Continuing mystery with DC system (with pics)

[whopay]

When I connect the wire to the battery (marked with the red arrow in the photo) the RV will not accept power, and if I do it with power on, it will immediately cut the master switch, and even the engine starter will not work.

I think it is the wire that goes to the generator based on the schematic photo shown. What could be causing this?

 

[Grumpy]

What terminal are you connecting it to? It's a positive wire unless someone removed the white tape.

 

[whopay]

Yes- The positive.

 

[Learjet]

They make a lot of different C class RVs and we are not mind readers...how about year Make and Model?

 

[JimD]

First thing I would do is verify the battery cables are going to the correct terminals on the battery. There should only be 1 cable connected to the negative post and that cable should run to chassis ground. That should be easily verified by a visible inspection. While inspecting the connection to the metal frame verify it is a good solid clean and tight connection. Many times this connection will corrode or loosen and cause all kinds of headaches. Simple check while you are already down there.

The other cables should all connect to the positive post. If you have no idea where each cable goes just connect one at a time and see what works. The coach 12 volt system cable should allow the 12 volt lights to work. The generator cable should allow the generator to turn over. The levelling power cable should allow that system to function. The last cable will connect to the solenoid that allows the house battery to charge from the vehicle's charging system.

If connecting a single cable causes problems then you first need to know what circuit is being connected and go from there. I would find it hard to believe the cable being connected can cause it to bring down the system as other problems should be apparent. If the cable was rubbed bare and touching ground you would get major sparks when connecting it to the battery. The circuits that you are connecting are basically dormant until you activate them so just connecting a power cable should not cause problems.

Looks like further research is warranted.

 

[whopay]

Excellent feedback!
So this is a 2018 Jayco Redhawk 26XD
I have ground already attached, I will chase it to make sure it’s good but…
With the yellow marked positive wire connected literally everything works BUT the generator. As soon as I connect this wire marked by the red arrow to the positive, EVERYTHING quits. Right now I’m just leaving it disconnected but I’d like to try and figure out the likely short/etc to get the generator going again.
I have chased the cable as much as possible and don’t see any rodent damage so I’m assuming I have a bad/shorted relay somewhere?

PS: no leveling kit

 

[Kevin Cooper]

If you have an ohm meter, check from the negative post to that cable with the issue. What happens? Should be OL. If continuity, then something it shorted or wired incorrectly, or a part has failed.

 

[whopay]

Yes. The neg checks out with continuity.

So where would y’all look on this wire? I have the schematic shown but I have no idea where that 80A mini breaker is. I’m also fairly certain there are components not listed in this schematic, like the starter solenoid for the generator.

 

[Grumpy]

I’m also fairly certain there are components not listed in this schematic, like the starter solenoid for the generator.

That is internal to the geny so it won't show on the schematic.

 

[Kevin Cooper]

Look at figures #18 and #20 on pages 29 and 30.
https://www.cummins.com/sites/default/files/rv-manuals/0981-0621.pdf
I would pull the conductor off the breaker and retest for continuity. It should be OL. If not, bad breaker, If cleared, then, I’m thinking you will see the problem on the next conductor going to the starter, or the starter is fried.
Best Wishes!

 

[craigav]

When I connect the wire to the battery (marked with the red arrow in the photo) the RV will not accept power, and if I do it with power on, it will immediately cut the master switch, and even the engine starter will not work.

I think it is the wire that goes to the generator based on the schematic photo shown. What could be causing this?

It is hard for me to tell in the image but something to note is that the black/yellow wire is listed to be a 6awg and the wire to the generator is listed to be a 2awg (both sides of an inline breaker generally have the same gauge wire).

Therefore, the wire going to the generator should be visibly larger than the wire next to it being it is a 2awg wire and the black\yellow is a 6awg (perhaps ~150% larger) and I can't tell in the image if that is the case, something to check though.

Taping a wire with white tape is common to denote it is a ground however, sometimes tape can come off so it is possible that it had a white tape at one time (I will add that the tape generally stays in place though).

If you can grab a few pictures of the battery and its connections along with the area nearby where the disconnect solenoid is located and likely the breaker you mentioned, that could be very helpful. ~CA

 

[craigav]

One other question that could be helpful to know is what led up to this issue? (not to sound negative). The reason I ask is that it would be helpful to know if the problem simply occurred one day while everything was connected and working fine and then the problem occurred and you removed the wires to test for the source of the issue or if you had removed\replaced the battery (or some other components) just prior to the issue occurring. It does appear by the shiny copper on the terminal ends that both terminal connections in the image were recently connected, could it be that there is another possible connection within the black (no tape) wire's reach? ~CA

 

[Lauren8363]

I hope by now that you have found and corrected your issue, but a simple rule of thumb is: Check every connection that you can put a wrench on. A “High Ground” (loose connection) will cause more problems than you can shake a stick at, and some that won’t make any sense. The DC system is so dependent on solid connections, both positive and negative, but in most cases it is in the grounding circuit. It may be fine for a while, but eventually a loose connection will get a small amount of carbon (or dirt) between the points of connection and will over time will only get worse and worse, eventually stopping all flow of electricity.

Worse yet, as that connection gets worse, it can start to “Arc” which will increase the carbon buildup and then it will just “Snowball” uniting ie actually starts to burn.

For this reason RV owners should regularly inspect and tighten connections as needed. If you find one that is loose I recommend disconnecting the power then take the connection apart, clean all surfaces with a very fine sand paper Then clean all with 90% rubbing alcohol and re-assemble.

 

[Leon-JAY]

Mystery DC system

Put a voltmeter on it to confirm voltage and polarity.After try to connect ground

 

[whopay]

One other question that could be helpful to know is what led up to this issue? (not to sound negative). The reason I ask is that it would be helpful to know if the problem simply occurred one day while everything was connected and working fine and then the problem occurred and you removed the wires to test for the source of the issue or if you had removed\replaced the battery (or some other components) just prior to the issue occurring. It does appear by the shiny copper on the terminal ends that both terminal connections in the image were recently connected, could it be that there is another possible connection within the black (no tape) wire's reach? ~CA

Still working on this.

This is a fair question. The jist of the start of this was the master switch for interior power was apparently left on for several days. When my wife tried to turn it off it would switch itself back to on.
When I got back in to town the switch was then off and the battery stone dead and would not accept a charge while connected. I removed the battery and was able to charge it. But when I fully connect it will work, but not once I connect the generator to the positive battery post. Then nothing works.

 

[whopay]

One issue I am having is I don’t know where these breakers and fuses are. There are a ton of them everywhere. I see a solenoid behind the battery, and one beside the generator.

I’m still not convinced enough where to start. Those two solenoids perhaps. Maybe the master power switch. Maybe the generator is grounded out at the starter or somewhere else.

I got schematics from Jayco, but there really more like builder diagrams of where to install wires, not actual schematics to chase wires.

I have checked all connections, nothing that is visible.

 

[whopay]

Look at figures #18 and #20 on pages 29 and 30.
https://www.cummins.com/sites/default/files/rv-manuals/0981-0621.pdf
I would pull the conductor off the breaker and retest for continuity. It should be OL. If not, bad breaker, If cleared, then, I’m thinking you will see the problem on the next conductor going to the starter, or the starter is fried.
Best Wishes!

Is this breaker in the generator bay?

 

[whopay]

Fixed. Turns out it was incorrectly attached battery leads. My configuration is like most: one lead on the negative terminal, three on the positive. While that set up seemed obvious when I disconnected, two of the terminal leads looked so similar it was impossible to tell which went where since I didn't mark them. It took some time with a volt meter and some trial and error to get it.

 

[norty1]

Thanks, You never know how many people never return once a problem is fixed to close the story. Wish more would help their fellow campers by doing what you just did!

 

[Kevin Cooper]

Very happy you figured it out! You did a lot of learning to get there!