Oh hey so here’s the situation, went to start the motorhome today and no crank. Tried to fire generator using the boost switch no crank. Went back to the house battery compartment and used a pair of jumper cables and two new batteries that I had fired the generator off. It ran for about 15 minutes when I tried to crank the engine it would shut off the generator this happened two times then the generator would not start again just clicking. Changed out both starting batteries with new thousand 88 cold cranking amp batteries all load tested good and show 13.5 V. Trying to crank generator and all I will get is a clicking noise (like dead battery) pulled terminals off cleaned and checked nuts nice and tight no issues. Kind of stumped where I should go from here have to have something that shorted or zapped a relay a big boy a bird something like that I can only imagine just don’t know where to look. I have a multimeter if anyone can walk me through what to check I would greatly appreciate it.
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Wow, great coach! Now you just need to fix some things to make it enjoyable.
In the rear electrical run box (on the right side of the engine) is a large Intellitec solenoid called the Big Boy. It's used to connect the house and chassis batteries as well as the Boost function.
You need to remove it and clean the contacts, or just replace it. Be careful as there is enough amperage back there to arc weld. Once it's working correctly your Boost function will work and it will keep the chassis batteries charged when plugged in. Instructions are attached courtesy of Mike Canter.
If you decide to purchase a new Intellitec Big Boy I found one on eBay and then rebuilt the old one to keep as a spare.
The next thing is a gear reduction starter. It will crank faster and with less effort if you change out the OEM starter and add a Delco gear reduction starter. It's really not a tough job and they are fairly reasonable.
Link to gear reduction starter thread: https://www.irv2.com/forums/f123/isx...rt-366504.html
Good luck with your coach!
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97 Monaco Windsor- Sold
07 Monaco Executive McKinley- Sold
04 Monaco Signature Chateau IV
OK this was one of my questions, would the big boy failing cause the rig not to start with brand new coach batteries in it. I’ve installed new batteries at this point in the last few hours and still getting clicking noises at my generator and lights intermittently flashing on the dash no crank
Hi Golden by; Not the expert here but, I think this is what happened. Running the gen. for just 15 minutes would no way charge the chassis batteries if they were dead. Batteries could have been so far dead that they might have not even been taking a charge. When you went to crank the engine it lowered the voltage far enough to shut down the generator. As with many Monaco or Holiday Rambler coaches, not sure if your gen. gets its power from the chassis batteries or the house batteries as you mentioned you used the boost switch to get the gen. to start. Can you get your gen. to extend on the slide as I am sure on your level of coach the gen. slide is battery powered. If so, or depending if you like sliding around on your back, I would check the voltage at the 2 terminals on the back of the generator. This will tell you what voltage you have at those terminals. I have seen others use a good battery and jump right to the terminals at the back of the generator to get it started. Sounds to me like there is still some weak batteries in the system. See if you can isolate what set of batteries start the gen, chassis or house, and go from there.
I know you have a big engine in your coach and it's going to take fully charged batteries to turn the engine over. If you manage to get the gen. started I would use your volt meter to see if you are charging the chassis and or the house batteries. I am sure one set has a priority over the other for charging. Hope this gets your started.
Hi Golden by; Not the expert here but, I think this is what happened. Running the gen. for just 15 minutes would no way charge the chassis batteries if they were dead. Batteries could have been so far dead that they might have not even been taking a charge. When you went to crank the engine it lowered the voltage far enough to shut down the generator. As with many Monaco or Holiday Rambler coaches, not sure if your gen. gets its power from the chassis batteries or the house batteries as you mentioned you used the boost switch to get the gen. to start. Can you get your gen. to extend on the slide as I am sure on your level of coach the gen. slide is battery powered. If so, or depending if you like sliding around on your back, I would check the voltage at the 2 terminals on the back of the generator. This will tell you what voltage you have at those terminals. I have seen others use a good battery and jump right to the terminals at the back of the generator to get it started. Sounds to me like there is still some weak batteries in the system. See if you can isolate what set of batteries start the gen, chassis or house, and go from there.
I know you have a big engine in your coach and it's going to take fully charged batteries to turn the engine over. If you manage to get the gen. started I would use your volt meter to see if you are charging the chassis and or the house batteries. I am sure one set has a priority over the other for charging. Hope this gets your started.
My intentions were in the morning to air up my bags using an external compressor slide under the RV at that point and be able to tell what voltage I’m getting at the back of the generator. The coach is plugged in and as I stated before the coach batteries are brand new 8d two of them and for 200 amp power Lithium batteries for my house batteries so I’m thinking somewhere I’m losing the voltage I just don’t know where to start looking. I plan on tomorrow getting the coach up in the air and then being able to see what I’m getting at the back of the generator
You can measure the voltage at the generator without airing up the coach. Just extend the generator slide. However, measuring voltage at rest is not that useful. I would want voltage when cranking the generator.
The generator shutting down when cranking the coach engine is not unusual. If your chassis batteries are low, then when you crank the big engine, it lowers the voltage to the generator fuel pump enough that it shuts down the generator.
Also, 8D batteries are some of the worst available for a motorhome (my opinion). They work fine in a class 8 semi-truck because they are always running. Motorhome batteries are sitting most of the time. Next time get two quality Group 31 batteries for the chassis. Your back will thank you and they will last twice as long and crank better.
Now, your 200-amp hour lithium house batteries. Depending on what type of camping that's probably not enough. On top of that lithium batteries are not good cranking batteries. They do not withstand large discharges like cranking a generator or engine.
Check your battery grounds where they attach to the chassis. Then check voltage at both sides of the Big Boy while plugged into a 50 amp service. Then have someone depress and hold the Boost switch while you listen to the Big Boy. It should make a loud click. It should also be warm/hot after the coach has been plugged in for a while.
Make sure your Magnum inverter is on and the charge option is selected.
How do you plan on isolating your lithium batteries from the alternator? You may be okay for a short period but if you discharge the house batteries and start the engine it may overheat your alternator.
I guess I've written enough for tonight. Good luck!
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97 Monaco Windsor- Sold
07 Monaco Executive McKinley- Sold
04 Monaco Signature Chateau IV
Good evening Golden by; Sounds like you have a plan. Looks like you have some power from your 8D batteries. If you have a helper while your at the terminals on the back of the gen. you could have them, one at a time, switch the battery disconnects to the off position and see what set of batteries are suppling power to the generator. This could help isolate problem. Others here are experts on the Big Boy. I do not have one of those on my 01 Windsor, just a boost solenoid to connect the chassis and house batteries in case of low batteries to start the generator. Was instructed years ago that if the engine will not crank, get the gen. started and let it start charging the batteries. It can take a while but its better than depleting more amperage that it takes to start the engine.
Once you get the gen. started you can see what batteries are getting charged as long as your Big Boy solenoid is working properly. As you stated you have the coach plugged into shore power. Before you start you project on checking the voltage at the back of the generator you might want to take your voltage meter and check both sets of batteries to see if either set is charging off the inverter. Will give you some idea of what is happening if you are not getting any charging to either one set or both sets of batteries. Wish you good luck on your search tomorrow. After posting read Vito .a post. He has given excellent advice along with the trouble shooting of the Big Boy.
It might help you track down the path of the power to the generator.
In my case my generator is powered from the house batteries. The (+) wire is attached directly to domestic battery stud which in my case is my passenger side rear electrical bay.
You consider getting a wire tracer which would tell you where it might be in your wiring circuit. Attach the tone generator to the (+) stud on the generator and look for a signal in your rear run bay.
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Jim J
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi
I would say you are under-batteried for sure, plus your Big Boy isn't working properly. When I had my coach, I had 8 Lifeline AGM batteries for the house and two for the chassis. Before I switched the batteries out, I had the same problem trying to start the truck and kill the generator. Also, when my bird was bad, it would not charge the chassis while plugged in, but would charge the house and driving the coach the alternator would charge the chassis, but not the house. My coach had the 525 ISX Cummins and switching out the starter like Vito said is a must! Hardly would spin over with the original starter, once changed the motor almost jumped out of the back end when it spun over
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Randy & Kathy-n-Auggie
07 HR Navigator 43PBQ, 525hp Cummins ISX, 17 Ford Supercrew Ecoboost King Ranch 4x4
The big boy can work fine and still not pass current through the contacts. The blue seas acr with the dash switch is a much better option than fixing or replacing the big boy. Gets the bird out of the system too as the acr is all in house and lifetime guarantee. No more humming sound in the bedroom at night either. And as said start cleaning your grounds.
You can measure the voltage at the generator without airing up the coach. Just extend the generator slide. However, measuring voltage at rest is not that useful. I would want voltage when cranking the generator.
The generator shutting down when cranking the coach engine is not unusual. If your chassis batteries are low, then when you crank the big engine, it lowers the voltage to the generator fuel pump enough that it shuts down the generator.
Also, 8D batteries are some of the worst available for a motorhome (my opinion). They work fine in a class 8 semi-truck because they are always running. Motorhome batteries are sitting most of the time. Next time get two quality Group 31 batteries for the chassis. Your back will thank you and they will last twice as long and crank better.
Now, your 200-amp hour lithium house batteries. Depending on what type of camping that's probably not enough. On top of that lithium batteries are not good cranking batteries. They do not withstand large discharges like cranking a generator or engine.
Check your battery grounds where they attach to the chassis. Then check voltage at both sides of the Big Boy while plugged into a 50 amp service. Then have someone depress and hold the Boost switch while you listen to the Big Boy. It should make a loud click. It should also be warm/hot after the coach has been plugged in for a while.
Make sure your Magnum inverter is on and the charge option is selected.
How do you plan on isolating your lithium batteries from the alternator? You may be okay for a short period but if you discharge the house batteries and start the engine it may overheat your alternator.
I guess I've written enough for tonight. Good luck!
OK so here’s a question for you, So went out today and bought three group 31 950 cold cranking amp batteries, all new cable installed all three batteries with new cable . Try the ignition and the same thing lights flickered on the dash no crank. I was told by someone else on another one of the sites that I’m on that I could jump her across the big boy and start my generator that way. So the two large lugs I jump across like jumping a car solenoid and generator fired perfectly. So just curiously I crank the engine and that also fired perfectly. So I’m assuming my problem is with my big boy ? Once the coach was running I hit the power slide button for my generator to slide it out and immediately killed the coach. Jumped across the big boy again and then immediately refired battery showing 13.8 V no excessive charging anywhere. So is everything run through the big boy could the big boy truly be not allowing current to pass through unless it’s jumped manually?
Big boy is a battery combiner for charging house batts off of alternator and or chassis batt from shore power plus jump/ boost via switch at dash. If new chassis batts didn't start it but boosting/jumping around big boy did ,could be chassis cables, manual disconnect, main chassis battery frame ground. The house batts using their ground getting it started.
Please clarify new batts are chassis start or house deep cells .
Big boy is a battery combiner for charging house batts off of alternator and or chassis batt from shore power plus jump/ boost via switch at dash. If new chassis batts didn't start it but boosting/jumping around big boy did ,could be chassis cables, manual disconnect, main chassis battery frame ground. The house batts using their ground getting it started.
Please clarify new batts are chassis start or house deep cells .
Simple, to the point and spot on.
You seem to have at least two problems. The Big Boy is not functioning, and you have a problem getting power from your engine batteries to the proper location/s. That is just as said in quote.
Follow your engine battery ground/negative wire. Take it off everywhere you find a connection, then clean and retighten. Make a mental note of any connections that were easy to disconnect.
If that does not cure your "second problem", do the same with the positive leads. (You should do this in any case.) There have been plenty of bad battery cutoff switches reported over the years.
Your "first problem", as discussed in previous responses is the solenoid not working or the system that turns it on. Your temporary bypass jumper proves that.
I suspect there is a purple wire, (electrons are color blind), on one of the small terminals. In any case, once the generator is running or shoreline connected and after a couple minute delay there should be voltage on one of the small terminals and a ground on the other small terminal.
If you do not get the power to turn the solenoid on then that can be easily chased down.
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Certified Senior Electronic Technician, Telecommunications Engineer, Telecommunications repair Service Center Owner, Original owner HR 2008
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