Need some help with a direction to go with charging system ?

I would ask for your thoughts on the next step in a repair or replacement of my charging system.

I'm on my second voltage regulator. The repair manual is great if you have a "know good regulator or a alternator". Some help.
I now have a 14 volt read light on the regulator.(better than no lights on the other one) In the testing I'm at the point of needing a "know good one".
This will point me to ether another regulator or alternator. (I used both the military tests and the C.E. Niehoff & Co.

So here are my choices.

Get another regulator. $$$ used or old new ?

Get a alternator with a regulator $$$$ used ?

Or just get rid of the stock stuff and go with a aftermarket system $$$$ and that I can get parts for without all the "Military problems" ?

I don't want to be on the road with something that seem to be less than ideal. I'm not in the Army any more.

Thanks for the input .

Did you visit the Niehoff website troubleshooting section? Someone here installed a HMMWV 200A unit and it worked out, no idea where that thread is.

24v green with 14v red light is usually an over charge indicator. Could be a number of things. I would start by cleaning every contact and ground on the alt and on the batts. Take a look at the polarity box under the spare tire. Its only there to prevent reverse polarity and you get about 1/3 of a volt drop across it since its basically just a big diode. Are you still using the original excite wire or have you switched over to the fuel solenoid positive for excitiation? Is there anything connected to the other regulator terminal?

14v = RED, 28V = No Light.

Rewired your way.(thanks Suprman)

Have not pulled the spare and looked at the polarity box.( will do that today )

Ends all clean at the battery and Atl.

On first start (after sitting overnight ) I see the Atl. try to make 28+ volts then back to battery voltage +- in maybe a second or two. Tried the reset with no luck.

Can the polarity box be removed ? And was this for protecting the truck for our soldiers ?

You can bypass the polarity box. It is there to protect against the batteries being installed backwards. You can check the ground from the frame to cab its behind the grill on the passenger side. Check the alternator to regulator connection. Have seen corrosion there before. Is there anything connected on the other regulator terminal? On the newer style alternator, which you have since it has the leds, the rear regulator terminal is an AC output used to power a tach or other accessory. On the older alts that originally came with the truck it was a field sense connection.

I will take a look at that,Will. Need to look for the chassis to cab ground.

Nothing on the tach feed, yet. I have not installed my tach yet.

Funny thing is it was ok for about 5 short trips then poof, low gauge and red light.

Maybe issue with the alternator itself. Maybe follow the niehoff troubleshooting guide. It will have you take some measurements on the alt. See what the results are.

Yep ,did the a to d and a to b and d to b stuff. 2.1. OL ( my meter reads,ouch) (this looks to be a winding and diode test ? ) Then its back to having a "Known Good Regulator " thing.

you have a READ light on the 14V side. so if it is Red then that signals overvoltage what is the Voltage on your 14Volt Terminal on the alternator? double check that number and if possible check each battery to see if one is higher than the other. another test would be to swap the top and bottom battery positions to try and "rebalance" the system.

I have seen shorts in the dash cause 24 volts to get onto the 12 volt circuit.

Will,do you want the motor running or not ?

Back to basics. You need to do some precise voltage measurements, including the following:

At the battery box:
- 12v battery voltage with engine off. Should be 12v or a little higher.
- 24v battery voltage with engine off. Should be 24v or a little higher.

An LMTV will start even if one pair of the batteries is shot (high resistance cells). Voltage can read ok! Then when the alternator tries to charge, battery voltage across that pair goes sky high and the regulator either tried to control it by dropping charge voltage, or shuts off.

At the PDP power distribution panel, master (green) switch on":
- Both voltages should be slightly less than battery voltages due to drop through Polarity Protection box.

If either of those voltages are not present then troubleshoot a problem other than alternator/regulator.

Then start the engine but monitor the 24v battery voltage as you start:
- Did the 24v hold up ok or did it drop significantly? This checks the batteries under load.

With engine running:
- the 12v battery, and the 12 v at the PDP should increase to at least 13.5 to 14.5 volts
- the 24v battery, and the 24 v at the PDP should increase to at least 27 to 29 volts.

In your description of the problem you mention the lights, but no voltages. If you do not know all the voltages above, there's no way to start guessing at the fault.

You can also verify excitation voltage at the alternator/regulator, the voltage you will find on the modification you said you did. Did you get excitation voltage?

All those voltage measurements can be made to a good ground. If the measurements are questionable, put the VM red lead on the battery negative buss and the black lead on a clean chassis ground and see if there is voltage when you start the truck. A voltage reading, even a few volts, says you have a ground reference problem.

Using a long ground (-) lead on the VM, connected to the battery negatives and left there, will help avoid grounding issues as you make voltage measurements around the truck.

I did what Will suggested with the battery's. Changed position. Only using 2, 12 volt battery's.

After that I did first start of the day. Battery's read 12.4 and 12.1
Now showing 18 v and 30 v running at the Alt.
Flashing amber at 14v led and flashing red 28v led. Every once in a wile I get flashing green on both.
Gauge a dash is now showing 30+ v.

As for the start their is a big drop under cranking. At dash maybe 18 volts cranking.

Just did start #2 .Dash voltage below 24v. Red flashing at 14 led and amber at 28 led.
Then only red at 14 led and no light at 28 led.
Tried reset. At gauge 28v for a second then below 24v.

Starting to look like low CCA's.? Battery's test at 891 CCA.

Going to pull the spare and take a look at the RP box.

What changed between Start #1 and Start #2? Batteries? Sounds like you've got more than one with bad cell or shorted internally?

1951M1078 said:

I did what Will suggested with the battery's. Changed position. Only using 2, 12 volt battery's.

After that I did first start of the day. Battery's read 12.4 and 12.1
Now showing 18 v and 30 v running at the Alt.
Flashing amber at 14v led and flashing red 28v led. Every once in a wile I get flashing green on both.
Gauge a dash is now showing 30+ v.

As for the start their is a big drop under cranking. At dash maybe 18 volts cranking.

Just did start #2 .Dash voltage below 24v. Red flashing at 14 led and amber at 28 led.
Then only red at 14 led and no light at 28 led.
Tried reset. At gauge 28v for a second then below 24v.

Starting to look like low CCA's.? Battery's test at 891 CCA.

Going to pull the spare and take a look at the RP box.

Click to expand...

Nothing that I know of ? Battery's pass a capacitance test (Snap-on) ?

Went looking for grounds. Found one at the starter. It looks to be just a post. But it was not tight.
Pulled it off cleaned the lines and install 2 star washers and reinstalled.

No luck,dip on voltage was not as low but only charged for two seconds the back to battery voltage.
At Alt. flashing red at 14v led and flashing amber at 28v led.
Then after about 30 sec. RED at 14v at led and no light at 28v led.
Tried reset and start flashing red and amber and then Red only at 14v led.

Going to try new battery's ?

what was the Ohms reading of the Field Coil Pin A to D? also un plug the Regulator and then start the truck and see if the voltage climbs if so you may have a shorted field coil.

2.1

ok so another thought have you tried Static Testing the LBCD? http://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG53B_uid1252012258102.pdf
this requires you remove the terminals from it but it could be that the LBCD is disconnecting the batteries and its internal capacitors are bad and the system is acting like its battery less and the ALT/Regulator cant drop the voltage down.

This truck doesn't have that.
Only the revers polarity box.

For sure it thinks their is a voltage problem.