"Charging System" warning light

[Scott z]

2003 M1078 a1. I've searched threads with no luck and my first generation m1078 manual does not address this warning light.

The light stays illuminated prior to starting when electrical is on and while driving.

I assumed alternator however the battery voltage indicator has remained constant at around 13 and 26 volts during a fairly active day of driving.

Anyone know what this light is related to and if it's likely to leave me stranded without further notice?

Thanks

Scott

 

[DOUBLE ALT]

Scott
The light is most likely triggered by the regulator. Check voltage with a good voltmeter at the batteries.
Fully Charged lead acid good battery will read 12.6 volts with all power turned off and engine NOT running.
Check each battery. Check your automobile 1st to see how it performs.
With engine running at a fast idle, you should see 13.6 to 14.8 volts. Turn on lights, radios, etc. to see if alternator can keep up with load. Voltage should only drop about .5 volt, but not below 13.6 volts. That means the alternator is ok.
I believe you have a voltmeter that reads the 24 volt system and it should read 2 times the 12 volt meaning
25.2 volts no load and engine off. Fast idle 27.0 to 29.0 volts and then with a load 27.0 to 28.5
What is the alternator Model number.
ron@double-alt.com

 

[Scott z]

Thanks. 76761-N1509-1
Part#19207SOCN12422863

The light remained on for most of the day yesterday. Started her up this morning and the light was iff while I idled for about 3 mins.

 

[DOUBLE ALT]

Scott; That alternator has a record of failures as stated on several threads. The mounting bracket has a issue as well. It is a 28 volt alternator with a maximum output of 100 amps. It converts the 28 volts to 14 volts using SCR's/diodes. You only have one 28 volt gauge. If the 28 volt side fails you loose the 14 volt side too. If you add extra load to 14 volt side, it takes away power/watts from the 28 volts causing failure. You need the 28 volts for the transmission and engine controls.
You can visit my add on classified section for replacement alternators. Ours are true double voltage separate outputs.
The light is not the issue, the voltage output is the real condition of the alternator. Buy two digital 14/28 volt gauges.
regards RON

 

[porkysplace]

Scott; That alternator has a record of failures as stated on several threads. The mounting bracket has a issue as well. It is a 28 volt alternator with a maximum output of 100 amps. It converts the 28 volts to 14 volts using SCR's/diodes. You only have one 28 volt gauge. If the 28 volt side fails you loose the 14 volt side too. If you add extra load to 14 volt side, it takes away power/watts from the 28 volts causing failure. You need the 28 volts for the transmission and engine controls.
You can visit my add on classified section for replacement alternators. Ours are true double voltage separate outputs.
The light is not the issue, the voltage output is the real condition of the alternator. Buy two digital 14/28 volt gauges.
regards RON

The biggest failure of the mounting bracket and bolt is related to bad driveshafts shaking the driveline apart . There is nothing wrong with surplus alternators . $1500 for a alternator is more tan most people here are going to spend.

 

[Suprman]

See if your truck has the advanced polarity protection box. It will be under the spare tire. This interacts with the alt regulator and regulates battery charging. Sometimes this box starts going bad causing issues like you are having. The double alt thing is not compatible with your truck if you have this type of box.

 

[DOUBLE ALT]

Drive shafts and tire balance do not effect the alternator.
The alternator bracket failure is two fold. The bottom long bolt is the wrong size, being smaller than the bracket allowing it to shake.
The top bolt is even smaller than the bottom bolt, and connected to a 90 degree bent bracket.
Why is it that other bolt on engine parts don't fall off or break the brackets holding them on? I did my homework and went to 2 local armory locations and they have the alts falling off too. They have new tires and new driveshafts.

It would be better to remove the controls, and have less chance of a electrical problem. 17.5 million US cars built in 2016, and all without these controls. Hundreds of millions of autos and other vehicles without those controls. They go 200,000 miles and no failures. Hello
As to price, a New Niehoff is a lot higher when you can find one. We use only New modern parts with 2 year warranty, and made more durable.
Our alt works, even with all the extra controls. Several LMTV owners have our alts. A harder job, some have added a 2nd alt.
Keep checking with meter or better still add two gauges. I have them if you can not locate on your own. The lite is or is not very helpful on the condition of electrical system. At least you noticed it.

 

[Suprman]

On the a1 with advanced charging and the battery cutoff solenoids you want to keep the original system in place. Theres a reason for the whole setup. Unplug the mil connector from the box under the spare tire see what happens. And check all your batt connections make sure everything is clean and tight.

 

[Scott z]

So I don't see anything resembling an advanced charging box or electronics under the spare but will check battery connections etc.

 

[Suprman]

Do you have batt cutoff relays in or next to the battery box?

 

[Scott z]

Yes I do.

 

[Suprman]

Then you have the adv charging box.

 

[mechanicjim]

here are the links to the Troubleshooting guides for the N1509 and N2003
your voltage numbers are low, also try checking the voltage of each battery individually to make sure one isn't pulling the rest down.
http://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG0014D_uid12172009224052.pdf
http://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG53B_uid1252012258102.pdf