BATTERY DISCONN dash warning light

[hike]

Point me in the right direction please. I have spent too much time in the TM's looking for this and must just be too stupid or unable to channel the right mindset to find what I am seeking.

2003 M1078A1 has the red dash warning light BATTERY DISCONN lit, though everything (except the bricked CTIS) appears to be working correctly. She starts, she runs, the alternator recharges, lights in and out work. I have checked the fuses/relays, though all the small green lights in the panel aren't lit, again everything I have seems to be working.

Other than the fact that it bothers me and I am awaiting that moment the starter doesn't rotate and engage, she seems fine; and I haven't found the right place to learn where to start looking.

If you can point me toward a TM or have a suggestion I appreciate your time–

 

[Ronmar]

The battery disconnect light is controlled by the state of the disconnect relay in the box to the rear of the battery box… since all the 12 and 24v power passes thru it, if you are operating normally, it is obviouslay not disconnected, but that is where the idiot light is controlled from…

 

[hike]

Thank you. I'll start there—

 

[Keith Knight]

I had that problem with my 2003, if you open up the box ronmar mentioned you will find an electronic device inside causing the problem. When I was looking for it 7 years ago it was $700 new. I found someone parting a truck out and purchased it used for less than $100. But it fixed the stupid light.

 

[GeneralDisorder]

There's a new versions of the disconnect relay. It's totally enclosed and much more reliable. Bussmann makes them now:

Sure Power 3106 Battery Disconnect

3106 Battery Disconnect, Sure Power Manufactured using the best quality from sure power, 1 year warranty.

www.ase-supply.com

The original one's have multiple problems. If you have the original with all the individual wires pitch it - you will end up bypassing it someday to get home.

 

[Ronmar]

If you drop to two batteries, you can get rid of it entirely. The main purpose of that relay and the LBCD that controls it, was to disconnect a faulty battery from the alternator when it fails, to keep it from damaging the alternator and allowing you to continue the mission.

if you properly size the battery for the truck/alternator, that relay becomes unnecessary. I have never seen anything like this system on any vehicle I have ever worked on… Weird shit happens in the world of milspec.

 

[hike]

Further exploration leads to finding the LBCD disconnected. Connecting adds the CHARGING SYSTEM dash warning to the BATTERY DISCONN dash warning. Shoot. Alternator still charging, starter still engaging. So far everything I use works, even the CTIS when the connections are jury-rigged.

The battery disconnect looks like I do at 62, not how I did at 20; ordered the 3106 battery disconnect. Any chance that will fix both warnings? (The new guy has to ask, right?)—

 

[NotThatGuy]

The battery disconnect looks like I do at 62, not how I did at 20—

They say that 60 is the new 30.....I wish they'd tell all my Orthopedic-Systems that.

 

[Ronmar]

Further exploration leads to finding the LBCD disconnected. Connecting adds the CHARGING SYSTEM dash warning to the BATTERY DISCONN dash warning. Shoot. Alternator still charging, starter still engaging. So far everything I use works, even the CTIS when the connections are jury-rigged.

The battery disconnect looks like I do at 62, not how I did at 20; ordered the 3106 battery disconnect. Any chance that will fix both warnings? (The new guy has to ask, right?)—

The LBCD controls that charging system trouble light. It is looking for an acceptable voltage when it sees the alternator over 1500RPM. greater than 24.5V if I am reading the Neihoff manual correctly. If it drops to 20.5v it disconnects the battery and puts it on a trickle charge. If your voltages are above 24.5v at the alternator I suspect your LBCD has failed…

you can download the N1509 / N1511 Alternators and N2003 LBCD Troubleshooting Guide from the Neihoff website…

 

[hike]

The LBCD controls that charging system trouble light. It is looking for an acceptable voltage when it sees the alternator over 1500RPM. greater than 24.5V if I am reading the Neihoff manual correctly. If it drops to 20.5v it disconnects the battery and puts it on a trickle charge. If your voltages are above 24.5v at the alternator I suspect your LBCD has failed…

you can download the N1509 / N1511 Alternators and N2003 LBCD Troubleshooting Guide from the Neihoff website…

hmmm. I haven't checked at the alternator; dash gauge is higher, CTIS H and M are higher. Sounds like more good news =/

All good, it is all good. Better to know and address, than being clueless on the road once it comes up. Thank you, I appreciate all you share here on the forum—

 

[Ronmar]

Like I said earlier, if the batteries are properly matched to the alt. 2 batts instead of 4, 100-120AH wet cell battery bank, the LBCD and the disconnect relay becomes unnecessary...

 

[hike]

So, while still awaiting the relay's arrival, @GeneralDisorder suggested, I am looking for a rattle likely from the cab latch alignment. While working on that I noticed the lights upon the alternator flashing in an alternating fashion: 24v, 12v, 24v,... I assume that is good.

Still left is the question of why the cab latch adjustment is found in hydraulics, (though the adjustment is actually just alignment of the latch and catch, no hydraulics in the task list)?

 

[GeneralDisorder]

Flashing green on the voltage regulator is good.

 

[hike]

With the BATTERY DISCONN and CHARGING SYSTEM warning lights on we are running through the ¿PDP? on the cab passenger side dash. I need to order some micro- and mini-relays, clean up the board and perhaps some electrical lube.



Good news is after pulling cleaning and reseating a number of the existing relays the CHARGING SYSTEM light is off.

Any suggestions for relay sources are welcome; I didn't see them on the pinned frequent parts list—

 

[Ronmar]

What color were they flashing? They should be flashing green? The alt is a standlone device, the LBCD simply monitors its RPM and voltage output and commands the disconnect relay or lights the charge trouble light…

yea the cab latch adjustment is mechanical, usually with the vertical position of the bracket or the spacer stack between cab side of the latch assembly and the bracket bolted to the back of the cab. You want to position the upper latch plate and the cab bracket so the cab guide plates on either side of the rear tunnel opening, set firmly down onto the guide pins on either side of the arch… when the latch bottoms out to early the guide plates will rattle and squeak on the pins. Latch bottoming out too late and the upper latch itself can rattle between lower latch and bracket…

 

[Ronmar]

Isopropyl alcohol and a 1” paintbrush for the board cleaning. Disconnect the batteries first and until the board is completely dry

Sounds like perhaps the alt excite relay(K11) was not feeding proper voltage to bring the alt online. It needs at least 22v at the excite terminal(front terminal on the regulator).

The A1 is easy, it only uses 12v coil relays(A0,needs 12 and 24v coils), so standard 5 pin automotive relays will work anywhere, found at any auto parts store…

 

[hike]

What color were they flashing? They should be flashing green? The alt is a standlone device, the LBCD simply monitors its RPM and voltage output and commands the disconnect relay or lights the charge trouble light…

Green—

 

[hike]

Isopropyl alcohol and a 1” paintbrush for the board cleaning. Disconnect the batteries first and until the board is completely dry

Sounds like perhaps the alt excite relay(K11) was not feeding proper voltage to bring the alt online. It needs at least 22v at the excite terminal(front terminal on the regulator).

The A1 is easy, it only uses 12v coil relays(A0,needs 12 and 24v coils), so standard 5 pin automotive relays will work anywhere, found at any auto parts store…

Added to my list—

 

[GeneralDisorder]

If you really want it CLEAN then you remove it and wash it in soap and water with a soft brush then allow to dry in the sun. Apply Deoxit to the connections. Anything thick like dielectric grease will just trap dirt.

After the cleaning inspect all the solder joints with high powered magnification. Any that are showing signs of problems should be addressed. Ideally with solder that has actual lead in it not the lead free crap.

 

[hike]

If you really want it CLEAN then you remove it and wash it in soap and water with a soft brush then allow to dry in the sun. Apply Deoxit to the connections. Anything thick like dielectric grease will just trap dirt.

After the cleaning inspect all the solder joints with high powered magnification. Any that are showing signs of problems should be addressed. Ideally with solder that has actual lead in it not the lead free crap.

Good to know. With my old eyes I need magnification to read the newspaper—