battery repl, now wont start

[RonS]

Hello,
I replaced my chassis battery now MH won't start without using boost switch. No instrument lights & no engine crank.
Checked voltage at battery, all fuses in battery compartment, followed hot wire from battery to starter and have power, fuses under dash/engine compartment/external electrical panel/coverter fuses & replaced chassis relay switch behind exterior electric fuse panel.
Any other ideas?

[Morich]

Each time we make a change or work on things, we add one more element of possibly making a mistake! So my first thought would be to stop making any more potential trouble spots!
When you changed out the battery and found no power to the starter, that would have been the ideal time to check what you had done for anything that you might spot.
Did you check the new battery for it being good?
The problem is that there are several different power systems and they connect and disconnect at differet times for doing different things, so we have to think carefully before we go too far.
One of the big things on motorhomes is that the starting system is pretty much disconnected from the coach 12 volt except two times. One is when we push the boost switch and the second is when we turn the ignition key on.

To really begin to help, we will need more really specific info. starting with which RV you have. Age and model or type of chassis are going to be big items to know as ignition and starting systems vary so much from older to newer and gas to diesel.
So what are you working on?

Then I might start back at the start and work the question as if it were just another car or truck. The starting system is just like a normal truck as it is built on a stripped truck chassis but that makes them vary as much as the trucks on the road vary!

This is less of an RV question as it is a truck starting question, so it may take some looking at truck chassis info to get down to how your specific "truck" starts.

Start by telling us what truck you have, perhaps?

As a general thought that fits many different RV, it sounds like there is a problem of getting the start battery power to the starter solenoid. Since you seem to say that it starts when the boost switch is pushed, that shows much of the system works when the boost switch connects the coach battery together with the start battery.
That often means the start battery is dead or not connected if things work when a different battery is connected.

But we need far more speciifc info.

[Morich]

WHOOPS! Scratch all that complaint about not knowing which RV! I was not looking att that right place to get that info! SORRY!

So that means I need to rethink the whole idea!

The start battery seems to not be doing what it should. If I read correctly, the RV start when the boost switch is pushed but nothing when the start battery has to do the job. If it start when the two batteries are connected together, it says most of the starting system works, just not the battery!

So how have you checked the new battery? Are you sure it is good and wired correctly?

[RonS]

I have a F53 Ford chasis V 10 gas engine. I checked the battery with a volt meter to make sure it was good along with all connections. I called Winnebago and they recommended replacing the relay, which I did, but it still didn't work. I then started looking on forums and checked more breakers and relays without replacing any more. Still no luck.
I plan to take the battery in for a load test. Not sure what else it can be unless there's another hidden relay or breaker.
Wish me luck or please give me any info you may know. Thanks so much.

[Morich]

Ok, sorry about missing the info. Careless looking!

There may be some points that don't show easy that we miss. I had a 2015 vista 31KE and found a problem at a big "mega fuse" out just behind the front pass. wheel.
This drawing for your Rv has some info that should show the path of the start battery and may help. I marked what I think will be the path from the battery positive to the relay and back past the relay as being numbered 1-4.

But then the drawing gets into what look like a mistake in drawing things!!

What I think you will find is that the start battery and wiring has a spot of corrosion/dirt keeping the battery power from reaching the starter solenoid. But since it starts when the boost switch is pressed, that says the starter solenoid and most of the smaller wiring is good, just that the boost switch adds a second path for the coach battery to reach the starter.

I took this snip from this drawing and you might check if it looks right or not. One trick to make sure we are not walking past a dirty spot is to first read the voltage on the post and then read it at the cable connected to that post. Connected together they should be the same, so if you get a 1/2 volt or more difference, check for corrosion!
I think what I see is it goes 1,2,3, 4 but what you see is more imortant than what I'm guessing at being true.
Don't forget to check for good ground for the chassis battery also!

Click this snip from this drawing or go direct?
https://www.winnebago.com/Files/File...ire_183487.pdf



Note the colors, red and pur (purple) on the drawing as that should have tape on the cables to help ID going to the disconnect and coming back! A way to check the relay is find no voltage coming back when disconnect is open but voltage there when disconnect is closed! Verify disconnect is working?

I read this as saying the power goes from start battery at 3, to the disconnect relay and back to 4 at the isolated stud. They use "isolated stud" as being a bolt on the frame that doesn't actually connected but is isolated from the frame. Just a point to connect two cables together without grounding to the frame?

This is the drawing for where coach and start bat get connected together.
https://www.winnebago.com/Files/File...ire_183488.pdf

But there are two versions of your RV as they changed from a solenoid to a BIM system.
Maybe look at what you have to spot which? You may be able to spot which by peaking in over/under all the breaker panel? the solenoid is a pretty large, heavy duty solenoid, while the BIM is an enclosed electronic gizmo which is hareder to guess at what it does!
I suspect you will have the BIM if you have a chassis battery disconnect.
Sheet 4, older simple or sheet 2 which is more complex?

Serial number with 7th digit of 1 for older and 7th digit of 2 is newer?
May help to assure I'm looking at corrrect drawing!

But I really suspect the problem is more like just corrosion at some connection along the cables from start bat to starter , and they can hide them in odd places. Put a cover over it and add some road oil and it hides really easy but it's a good place to corrode!
https://shop.pkys.com/Blue-Sea-5001-...8aAs-pEALw_wcB

Hope this will help sort the problem! Good luck.

[Ray,IN]

If the MH started before replacing the start battery, but now does not start, the logical conclusion is incorrect installation. Did you take a picture of the battery and wiring before removing anything?


Have you tested each connection in sequence from the battery to the starter? If yes, where is the last hot connection?

[Morich]

Originally Posted by Ray,IN

If the MH started before replacing the start battery, but now does not start, the logical conclusion is incorrect installation. Did you take a picture of the battery and wiring before removing anything?


Have you tested each connection in sequence from the battery to the starter? If yes, where is the last hot connection?

Fully agree with this but since it is a single battery for the chassis starting and it does start when the boost switch is pushed, I moved away from it being installed backwards as the two are connected toegher at that time. Thinking that connecting two batteries together backwards would let us know it right away!!
That led me to think corrosion making the chassis battery open along the route.
The 1,2,3, numbering seems to be the route as it leaves the battery compartment, goes to the battery disconnect and then forward to the starter, so, thinking that path has to have a fault??

An easy one is leaving the ground cable loose at one end or the other!

But we never know at times what was found??/

[eyecando]

Most likely the cause is corrosion or a loose connection at the battery terminals. Remove the chassis battery terminals and make sure there is no corrosion present inside the terminals and scrape it off if there is. If the battery terminals have been replaced with after market terminals, corrosion could be present where the cable lands. Or could be a bad ground connection at the chassis negative battery wire. Always remove the negative terminal first before removing the positive terminal and then replace the negative terminal last.

Don't rule out the new battery. Check the voltage at the battery posts and then the terminals with a load such as the lights, etc. turned on. Verify the voltage doesn't collapse when the starter key is turned to start position.

If the house batteries are lithium batteries, then a higher voltage is being applied to the starter solenoid than normal. That could point to a bad starter solenoid, but that is not likely.

[RonS]

I did check connections 1,2,3,4 and the connection to the starter. I have 12.6 volts. I did turn the ignition switch and checked voltage at battery 12.6 volts and didn’t change. But if the power isn’t getting threw the ignition it wouldn’t drop voltage. I did find a relay chassis disconnect lockout. I wonder if this could be the problem. I’m going to take the battery and have it load tested or install a different battery to test it,
Thanks for everyones help.

[Morich]

Quote:
relay chassis disconnect lockout

This is not one I know about. Relay chassis disconnect is one that when we turn the chassis battery disconnect, it is the relay that opens the power from the chassis battery to the chassis things like the starter?
Not sure what the lockout indicates , so really no firm ideas.
But a "lockout" might make me wonder if there is some other part of the scheme to make this relay "lock" and not operate???? I can't think of any reason and never seen one but if you have one, what does it do?
If this is a relay that you can see where power goes into a set of contacts, there should also be a wire where it comes out and I might want to verify it does come out?

No idea of what you are looking at but the idea of relays is pretty standard.
We expect to see two control wires go into some form of coil in the relay (power in and power out?)and when the control wires get battery power, it should move contacts open or closed. Those contacts should then have wires that actually pass the heavier current to the starter or what they operate.

Did not find a good drawing of a realy but this may do for what I'm wondering if you can get to the wires/contacts to check?
Not at all sure where this thought goes but if there is a chassis disconnect relay, we will want it closing and if there is a "lockout" what does that mean??

A thought to consider or ignore !!

[eyecando]

Lockout could indicate it is a latching relay where voltage applied to a relay coil latches a relay contact in one position and voltage applied to another relay coil in the same unit resets the relay.

Or maybe its a simple switch that is turned off with a knob.

As Richard indicated, there should be two large diameter wires that connect to the device. If it is 'locked out', there should be voltage only on one of the two wire terminals. If it is not locked out (normal position), there should be voltage on both of the wire terminals.

[Morich]

I think we may be wandering too far off the real problem when we get into the lockout??

Just going back to basics as I understand what is happening, I think it will be something missed that is much less "techie"!

I tried to do some crude drawings of the main parts of the action, leaving out lots of tech stuff that we might not be able to see or do much with anyway. Leaving out modules like PCM, TCM, and all those things as they seem to be working.
I can't draw them anyway!!

But if all is working normally, this is the power flow from chassis battery to starter solenoid and on to starter motor. The key contacts close and the starter solenoid closes the big contacts to make the path for power to go through the motor and turn it.



This is what most cars and trucks do with lots of clutter not shown. But there is something open on the OP's normal starting circuit. The red marks are the open at some point from battery to starter.
But then on RV we add the boost feature using the coach batteries to boost the chassis battery. If I understand correctly this works and the engine starts, so much of the tech stuff is out of the question?


The green path is where we expect power to get to the starter but it isn't doing it, so we have to say the path is open.
But if it is true that the starter works when the boost switch and the key contacts are closed, I think this purple path combined with the green path has to be what is happening!
WE get a full circuit but not to the chassis battery but use the coach battery.

I would not be looking for the high tech stuff like lockout, etc. but something very simple along the path from the chassis battery to the point where the coach battery cable meets the chassis battery cable. From the point where the coach battery meets the chassis battery seems to be good as it starts!

Winnebago does try to help us ID the cables with tape at the cable ends to match this code.



Since the problem seems to have come up when the battery was changed, I might go to that battery and make sure one cable did not drop down out of sight and get left off right at that point??

When you mention you are getting 12 volts at the starter, under what situation and are you sure it is chassis battery, not coach battery, as it seems not likely that path is good from chassis to starter.

But this is all theory and what you see is what we have to believe!!

[deckape]

I would remove the new batteries and take them to be tested . Then reinstall and check all connections for corrosion and tightest . It's aways the ground .

[Morich]

Originally Posted by deckape

I would remove the new batteries and take them to be tested . Then reinstall and check all connections for corrosion and tightest . It's aways the ground .

Chassis battery strap left off would be a simple on to happen!
Us human types do those things sometimes ---just to mess with our minds!

[RonS]

I think that I found the problem. The chassis disconnect switch located on the wall next to the entry steps . I noticed that I couldn’t turn it off the light would stay on. This didn’t happen before. Removed switch and checked continuity and found nothing. The power isn’t going threw the switch. I ordered a new switch and am waiting for it. I will let you know if it fixes the problem. Thanks for the help.

[Morich]

Okay, this is kind of common in trying to describe an issue and find a fix. We failed to communicate as well as needed!
Back in post 5 where I numbered spots to check the voltage, point 3 is the cable going to the disconnect relay and 4 is the power coming back. If you find good voltage at 3 but not at 4, that means the relay is open or not passing the voltage and needs to be checked.
It will have a set of small wires which send power through a coil to either open or close the contacts where the bigger wires attach. Using a meter, we can test that coil is good by checking it has continuity ( a good path?) from one small wire to the other.
Or we can push or flip the switch and listen for the relay to click and assume it is moving.
If it is moving we then need to verify that the contacts inside are actully good enough to make contact from the one big cable to the other. We can do this with a meter to test continuity passing from one big to the other as we open and close the relay. Or we can do the same by putting 12V on one big and seeing it gets through to the other side!
One way we use the meter as a resistance test and the other we set it to measure voltage.
But the bottom line question is if the power from the chassis battery gets through to go to the starter and that is where the problem started, right?

Some where along the line we did not talk the same or get the correct ideas passed. Glad we were not talking nuclear war!! No harm done!

[Bobn1957]

I maintained emergency power systems for 40 years and the standard was that if the battery voltage dropped below 9.5 volts when you engage the starter the battery needs to be replaced! I would put a meter on the battery and get the DW to try starting the RV, a new battery shouldn't go below 10 volts!

[jerichorick]

Originally Posted by RonS

Hello,
I replaced my chassis battery now MH won't start without using boost switch. No instrument lights & no engine crank.
Checked voltage at battery, all fuses in battery compartment, followed hot wire from battery to starter and have power, fuses under dash/engine compartment/external electrical panel/coverter fuses & replaced chassis relay switch behind exterior electric fuse panel.
Any other ideas?

Oh boy. Does this sound familiar. In my case I was cleaning the terminals. When I put it all back together it wouldn't start. I took everything apart and removed the batteries. When looking deep into the compartment with a flashlight I found a ground wire that had not been reconnected! Take another look at your work.



Hope that's all it is.


Rick

[Eagle5]

Husky won't start. Do you think it's the battery or alternator??
Cranking
Eagle5