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2008 LTMV goes into over charge dash shuts off
- Thread starter MGVFD
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Ronmar
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Voltage regulator is solid state, so what exactly was clicking?
Its a 2008, does it have a green circuit board type power panel, or does it have 4 PDM boxes?
both A1s are wired the same IRT the lighting, battery 12 to CB70 to pin F on PX15 of the lightswitch. When EXACTLY does CB70 pop?
Its a 2008, does it have a green circuit board type power panel, or does it have 4 PDM boxes?
both A1s are wired the same IRT the lighting, battery 12 to CB70 to pin F on PX15 of the lightswitch. When EXACTLY does CB70 pop?
CB70 pops immediately. I can reset and it pops. The clicking is what I think is a voltage regulator. It is by the main battery cut off.
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Ronmar
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OK, that device you pictured is the remote battery disconnect relay module. it is controlled by the LBCD, or a manual switch below the drivers dash(red guard switch cover). The LBCD monitors the alternator output and disconnects failed batteries from the alternator if the alt appears overloaded. it should light a batt disconnect light in the dash when that relay opens/disconnects the batteries. the LBCD and this relay was a band aid to help save the undersized alt. from the oversized battery bank when it overloads the alt. if you have new batts, I would disconnect the control cable from the LBCD until you can evaluate what exactly is going on, as it shouldn't activate until the alt passes 1500 RPM. You can access the LBCD module by lowering the spare tire and unplug the cannon plug on the module. If it still clicks, you can unplug the control lead on that relay module itself...
Well if CB70 pops immediately, you need to lift the dash and unplug PX-15 on the back of the light switch and try it again. if it still pops CB70, the wire between CB70 and the light switch plug is shorted to ground. if it does not pop, the light switch may be bad. I know the pushbutton switch assemblies are sensitive to having a good ground, so you need to make sure its ground wire is properly making contact with chassis ground. They also fail far more frequently than the older 3 lever switches do
Well if CB70 pops immediately, you need to lift the dash and unplug PX-15 on the back of the light switch and try it again. if it still pops CB70, the wire between CB70 and the light switch plug is shorted to ground. if it does not pop, the light switch may be bad. I know the pushbutton switch assemblies are sensitive to having a good ground, so you need to make sure its ground wire is properly making contact with chassis ground. They also fail far more frequently than the older 3 lever switches do
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In medicine, LBCD apparently stands for Lateral Border of Cardiac Dullness.
I find that really amusing and particularly appropriate.
I find that really amusing and particularly appropriate.
Ronmar
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Load battery charge dissconnect i think... or is it control disconnect? Its a polarity protection devjce with a very small pea brain and a large capacitor bank to catch the inevitable voltage spike when you disconnect the load from an overloaded generator...
coachgeo
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potato / potaato - but sorta notto- cause it identifies a feature...... is it not more so:
Load BALANCE control (or charge) device (or disconnect)?
If LBCD does not do any "balancing" between the 12v banks then obviously not. Was under the impression it did.
mechanicjim
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N2003 Load and Battery Control Device (LBCD)
see above for name and simple wiring explanation
see above for name and simple wiring explanation
Ronmar
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Load and battery control DEVICE… No balancing whatsoever… it is a Polarity Protection Device(PPD) like used on the A0 trucks, with 2 added circuits. One circuit monitors alternator RPM(AC signal from reg) and 28v output. If the alt goes over 1500RPM but not over 20.5, it sends a signal to that relay to disconnect the batts. it can also send a signal to the dash to light the charge trouble indicator.
the second circuit is a capacitor bank/filter that I believe is designed to try and blunt the voltage spike that is created by the loaded alternator(full excitation) when you disconnect the thing that stabilized it(battery), until the regulator can reign it in and collapse the field… Disconnecting the battery from a loaded alt is considered poor form just about everywhere in the world, and this is the most asinine circuit I have ever encountered on a motor vehicle…
the second circuit is a capacitor bank/filter that I believe is designed to try and blunt the voltage spike that is created by the loaded alternator(full excitation) when you disconnect the thing that stabilized it(battery), until the regulator can reign it in and collapse the field… Disconnecting the battery from a loaded alt is considered poor form just about everywhere in the world, and this is the most asinine circuit I have ever encountered on a motor vehicle…
coachgeo
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thanks for clarification Jim and @Ronmar
coachgeo
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you can re-wire to a standard light switch. Otherwise ebay... but only get one of that particularly military type that shows a ground screw on back. The non ground screw ones..... seemed to cause fires.. not a good thing.
PS- unlike the past... our FMTV's are 12v lights... NOT 24v
InvictusDecretum
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I had this fun thing where my troop alarm went off for ~3hrs of driving before I figured it out. Which was odd, since not only did I not have any troops in the back, I also disconnected the switch. Turns out the metal tag had chafed through the insulation and was shorting the wires together. Might be worth following the wires to the lights from CB70 and seeing if there is also a metal tag on bare insulation, and not the heatshrink.
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It was the Spirit of fallen hero's reminding us maintain our stuff
Not sure if this deserves another thread. Our Fire dept has been awarded another M1078A1. It is a 2003 four wheel 2.5 ton. It is coming to us with issues from the forestry service. I will attach the inspection sheet given to us. We have not received the unit yet. I have attached the review doc. I have read other post/threads, but can the lcbd be deleted with the two battery setup? That is the biggest ticket item listed so far. Thanks
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I think @Ronmar addressed this in post#8 in this very thread sometime back? Reread paragraphs 1 and 4 in Post#8.
Where in Texas are you all?
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LBCD. Lateral Border of Cardiac Dullness. 
(I felt like saying it again, it's been a long week.)
(I felt like saying it again, it's been a long week.)
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Well I guess a special. I am not a mechanic not am I paid. I work on this truck when time permits to help the station. So I read some of these thread and it is still clear as mud. If my post offend you or anyone else sorry. I am trying to figure this out so we can get these trucks back on the road. I reread the threads. I am not sure if you can delete the lcbd with a two battery setup? Our station doesn't have a big budget so if I can save it $700 then that is a win. We have to get batteries regardless. Most likely the ones in it are out of date.
Thank you for your patience.