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External Voltage Regulator Install

165K views 24 replies 15 participants last post by  1982Cummins 
G
#1 ·
Ok guys and gals. After doing some researching and studying old pics I had, I have come up with a diagram that will show you how to wire in an external voltage regulator for when your internal regulator in the PCM quits working. Symptoms are either no charge or overcharge, however they are designed to fail in a no charge state.

After insuring your alternator, batteries, and crank sensor are all good you can then use this diagram and save yourself about $800 on a new PCM. The alternator is a open field external regulated type. There fore it makes it easy to do this mod.

What you will need is a voltage regulator from an 89' or older Dodge/Chrysler vehicle, a plug with harness, several pieces of wire, three barrel crimp connectors, two small ring and one large ring connectors, crimp tool, black tape, cordless drill, 2 self tapping sheet metal screws.

First you will need to find a secure place on the fender well or firewall to mount the voltage regulator. Once a location is selected make sure to Sand the area down to bare metal where the screws you use to mount the regulator will make a good ground. Then on the back of the alternator you need to take the two small nuts off holding the black plastic formed block on. Once the block is removed, tape it up so as it can not touch any metal and cause a short. Then take the two small ring connectors that will fit the studs on the back of the alternator and crimp them onto two lengths of wire that will reach from the alternator to the voltage regulator. After crimping the connectors onto the wires, connect one each on the back of the alternator and tighten the nuts back up. Then route the wires from the alternator back to the voltage regulator. Next use your large ring connector and crimp it onto a piece of wire that will reach from your battery to the regulator. Route the wire from the battery to regulator, but DO NOT hook it up to the battery at this time. Now take one of the wires from the alternator and the wire from the battery and twist them together, then crimp them into one end of the barrel connector. Then take the other end of the barrel connector and crimp it onto the wire from the regulator plug that goes to the TOP post on the regulator. This is very important, it must be the wire going to the TOP post or you will pop the regulator. Then take the remaining wire from the plug and the alternator and crimp them together using the other barrel connector.

Now go back and hook the wire onto your battery post. Start your truck and verify that is charging. Put your tools away and go buy yourself another mod since you just saved $800 from not buying a new PCM.


 
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1
G
#2 ·
Yes, this will also work on Dodge gas powered trucks and vans. Actually any Dodge/Chrysler product that uses this type of alternator and computer controlled charging circut. Just a few days after writing this article my employee called and said my work van (97' 2500 w/318) was dead. We got it home and yanked the alternator and it checked good, so I knew what was wrong. Anyways I have two part numbers now from O'reilly Auto Parts.

Voltage Regulator part# MPI R296 - $14.99
Pigtail/Plug part# BWD PT173 - $5.69
 
#3 ·
>
Bouncer said:
I have come up with a diagram that will show you how to >wire in an external voltage regulator for when your internal regulator in the >PCM quits working.

I just did this conversion after my charging just completely died on my '94 Ram 1500 gas 5.2. It worked!

But one issue: the Check Engine light stays on. When I check the codes after the fix they are the same as before the fix (12; 37; 41; 55). Code 37 is no problem, it has always been there since I bought the truck used. That code seems meaningless for my gas 5.2 truck.
But the 12 and 41 codes make sense except that I fixed the charging problem.
Will the check engine light ever go out?

Great job with the diagram and description! It gave me the confidence to do this mod. Thanks.

Al
 
#5 ·
question on install

:mafia1::fan
Ok guys and gals. After doing some researching and studying old pics I had, I have come up with a diagram that will show you how to wire in an external voltage regulator for when your internal regulator in the PCM quits working. Symptoms are either no charge or overcharge, however they are designed to fail in a no charge state.

After insuring your alternator, batteries, and crank sensor are all good you can then use this diagram and save yourself about $800 on a new PCM. The alternator is a open field external regulated type. There fore it makes it easy to do this mod.

What you will need is a voltage regulator from an 89' or older Dodge/Chrysler vehicle, a plug with harness, several pieces of wire, three barrel crimp connectors, two small ring and one large ring connectors, crimp tool, black tape, cordless drill, 2 self tapping sheet metal screws.

First you will need to find a secure place on the fender well or firewall to mount the voltage regulator. Once a location is selected make sure to Sand the area down to bare metal where the screws you use to mount the regulator will make a good ground. Then on the back of the alternator you need to take the two small nuts off holding the black plastic formed block on. Once the block is removed, tape it up so as it can not touch any metal and cause a short. Then take the two small ring connectors that will fit the studs on the back of the alternator and crimp them onto two lengths of wire that will reach from the alternator to the voltage regulator. After crimping the connectors onto the wires, connect one each on the back of the alternator and tighten the nuts back up. Then route the wires from the alternator back to the voltage regulator. Next use your large ring connector and crimp it onto a piece of wire that will reach from your battery to the regulator. Route the wire from the battery to regulator, but DO NOT hook it up to the battery at this time. Now take one of the wires from the alternator and the wire from the battery and twist them together, then crimp them into one end of the barrel connector. Then take the other end of the barrel connector and crimp it onto the wire from the regulator plug that goes to the TOP post on the regulator. This is very important, it must be the wire going to the TOP post or you will pop the regulator. Then take the remaining wire from the plug and the alternator and crimp them together using the other barrel connector.

Now go back and hook the wire onto your battery post. Start your truck and verify that is charging. Put your tools away and go buy yourself another mod since you just saved $800 from not buying a new PCM.


 
#9 ·
External Voltage Regulator?

Hey guys I'm thinkin its my voltage regulator, I have 98 dodge ram 12 valve and I not knowing put in a shorted battery in, so I'm on the highway and gauges start going wack truck stalled so I changed the the batteries to some optima red tops. So after that my ats commmander starts flickering engaging the TC at a dead stop and gauge pod lights flicker and its been getting worse so I changed the alternator and still the same thing. I don't have a problem with charging I maintain 13.4-13.9v at an idle. Any input?
 
#13 ·
regulator install

paul, make sure that your 12 volts is going to the correct post on the regulator, and that you have scraped the paint where you mounted it. I ran my 12 volts from an ignition switched source. If you have 12 volts going to it, it could either be a faulty regulator, or the diode in your alternator could be bad.
 
#14 ·
As said above, verify all your connections are done properly. If you applied the 12v on the wrong post of the regulator for even a second, it is ruined. You need to verify your alternator is good and that is not the culprit, also very unlikely, but your gauge could be bad.
 
#15 ·
Alternator

Please review the Charging system schematic for the 98 dodge ram 1500. I wired the system per the instructions and the schematic from this thread, but the + and - fields on the back of the alternator are opposite on the drawing that I have attached. I will go back recheck everything again. Please let me know what you think.
 

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#19 ·
There is only four possible options.

1. You installed it incorrectly
2. The regulator is bad
3. The alternator is bad and allowing the circuit to go straight to ground
4. You have another problem also that needs to be found
 
#20 ·
Positive connection?

In the image you supplied and the instructions you have provided Bouncer you have indicated to be sure and attach positive power to the top post of the regulator and people seem to have problems from draining batteries to miscellaneous lights being on using your wiring diagram so my question is, as the regulator you have pictured is an "A" circuit regulator which means it controls output of the alternator by controlling the negative side of the input to the alternator, why are you suggesting a postive power supply be attached to that two wire regulator?
 
#22 ·
In the image you supplied and the instructions you have provided Bouncer you have indicated to be sure and attach positive power to the top post of the regulator and people seem to have problems from draining batteries to miscellaneous lights being on using your wiring diagram so my question is, as the regulator you have pictured is an "A" circuit regulator which means it controls output of the alternator by controlling the negative side of the input to the alternator, why are you suggesting a postive power supply be attached to that two wire regulator?
pacozoid

This is a solid state device, it will not work without a + and - connection............

Just wondering if people are disconnecting the existing field wiring before trying to connect an external regulator...................don't think you want to be running 12V into the computer......

Also it is best to tie a ground wire to the case of the regulator

Is there anybody out there............................ :)

bobloes
 
#21 ·
First post................. 1995 Ram Van B1500 3.9:)

1 This MUST be connected to a switched + power source, IGN, if you do not, it will discharge the battery through the regulator.

2 It works properly, charge 14.X V

3 Any way to make the check engine light go off, short of replacing the computer module.

Thank you

bobloes
 
#23 ·
Considering this for my 92 B250 van, having ignition-ish problems(burning up the fusible link going to my fuel pump and CEL), thinking maybe the one in my ECM has catastrophically failed. So this sounds easy enough, and it really doesn't matter which alt wire goes to which post of the plug, as long as the batt + goes to the top one?
 
#24 ·
am3, the diagram on first page is 100% accurate, to your question, it dose not matter witch line goes to witch, as long as the 12v is top post, i just recently put this mod into my 1990 dodge b150 and worked like a charm, but there was 1 thing to take note of...

after i got everything in, it drained my battery, i have not not yet added anything like a relay for it, all i have done (quick fix) was got a switch that could support the amperage and voltage, all so wired in a led when i had the switch on so i could tell if it was not on or was (human error sux sometimes and a lil light helps lol)

hope this helps
 
#25 ·
Voltage Regulator Conversion Help

Hello, I have a 1982 dodge cummins diesel crew cab 4x4 conversion I am finishing. The electrical is last major hurdle. I hooked up the 1994 cummins alternator to the 1982 dodge wiring. It worked however, I was reading 18 volts at idle at the battery. I disconnected the alternator as I assumed this was not correct and too much voltage. I am now attempting the dodge voltage regulator conversion. I have the wiring completed as Bouncer describes; one field wire combined with a hot wire (when ignition is on) to top post of the regulator and the other field wire hooked up on the other location of the regulator.
The question I have is what to do with the large electrical connector on the alternator that stays hot, I believe the direct battery connection. I did not hook it up but checked the voltage, it was putting out 32 volts at idle. Assume that it would have to be hooked up for the system to charge. Didn't think that the two field wires were only ones connected but maybe I am wrong. Any help would be appreciated.
 
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