. I was getting about 16.5 at idle and just north of 17 at 1/4 throttle.. any ideas on what causes an alternator to overcharge the battery?

[datzenmike]

Either the alternator or the voltage regulator is faulty or perhaps wired wrongly. I wouldn't run it like this as it will shorten the life of the battery.

 

Some back story, please.

 

Has the alternator or the voltage regulator been replaced recently? 

Does the wiring on the alternator look like some one has spliced it? Replaced wiring?

Has this run properly and just started acting up?

[Rick-rat]

Most likely the voltage regulator, if it has an external regulator

[ka620']

Yeah the voltage regulator pigtail comin out of the harness only has 2/5 wires connected. 3 diked wires.. regulator looks to have been replaced already. Is there anywhere i can get a schematic ? Well im sure it was slowly killing my battery but i never noticed anything until i started getting popped fuses because of the aftermarket stereo and exposed wires , anyway previous owner tapped into the fuse block for that after market radio and it was on the same block as the alternator. So when it shorted , the fuse popped ,and the gauges went.. i didnt think much of it but little did i know my alternator circuit wasnt complete anymore. So i drove it around and completely drained the battery out before i relaized it was all connected. So i took out the stero and excess wires and the shorts stopped. I just got the new battery and here we are today..

[datzenmike]

I suppose the alternator could have been replaced with an internally regulated one. That requires some of the regulator wires to be cut and connected together but usually the regulator is then removed as it isn't needed.

 

Try this for a wiring diagram... http://www.davidcmurphy.com/olddat/620tech.htm

[ka620']

is there any way for me to tell if its an internally regulated alt ?

[datzenmike]

I believe your external regulated alternator should have an N and an F mark beside the two wire plastic plug in the back. An externally regulated alternator will have L and S.

[banzai510(hainz)]

take some photos

 

over volt is usually a bad volt reg external or internal.

 

But why wires cut?  any jumpered?

[ka620']

awesome , thank you mike your the man. its an external regulated alt. I'm going to re wire voltage regulator according to schematic and see where that leaves me. Ill let you and the forum know how it goes.

[ka620']

banzai , not sure why wires were cut , this truck is full of hacked up wiring. I figure ill just slowly but surly fix it all. The only wires that are hooked up to the harness side of the regulator pigtail is black(ground) and white.

[datzenmike]

NO!!!!

 

Two pairs of wires on the voltage regulator need to be cut and joined to make the switch to an internally regulated alternator. Unplug and remove the external regulator. Trim the wires off the old regulator but leave them long. Join the WHITE and the YELLOW wires. Join the WHITE/YELLOW (stripe) and the WHITE/RED (stripe) wires. Twist them together and solder or any good firm electrical connection and use shrink wrap tubing to insulate them. Remove any other wires from the regulator plug. Plug the modified regulator plug with the joined wires into the harness.

 

 

Because of how the automatic choke works the relay for it is now (unfortunately) permanently wired ON at all times and will drain the battery over a weekend with the engine off. No worries, it's an easy fix. Unplug the auto choke heater relay and /or remove it. Choke now has no power for it, so..... Look on the carb for the RED (idle cut solenoid wire) and the BLUE (choke heater wire). Connect the the BLUE choke wire to the RED idle cut wire. The choke now gets it's power from the idle cut solenoid which is turned on/off with the ignition.

 

 

Done... and it was so easy. Now you can add an even higher amperage internally regulated alternator.

[ka620']

yeah , thats how it was wired. i guess it had an internally regulated alt on it before it was in my possession, and when it failed on me i got a new alt and voltage reg thinking it was externally regulated because the regulator was still in the bay. since i already have the new alt and voltage reg installed im just going to wire it back up for the stock externally regulated alt. I understand its better to run an internally regulated one but I'm swapping a ka in soon so I don't want to go out of my way for this motor.. and man my choke has ALWAYS been stuck on and I couldn't figure it out for the life of me. now I know what it was , I'm assuming going back to stock wiring will get rid of that ? thank you.

[ka620']

So after re wiring to stock i noticed there were resisters inbetween two sets of wires, were these resisters put there to excite the alternator ? After re wiring back to stock the alternator stopped kicking. My only conclusion is that it doesnt have an exciter now. Is that what the charge light is for on the dash ? Or is that for a low battery ?

[ka620']

Took my dash out to see if the charge light was an exciter like i thought. Got a good bulb in there now and now the light stays on. So im guessing that light comes on when the alternator isnt charging..

[datzenmike]

Who can say what someone else did? I only know about the stock set up. There shouldn't be any 'resisters' in the charge circuit. The red charge lamp must be in working condition. Turn key on it should light. Start engine, it should go out if charging.

[ka620']

Ok so these alternators dont need an exciter to get going ? Ive rewired back to stock but the alternator just isnt coming online now

[ka620']

Do we know what wires we should be getting voltage to ?

[datzenmike]

Ok so these alternators dont need an exciter to get going ?

 

It's excited by the charge light. That's why I said it must be working. 

 

 

You've already said the wiring is hacked. It could be anything even the 'new' alternator. They've been known to be 'bad in the box'.

[ka620']

Forsure , my charge light is real inconsistent. Wether its my cluster or a connection inbetween im not sure , but do you know where the power is coming from so i can make my own charge light to see if i can get the alt going ?

[datzenmike]

Turn ignition key on. Does lamp light? Yes... it's working.

 

One side of the charge light goes to the battery (through the ignition switch). The other goes to the L terminal of the plastic plug on the alternator. If not turning the L terminal is grounding the lamp turning it on. When charging there is 14 volts on the L terminal and with power on both sides of the lamp it won't light up.

[ka620']

So ive fixed the connection on my cluster and my charge light is consistent now. But now my charge light just stays on. Does this mean my alt has failed ? Im only seeing 12 volts at L terminal and its only one of the wires that gets voltage.

[datzenmike]

Turn key on red light should light up. This is the test for the driver to show that the bulb is good.

 

Start engine, light should go out if the alternator is charging. 12-12.6 is battery. A charging alternator is usually just over 14 volts.

 

 

 

As this has been converted from external to internal regulated alternator and then back to external I would look at the wiring. Ground wire (Black) on alternator case? Two wire plastic plug is snug and gripping the terminals? Larger White/Red charge or power wire is connected to the insulated terminal on the case?

 

Next have the alternator and regulator checked. Usually NAPA can do this.

 

If you have the original external regulator maybe it's bad and why the last owner converted it to internal regulated alternator?