OK, I had issues with alternator for awhile. The voltage would be at 10 volts when starting and slowly drop to 8 volts after running. Figured alternator because when when measure withm eter at battery, was only reading 12 volts and it would slowly drop. Tested alternator and tested bad. Replaced. Ran good for week, then same thing. Another bad alternator. Replaced. Checked codes, 1682, 0622,0500,1765,1693, 0501. Figured the pcm isn't seeing whati t needs to see to turn on alternator. I installed the external VR to the firewall, after sandig the paint off (good ground). Wired the blue wire to the Vr, top post, to a switched hot when key is on and added a wire to run to the altenator. Ran the green wire to the other alternator post. Cut the original pigtail from the altenator and crimped in the new wires. Taped off the two old wires and left them. Start he truck, after I charged the batteries to full. TRuck starts and idles at measured 14.8 volts to batteries. Gauge reads 10 volts, slowly climbing to 14 volts, then climbs to 18 volts and check gauge light comes on. When it hit about 16 volts on gauge, the lights start to flicker up and down and there is a noise from the motor raising and dropping. All this time the measured voltage at the batteries is 14.4-14.8 volts. Scan gaugeII verifies 14.8 volts throughout process and never changes. What next?

2002 dodge cummins, auto, 4x4.

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Heading out now to ensure the trucks even starts and check the voltage at External VR and at batteries. Might take out batteries (Optima red tops) and have them tested. They are only about 4 years old. Maybe check the connections? At this point I am not quite sure which way to go and what to check. I thought by installing external VR, I would be bypassing the cam sensor and the pcm for alternator control?

My marine battery charger puts out 14.8 when charging in full bulk charge on the rv and my first generation truck charges at 14.7 all the time.Don't know if this helps at all. I've heard that the old Ford regulators are adjustable by turning a screw you can adjust it up or down. Another thing to consider is the batteries internal resistance to accepting a full charge. That is why the better charge will pump higher voltages to bring the batteries stored voltage up and help desulphate and reactivate the battery's storage capacity.

I bought the VR that mopar man suggested. Just not sure why the Vr will put out the correct voltage, but the truck gauge maxes out and flickers lights.

Not sure why it would do that either. Does it do that when it hits 18 volts? I know that's too high.As soon as Mike gets his 6 cups of coffee:drool: He'll be right on this.I wonder if the new voltage regulator sees the voltage drop from the grid heaters coming on and then tries to compensate for that big load.I'm interested since I want to install an external VR and would like to help anyway. The engine sensors are getting kicked with the wrong voltage perhaps, is why the error codes. But, I really know so little

The run up to 18 volts happens long after the grid heaters have cycled. It happens after the trucks has run for 20 mins and going down the road at 45 mph. It doesn't drop back down until I shut it off and start it again, then the same thing. I would theink that maybe the gauge is bad, but the lights flickering and the motor sound leads me to believe that the voltage increase is real somewhere in the pcm or ecm.

I think your right there, the gauge is just showing voltage level.... Is it possible The VR is bad? Wires hooked up correctly? I know I'd dbl check. Another thought is and I can't remember, if there is a wire that is supposed to be disconnected from the PCM now that there's an external VR.The only time I ever saw a voltage spike like that was when I had a bad ground to the chassi. All the gauges were reading too high until I found it. Shoot.... do I even remember that right?

Going over grounds now. Replacing battery connections with new and then on to grounds.

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New connections on batteries. Batteries, unhooked voltage = 12.5 volts. All grounds intact. Ohmed from alternator body to neg batt= grounded. Body to engine= grounded. Started truck. Voltmeter on battery reads

14.7 - 15.0 volts on both batteries. Scan gauge II reads 14.5-15.0 volts, steady. Gauge in truck took a few minutes but ramped up to 18 volts and stayed there with check gauges on. Lights still pulsing. AC voltage at batteries = .028. What else could possibly be going on? Mike, you around?

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Ok, mistake on ac voltage at batteries. DC voltage = 14.7 volts. AC voltage = 167.4 milivolts. When the guage ramps up to 18 volts, inside the truck and the check gauges light comes on, the DC voltage at batteries is still reading 14.7- 15.0 volts, but the AV voltage goes up to 200.6 millivolts. Any suggestions?

Please let me know what you find. I need to do this to my truck sometime soon.BTW, Did you follow Mopar's wiring article? Assuming you did... I sent a PM to Mike about this.

Followed his article exactly. Truck is charging, just gauge reads very high after while and lights are pulsing. I guess the lights pulsing are due to the VR. Just not sure what the next step is.

Wish Mike would chime in. If you are sure about your connections I would take the VR back for another one. I have also read that batteries act like a big resistor/ capacitor so I' m guessing here..... What if the VR was hooked to the battery furthest away from the PCM? Would that steady the voltage and pulsing?I'm afraid I'm not much help.

Jag, I apprecaite all your help! That's about where I am at, another VR or take it to the dealer for a new pcm. I am at my wit's end with this truck.

Sorry for the lag. Something is wrong with the setup of the external voltage regulator. The first thing is the blue lead is suppose to be positive voltage +12. Typically you can tap the existing blue lead for this 12 volts. As for the green wire it should be only hooked between the alternator and the new regulator. The old green should be disconnected.

1682, 0622,0500,1765,1693, 0501

P1682 http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/224-p1682-charging-system-voltage-too-low P0622 http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/205-p0622-generator-field-not-switching-properly p0500 http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/190-p0500-no-vehicle-speed-sensor-signal p1765 http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/388-p1765-trans-12-volt-supply-relay-cntrl-circuit p0501 http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/191-p0501-vehicle-speed-signal-rationality The 1765 and P0622 worry me. You should look into those a bit deep and see if there is a blue wire supply problem.

I unhooked the blue and green from the alternator and taped them, individually. I ran a new blue wire from the alternator F1 to the new ext VR. I also ran a new blue wire from the fuse box, under the hood, at a tested +12 volts to the ext VR. These two blue wires, I crimped them together and attached to the lonely triange post at the ext VR. I then ran a separate green wire from the other post on the ext VR to the alternator, F2. Sound right?

Correct.

Mike, What would cause the ramp up in the truck gauge to read 18 volts and the check gauge to come on? The voltage measured at the batteries and the scan gauge is a constant 14.5 - 15 volts. I removed the wires from the heater grid to make sure they aren't pulling down the charging system.

Do a instrument cluster test.

If the cluster is getting a different reading its because I think the PCM is screwed up and mis-reporting the voltage of the system.

Gonna try it right now. Back in a minute with results.

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Ran the gauge cluster check, no codes. Everything worked just like your video.

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Does the PCM report a different reading to the cluster than it does to the OBDII port?

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where would the best place be to order a new pcm? The dealer has qouted me $1100 for diagnostic test, pcm repalcement and programming. Is there any other route worth taking?

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Mike, I know you are a very busy man and full of knowledge. If you could take a look at what I am dealing with I would greatly appreciate your help. JUst not sure which way to go with this overcharging situation.

As for the over charging issues there is something grounding the green lead? If so then the alternator will be in full runaway mode. The blue wire is the power supply to excite the rotor in the alternator.

So at the GEN SOURCE and the GEN FIELD of the PCM would be where you hook the External Voltage Regulator. As you can see you need the blue wire which is the 12V and the Green wire is going to be a variable ground. If its shorted to ground then you got a runaway alternator. So I would think the regulator is fried if so.

I used the gen source wire as my +12 volts for the VR. I used a connector and tied the two wires together to go the VR. So one wire goes From the Gen source (+12) to the top post of the VR. I added a seperate wire with this one to go from the Vr top post to the gen. The other wire goes from the gen to to the bottom post of the VR. The altternator (gen) is not in runaway. It is producing 14.5- 15 volts constantly. The problem is that the lights (all lights) are pulsing and the volt meter in the truck runs up to 18 volts after about 10 mins run time and triggers the check gauges light. The alternator is producing 14.5 - 15 volts constantly, measured with a Fluke 75 meter.

Sound like you did it right its just there is something wrong with that PCM.

Ordered a PCM from Auto Module Source today. I sent them my vin # and all pertinent info and they said no problem. Should I erase all codes before changing it out? I also orderd the ECU as well, just to be sure. It just really doesn't make any sense as to where the gauge would see the voltage increase and trigger the check gauge lamp when the alternator is taken out of the circuit. The PCM is generating this signal from somewhere and sending it only to the gauge, nowhere else.