M1083 Finally (MAY HAVE) a working alternator >>>> BUT !

[Alexandninasdad]

Unbelievable drama securing a Alternator .. but thats a Rant . Lets start over ..

96 M1083 Purchased in Ogden UT from a company that used to turn these into Overland campers. The truck is a runner but charging is a problem .
The Charge gauge was in the Lower part of yellow and that Alternator tested bad by a Proper Shop. Now i've finally installed what I HOPE is a good alternator after
replacing all LG gauge cables ($$$) to the Alternator and the Battery Box and the >> ?? POLARITY THING << under the spare tire. Does it have a Name ?

Today I took the Batteries to the car parts store for a 12.6v charge and Bench test. All are A-OK. Subsequently the truck starts on the spot. Runs happily etc.

HOWEVER
> Charge Gauge still in the Yellow.
> Output at the Alternator at the YELLOW (front) terminal is 24.5 V Engine Running
> Output at the RED (back) is 12.5 V Engine Running
> Voltage @ Energize Terminal on Regulator Right was 24v
> Voltage Checked at the Batteries all four showed 12.3 V
{??} According to the CE Niehoff Docs i have referenced the Yellow terminal /Front should put out 14V and the Red / Back 28v .... IDK

SO .. I have no wiring diagram to reference in the Manuals I purchased online.. and I need to know what wires go where from the >> Mystery Item under the Spare tire << and what the voltage is supposed to be at each of those 4 Connections.

Additional Details which may not have any bearing at all ===================================================================================================

The INOP Alternator that I removed had the Regulator with LED indicator Lights. # 76761 N1511

The Alternator I installed is : 12420852RB with a 67671-N3030

Voltage output of the INOP alternator that i removed was not noted / Labeled.. i only labled the wires i removed with Red/Yellow.

NO Battery wiring Diagram to be found under the lid of the Battery Box

4 Automotive Batteries are now in the Battery box

 

[chucky]

Power distribution device is the name of the box behind spare tire! Did you take the cables off of that box and clean the rusty studs and cable ends? Are both lights on altenator blinking green with truck running ? Take a metor and see what the altenator is putting oput at the altenator with truck running and bump the hand throttle up to 1000 rpm or above an idle then go to the batteries and see if the same voltage is getting back to the batteries and make sure all the cables and post are clean and all the guys that know these trucks will tell you to add big ground cables at altenator and extra at batt box . See if any of that helps

 

[chucky]

The 4 studs are at least on my 97 1083 the top 2 are 24 and the bottom 2 are 12 volt on each one cable coming in is batt cbl comin to box and the other stud will be the altenator coming to pdd box there is some kind of amp fuse internally in the box by testing the voltages at that box if your making 14 at alt and it aint geeting to the battery you might have a fuse burnt

 

[Alexandninasdad]

I Replaced all of the cables with new, cleaned up that Power Dist Box and the collective ground next to it. The New Alt regulator has no lights. However I was able to Start & Drive for 170 Miles ... on the freeway so must be getting some voltage... I hope. Gauges that read incorrectly / bad are Charging, Fuel level, and maybe temp. So i will go after the ground at the front of the cab and make sure that's all cleaned up. >> Will I cause any damage if i Disconnect the Alt output cables from Alternator while the engine is running? I need to know more about this inline fuse ...

 

[chucky]

The fuse i was refering to was internal in the pdd box ! all you can do is test inbound and out bound current to make sure its going all the way thru the box if not its in the box and if thats what you find put all the same voltage cables on 1 stud there fore by passing the internal fuse and if you do this you will have to make sure not to hook up any battery cables backwards or as it was put to me {puff up in smoke a lot of expensive stuff} so be careful. And as far as takeing off cables while running i have no idea but i wouldnt see the need just meter it at the termaminal on the alt and you said in your first post you put a 3030 voltage reg on the truck ?mine has 2 lights one for each current 12 and 24 if all good they both blink green back and forth if not they blink orange/red

 

[Alexandninasdad]

The fuse i was refering to was internal in the pdd box ! all you can do is test inbound and out bound current to make sure its going all the way thru the box if not its in the box and if thats what you find put all the same voltage cables on 1 stud there fore by passing the internal fuse and if you do this you will have to make sure not to hook up any battery cables backwards or as it was put to me {puff up in smoke a lot of expensive stuff} so be careful. And as far as takeing off cables while running i have no idea but i wouldnt see the need just meter it at the termaminal on the alt and you said in your first post you put a 3030 voltage reg on the truck ?mine has 2 lights one for each current 12 and 24 if all good they both blink green back and forth if not they blink orange/red

I will chk all voltages and post a diagram to incl voltage readouts. Perhaps that will clarify what I have .. ( I'm a visual thinker more than verbal ).

 

[mechanicjim]

with all niehoff alternators the colors are Red 24v/28v and yellow 12v/14v, with engine off you should have 24v at the red stud and 12v on the other. https://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG0018A_uid12172009221392.pdf
see image on page 2 of the link.
i think you have the cables for 24V and 12V swapped. that is the only way you would wind up with the difference in voltage you are seeing.
if you look at the Alternator from the front 11 o'clock terminal is 24v and 10 o'clock is 12v
for the box under spare see if it looks like the LBCD in the following guide page 7

https://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG0014D_uid12172009224052.pdf

if it does its a LBCD if not it just the base PPD (polarity protection device)

 

[Kbarnes0]

I'm going to need to check the voltages on mine. My alt tested good, put the new N3207 regulator on and now have green lights flashing indicted a charge. Dash Gauge slightly in the green. After today's run on the hyw it pretty much stayed in the top part of yellow the with everything on or off.

Im thinking with really good batteries the alt barely puts out a charge?

Im check the actual output tomorrow and compare to the gauge

 

[Alexandninasdad]

Given:
8/20 Alternator N1506-1 Regulator N3030 (No Indicator Lights)
-------------------------------------------------------------------------
6/2020
> Ground strap Removed / cleaned Connex then re-installed
8/2020
> Replaced all Cables between the Alternator and Battery Box. Cleaned Connex @ Elecronic Box under Spare.
> Installed Alternator from Grigsby Trucks. ( See Given )
10/2020
>Removed all 4 EXIDE Batteries and took them to be Charged and Bench tested. < RESULT : A-OK >
>Installed/connected Solar Battery Maintainer to the two Rear Batteries < REASON : Back Ones Read a Lower Voltage than front two >
>Installed 2ea Battery Disconnects one each on the 12V and 24V battery Cables.
> Visual Check for Obvious signs of Damage @ Gas Pedal to wiring Loom at the Sheet metal Bung / Pass-thru < RESULT : Looks A-OK
11/2020
[ ! ] RE - check of voltages at the Large Alternator charge studs show cables are REVERSED. Swapped and gauge reads almost green.

 

[Kbarnes0]

CONTINUING:
Long story short it seems the new Replacement Alternator is not charging either. My Bad .. I did not have it bench tested prior to Install as it looks Amazing. I took a Longer Drive and ( it seems ) eventually the batteries no longer had enough juice to keep the Engine and the Trans ECU powered. Loss of Power at Full throttle on the Freeway, I pulled over ASAP and lost all forward motion shortly thereafter. I turned the Engine off and there was not enough Juice to Restart. ( Some Time Passes) A Big Rig Service/Rescue truck came along and connected his Battery bank to mine and SURPRISE the Voltage Gauge moved up into the Yellow range ... ergo the Voltage Gauge does seem to work. ( Right ? )

( Side Note - ! ) The Prior owner scrapped the Military Batteries and Substituted 4 Matching Car Batteries. This I did not question as that Guy works on the 10 Ton Military trucks for PLAN B in Ogden UT. ANY THOUGHTS ?

I will start RE-examining the ENTIRE System from scratch and reflect my notes and DMM readings here. I will Start by following the Niehoff troubleshooting Guide as well as a thread I came across on this site.

8/2020
> Replaced all Cables between the Alternator and Battery Box. Cleaned Connex at Junction Box under Spare.
> Installed Alternator from Grigsby Trucks.
10/2020
>Removed all 4 EXIDE Batteries and took them to be Bench Charged and trested.
>Installed/connected Solar Battery Maintainers to the two Rear Batteries ( They Read a Lower Voltage than front two )
>Installed 2ea Battery Disconnects one each for the 12V and 24V battery Cables.

Thanks For Looking

Have you gone through the flow chart from Niehoff? They have a stern by step to check the alt. Maybe it's the voltage regulator?
The ground strap from the alt to the frame is good?

 

[Alexandninasdad]

Have you gone through the flow chart from Niehoff? They have a stern by step to check the alt. Maybe it's the voltage regulator?
The ground strap from the alt to the frame is good?

 

[Alexandninasdad]

Checked Alternator ground for continuity = A OK
Checked the smaller wire that is also connected to the ground and did not get continuity .... where is that small wire connecting to ?

I started the engine and had it running. Removed both wires from the Regulator. Plus the small wire from the ground and took readings from the large studs
24V jumper to PDP readings No change at all.
Red 12.5 Yellow 24.66 with jumper connected identical when disconnected. So DOA ???
My guess is that the smaller wire to the 24V stud is connecting the Voltage Gauge. (???)
I will try to read the tiny metal tags on the wires next.
I see TL 110. TL 35. TL 5 (?)
Verified Ground in the plug going to the regulator = A OK

 

[Alexandninasdad]

I’m getting 24V at the Yellow terminal in front and 12v at the Red one in the back. Is it possible it’s as simple as swapping those large cables over ?

 

[Alexandninasdad]

I’m getting 24V at the Yellow terminal in front and 12v at the Red one in the back. Is it possible it’s as simple as swapping those large cables over ?

YES it absolutely is just that easy. 14+ and 27+ And climbing. Maybe those motor pool bayous thought they would have some fun with whoever picks this one out of the lineup.

 

[Alexandninasdad]

IN CONCLUSION : Thanks to everyones' great pointers charging issue is now resolved. The biggest issue was finding someone with enough grey hair and patience / experience to actually test and assess my Alternator. Three different ( Big Name and highly Recognized ) Electric shops bench tested and returned incorrect diagnoses. Finally I ran across someone that actually called Niehoff TO ASK the proper way to bench test. ( Genious !! ) .

After having wasted a great deal of time gas and money it turns out the original Alt was fine. The cables were switched 14/28 and ergo safe mode = no charge. I DID check all of the cables connections etc. but ASSUMED that the truck was set up " right " to begin with.

So my mental starting point from here on out... in the Thirty years that this machine has existed there have clearly been a LOOOONG Parade of IDiots , Fu#k-tards and newbies that have wrenched on it to fix one thing while damaging another.

Along the line I also swapped out the Voltage gauge with a digital one ... there was green snot on the posts of the old one. Im guessing green snot is more of an insulator than conductor. Also it took time to make sense of the battery box setup, now i know exactly which posts to check for 14/28v.