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Discussion Starter #1
Had a concerning question about my 1998 Dodge Ram 3500 12 valve 5.9 turbo diesel 4x4 manual.

My alternator wasn't working. I tested the battery and it was 11.75v then started the truck and it was still 11.5v. (note battery was low because i got done driving). So I took off the alternator and went to a local auto store and got it tested and resulted as "good" scoring at 15.37 volts.

Dropped it back in, still same scores when engine is off or on. So figured it was the computer. It cost too much well over $300 bucks and these days, we all know money isn't easy to get. So i was recommended to do a exterior voltage regulator from 80's Chrysler. I have never done that before so the guy at the auto store told me how to do it and it seemed simple. He said to connect 1 wire from one of the 2 smaller alternator studs to the regulator and another (hot wire on ignition) to the regulator..... well after blowing like 25 fuses i figured out that he didn't give a good explanation by forgetting to tell me i need to run and split one of the grounds from the 2nd smaller stud on the alternator to the hot wire going into the regulator.

Anyways so my voltage regulator started to work, it scored around 16-17 volts and i figured the battery's was dead and the alternator was charging it by giving a lot of juice. Well i took it on a 40 minute drive, came home and smelled something funny and stinky. I open the hood and saw my MAIN BATTERY smoking and acid inside was cooking... The battery plastic was nice and soft :eek: . I took my volt meter and tested it real quick to see what Ive been running my truck on and it tested 16-17 volts!! :eek::eek:

So i figured i fried my volt regulator(when connecting it and blowing 20 some fuses) so i went and got a brand new one again. Only $8 bucks at cost less auto. After 5 hours or so when everything was nice and cool, i fired the bad boy up. The voltage i am getting right now is around 15 to 15.10 . When i turn my headlights on and radio real loud i am getting around 15.12 to 15.18. I notice my positive cable is tight to the battery which it doesn't move around but could be in better overall shape.

The question is. 15.10 volts ok for dual battery dodge? How come my other battery didn't cook instead just the main one? It was getting the same voltage. The main battery has a worse shape positive cable but does it play a roll in the voltage game? When the truck is on, both 15.10 volts on the cable and battery so the connection seemed to be strong. Any feedback is very appreciated
 

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I'm no expert on this sort of an odd modification, but I do believe by grounding one of the field wires, you are making the regulator charge at full capacity. This is how we test output on the alternator in the vehicle, we ground the lower terminal of the regulator. The upper terminal, in the center, I believe should be connected to both the ignition run circuit and one of the alternator field wires. The other terminal should go to the other field on the alternator, not to ground or anywhere else. The case of the voltage regulator needs to be grounded, but that's all. 15V is a bit excessive in my opinion, but is within the normal range of most alternators. Typically voltage like that is only seen as normal when in extreme cold temperatures. You should see something more like 14.8V when charging normally with a heavy draw.
 

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So, does your tach still work? If it doesn't, fix it the right way. I'd bet that the PCM is still good in the truck and should be able to handle the job.

Also, there is no main battery in a dual battery system. They are both the same.
 

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That 12v from the battery needs to go to the ignition run circuit, otherwise you will be energizing the regulator all the time and run down the batteries eventually.
 

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Discussion Starter #6
on my electrical harness i found a spare electrical connector clip. I tested the wires on them and one of them got 12v power from the battery but ONLY when the truck is running So that's where i ran my 12v from by doing a splice their. It shouldn't drain my battery right? I mean that wire doesn't get any power when engine is off.

Also 15.10 seem to work ok. I took it on a 1 hour drive today and notice all my battery's are fine (thank God). Also on my gauge, the volt needle is just past the half way point and just barely under the "maximum normal range" area.
 

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Discussion Starter #7
Installed 3rd one with same issue.... getting around 14.90 to 15.70 keeps jumping back and forth and in between quickly.

What im installing is a KVR176A made in Taiwan OEM part from Cost Less Auto.


I even tried to ground it battery by sending one ground wire form voltage regulator bolt to the NEG battery...

What else could it be? Which ones do you recommend? Its gotta be this voltage regulator not meant for TWO battery's perhaps?
 

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Discussion Starter #9
Figured out my problem. I decided to double check my IGNITION HOT wire. When i turn my ignition on, i am getting 12volts out of that wire like i should..... However, for some reason i decided to double check the Voltage Regulator since it was my 4th one and i was also running out of ideas. So connecting the hot from the POS battery made my voltage run steady at 14.50 ...

So the wire that i was using is obviously causes my voltage regulator to jump from 14.90 to 16 every 2 seconds. So that is not a good power source, why its doing that i don't know. (It stays steady when wire being tested) Anyways, the wire i was using (if you have a 12vavle engine) i was using it off a spare 2 PIN clip that's empty and located right by the valve cover plate. It was the green wire.

Now that i figured out that its the wires fault (maybe has too many wires running through it) which possibly causing the regulator under power and makes it act up. (when not connected correctly, my fuse would blow inside the cab listed under "10amp ENGINE" .


So since problem is fixed, i am stuck again however. Where can i find a place to connect my new HOT wire? Obviously running it from POS will drain the battery over time. Where is a good source to get my power from on IGNITION on a 12vavle cummins? 94-98
 

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i have done this same "fix" to both my ctds. i did a complete computer delete on one of them. a genuine mopar brand regulator is a much better one. $30
 

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Discussion Starter #11
i have done this same "fix" to both my ctds. i did a complete computer delete on one of them. a genuine mopar brand regulator is a much better one. $30
Where do you get your hot source from? Same place? Do you add relay before you make the connection? thx
 

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Discussion Starter #12
When i verified the power coming from that wire, it was nice and steady and gave about the same exact voltage like the battery. So that's the tricky part, it seems its getting a clean power from their but obviously not because voltage regulator acts up and gets all jumpy like its on crack or something. But if i connect the voltage regulator directly to the power source from battery,everything is fine.

OK so i am gonna pick up a 30 amp relay from auto store and then wire it to the original wire that is (dirty) and hopefully that will solve my problem right?
 

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Discussion Starter #13
Wired in a 30 amp relay, is steady voltage now: I have a 30 amp fuse between my direct positive from battery that powers my relay. I also connected my (dirty but hot ON ignition wire) to the relay. Got 1 ground wire coming to relay. Finally a wire that leaves the relay to the voltage Regulator.

My truck gets 14.25 to 14.55 on a steady bases now with AC on and OFF. Question is, do these dodge ram ever go into 13's? Or is it always around 14 to 14.80 volts? My gauge on my speedo shows its normal but pushing the edge of the "max normal line." When i check with multimeter i get around 14.25 to 14.50 depends if AC is running or not.

Any information is helpful, thanks.
 

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Where do you get your hot source from? Same place? Do you add relay before you make the connection? thx
i took hot source from the power window fuse slot in the fuse box thing that hangs under the dash-neither of my trucks have power windows. no relay....

i use an after market volt gauge-i buy those 3-pack of volt/oil/water sunpro gauges from amazon for like $20, and all my dodges have them. i dont know how accurate the factory shit is, and my trucks dont even have numbers on the gauges, just a generic "range".
 

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Discussion Starter #15
yes thats all i have is the "range" ....What do you AVG? Ever go down as low as 13.5? Or always at 14?
 

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i can be around 15v, but am more apt to be 14.5v-ish
 

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You're making this way too difficult. Now, by adding an unnecessary relay, you're adding another variable that can introduce more problems and make it more difficult to troubleshoot in the future.

This is a common modification, but it could result in the "Check Engine light turning on. First you should diagnose the system to see if the voltage regulator inside the engine computer is really the problem. Chrysler has very little trouble with engine computers. I have some articles on my web site that detail how to troubleshoot Chrysler charging systems. I'm sorry that the site is still under construction and many of the pictures are wrong. There was a problem uploading photos and the ones there now were just for testing the system. I'll work on fixing the pictures if you will make use of the information.

The site is: randysrepairshop.com

Click on "Troubleshooting the Nippendenso Alternator".

Normally, you must measure 13.75 to 14.75 volts at the battery terminals while the engine is running. Less than 13.75 volts and the battery will not charge fully. Over 14.75 and you will start to boil the water out of the battery. Older GM batteries can tolerate a little higher voltage, and 15.2 or 15.4 volts is usually not catastrophic with most batteries.

Your charging system, as with most Chrysler systems, is extremely simple and reliable once you understand how it works. There is one thing they did though to complicate it, but there is a solution. You saw two small terminals on the back of the alternator. They are attached to the two brushes on the two ends of the spinning coil of wire, (the rotor). A previous poster is correct; they are interchangeable. However, the two wires going to those terminals go through a black plastic block. There's no easy way to be sure which wire goes to which terminal. Those two wires are definitely different and can not be mixed up.

On older cars that came with the external regulator you are trying to use, one wire was blue and one was green, and they were clipped onto the alternator separately. Either wire could be attached to either terminal.

The first thing you need to check is the voltages on the two small alternator terminals. One must have 12 volts, (actually full battery voltage). It will appear for only two seconds after turning on the ignition switch, then it will be there constantly when the engine is running. The voltage comes from the Automatic Shutdown (ASD) relay which also sends current to the injectors, coils, fuel pump or pump relay, and O2 sensor heaters. If the engine runs, the relay circuit is working. If the 12 volts is missing on one of the small alternator terminals, there has to be a break in the wire between the splice and the alternator. That's not common.

You'll get the most diagnostic information from the voltage reading on the second small alternator terminal. If it's very near zero, the brushes inside the alternator are worn. On a lot of vehicles they can be replaced without removing the alternator from the engine. The wire can also be grounded, (shorted to ground). That will result in zero volts on that terminal too, however the alternator would charge wide open.

If the system is working properly, the voltage on the second terminal will be less than battery voltage and more then zero, typically 4 - 11 volts. The lower the voltage, (which means the larger the difference or DROP across the two terminals), the larger the electromagnet, and the more output current leaving the alternator. If you find battery voltage on one terminal and less than battery voltage on the other terminal, yet the output current or voltage are too low, suspect an open diode in the alternator's output circuit. It will still work and may appear to test ok on a test bench, but it won't be able to pump as much maximum current as normal. Most off-the-car testers only test for output or lack of output, not specifically how much output because at maximum output, it takes more horsepower to run the alternators than the tester's motors can produce.

The third possibility is you will find full battery voltage on both small alternator terminals. This indicates an open circuit (break) in the wire going to the regulator, or the regulator is open. No current will flow, so no voltage will be dropped across the rotor. Think of a garden hose. If you step on the hose, the pressure (voltage) drops at the nozzle and the water dribbles onto your shoe! If you turn the nozzle off, you will build full water pressure at the nozzle even though you're still standing on the hose. Voltage in a wire works the same way.

You suspect your voltage regulator is open. That would stop current from flowing through the rotor, there would be no electromagnet, and no induced output voltage. If you are correct, you will measure the exact same voltage on both small alternator terminals. Grounding the proper terminal on the alternator will make it charge wide-open momentarily to prove the alternator and rest of the circuit is working. The problem is figuring out which terminal to ground. On older cars, it was always the green wire. On your truck, you can't easily tell which terminal to ground because the wires are both green and they go through that black plastic block. On my web site, I describe a trick to figure out which terminal is which, but that's more info. than you need here to fix your truck. You can ground this green wire at the engine computer too to do the same thing. Grounding it there includes the wire in the circuit, so you're testing it too right away. If grounding the wire right at the computer makes the alternator charge wide-open, the only possibilities left are an open regulator in the computer, or a spread terminal in the connector. The regulator is the most likely cause. That's a fast way of verifying ALL the rest of the circuit is capable of working correctly.

The whole charging circuit is one long series circuit; power source to alternator, alternator to regulator, regulator to ground. What you are trying to do is to remove the regulator in the computer and insert a different regulator not in the computer. Your regulator in the computer also uses one of the 12 volt supply wires to measure system voltage and one of the ground wires to compare the voltage to. Your new external regulator does exactly the same thing. The 12 volt feed wire powers the regulator's circuitry and is where it measures system voltage; the ground is the regulator's case that has to be bolted to a clean shiny spot on the body sheet metal.

In the picture you posted, there's a note on top that says the two wires to the alternator can be switched. That's only true if the black plastic block with the attached wires is removed. Then you can run wires all over the place. This is where you are making things way too complicated. If you have that block off now, with the engine running, find which one of those two terminals in the block has the full battery voltage. Put the block back on the alternator, then attached another wire on that terminal and run it to the one marked "12 volt from battery" on your picture. It will turn off anytime the engine is not rotating so it won't kill the battery. It's doing exactly the same thing you want to do with another relay, except it's much more effective. Add a second wire to the other small alternator terminal and run it to the second regulator terminal. Ground the regulator, and you're done. It can be even easier to cut the green wire at the engine computer and just pull it over to the regulator and attach it instead of running a new wire.

These external regulators have temperature compensation built in just like your original unit in the computer. Charging a battery is a chemical reaction. Chemical reactions occur more slowly in cold temperatures, so to help the battery charge in cold weather, they raise the desired charging voltage a little. That's where it can be acceptable to find a little more than 14.75 volts across the battery terminals. The other thing to be aware of is the engine computer monitors operation of the voltage regulator. When it fails to see the current flow through the regulator, it assumes there is no current flow through the field winding, (rotor), and therefore no output from the alternator. This will result in low voltage to the injectors, coil(s), and fuel pump. Although the truck might run fine for a long time, these things can cause a change in tail pipe emissions that the engine computer can't control. That is cause to turn on the "Check Engine" light on the dash. While driving it this way won't hurt anything, if a different, unrelated problem occurs that would result in the light turning on, you will never know because the light is already on. The typical diagnostic fault code that will be in the engine computer's memory would be "Field current not switching properly". The computer can't monitor the external regulator so it will just be up to you to watch the dash gauge and headlights for symptoms. These external regulators are also very reliable. Most lasted the life of the car. 99 percent of junkyard units will be fine too but watch out for rust on the case that could interfere with a good ground.

The last thing you will lose is modification of charging system voltage based on outside circumstances. Full output from a 100 amp alternator can easily draw ten horsepower from the engine. That ten horsepower might be just what you need to complete the pass in time or make it up a steep hill while pulling a trailer. At wide-open-throttle, the computer will command the regulator to turn the alternator off for a short time so that ten horsepower is available for other stuff. Some cars will bump up the charging voltage a little when the rear defroster is turned on. If the engine is running hotter than normal, such as when stuck in traffic, the engine computer might lower the charging voltage to reduce the load on the engine. Everything the engine computer knows can be used when making decisions on selecting the desired charging system voltage. None of that was really necessary years ago when cars were much simpler and more reliable before they added all the computers to them.

See how far this gets you. If you want to troubleshoot the original charging system, measure the voltages on the two small field terminals on the alternator while the engine is running, then holler back.

caradiodoc
[email protected]
 

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Hi guy, i was reading this post because something weird happening to me with my 2008 dodge ram 2500 cummins 5.9, last days i have been instaled a kenwood double din unit in it, and last night i was watching with hight volume a video with engine off and switch key in accesories for about an hour, and when i start the engine this start to spin kinda low but finally started, the very rare thing here is if the engine running, why the alternat doesn't charge!!!!!!!, any idea guys???
This is that i thing to happen: if the chrysler charging system is designed to supply power to all devices of the truck and charge the batteries just in a surface level, could be 95% of his capacity, and when, for a several reason or batteries are too old, you is taking power from batteries with engine off, and the % level down below the 95%, the pcm directly don't exite the alternator, or change batteries, or charge them til they reach at least 95% of his charge, maybe i'm wrong, what you say about this??? Thanx in advance.-
 

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FIXED!!!! was both batteries!!! and was as i wrote above, the pcm exite the alternator only if both batteries are at 95% of his charge or more, below that, the pcm let the alternator anactive until recharge the batteries individually or directly change the batteries, this cause that the check gages light on first and then check engines lights on too.-
 
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