Chassis disconnect switch

[Mike Jones]

I have 2 power disconnects on my 01 Marquis. One is for chassis and one for coach. When I turn off the chassis disconnect, it shuts off power to the whole coach. The coach disconnect does not shut off anything. I looked at the wiring in the switches and it looks correct according to a schematic that I found for it. And I believe is is only using my starter batteries for house power. If I disconnect my house batteries nothing changes. Any ideas.

Thanks in advance

Mike

[Mike Shumack]

It all most sounds like someone by-passed the House disconnect and routed the cables for the House side to the Chassis disconnect switch. Possibly the one disconnect switch failed and owner didn't want to replace it - however you said the cabling looks correct at both disconnects - could this rerouting have been done at the battery end?

Does the cabling-disconnect wiring setup look like this?

[Fred Brooks]

    Mike J,
 You may want to check the inverter fuse (250 amp shown in the diagram Mike S provided). It is not unusual for this to fail in the process of changing house batteries and accidentally touch the positive cable to ground. The fuse is hard to see and someone may have relocated the load side cable over to a chassis lug? somewhere. Check and see if your inverter is also connected to the chassis disconnect. If so, this will prove someone has moved the cables. Hope this helps, Fred

[Mike Jones]

Mike S, that is the same diagram I have and that is how it is wired. It seams that the whole coach is wired to one switch.

[Mike Jones]

Fred. I do know that the owner before me replace the inverter/charger. Maybe wired wrong?

[Fred Brooks]

     MJ, Difficult to get a positive and negative battery cable transposed at the inverter. The diagram the you have and Mike S provided shows a 250 amp "coach" fuse. This is also the "inverter/converter" fuse to protect the unit in the event there is a short or failure. If this fuse is blown, you would have no 12 volt to the coach or the inverter/charger. I would perform an ohm or continuity check across that fuse to verify it is operational.
    If you had the ignition key on or the engine running that would tie everything together. What is the voltage in the house batteries? If the house batteries are tied to the chassis batteries the voltage will be equal. Check one last time and see if there is a cable going from the chassis batteries "positive" over to the house battery "positive". Hope this helps, Fred

[Mike Jones]

Fred, the fuse is good, I checked the voltage on both circuits with engine off and they are different. The main issue I am having is it seems that all the power is running thru the chassis circuit. When I shut the coach circuit off everything still has power. When I shut off the chassis circuit it shuts off everything. I checked to see if the battery power cables were connected to the same terminal and they are not. Seems like both circuits are connected together somewhere. So when I dry camp it is using my start batteries for power and not my house batteries. Guess I will need to see where the circuits connect to coach just not sure where that is.

Thanks

[Steve Huber]

Mike,
There are 2 cables that you can trace to determine the apparent mis-wire. As mentioned earlier trace the + cable on the inverter to its source. The other cable is the one that comes to the front electrical bay and feeds the coach buss bar, located to the left of the chassis battery buss bar and solenoid. Using a tone tracer will make the task easier if you have one. You could also trace the cable feeding the DC breaker box.
Steve

[Mike Jones]

Thanks Steve, I will check that also.

Thanks

[Frank Bergamo]

Mike J,
on my 2002 Marquis, I had a battery isolator that was mounted just above the batteries in the left rear battery compartment. Did not have a solenoid that tied the batteries together that is in your schematic. Possibly one or both of the diodes failed in the isolator. Possibly miswired at isolator. There are 3 terminals on the isolator, middle one is from the altanator, the outside two go to each set of batteries. If you have a Echo Charger, it will be wired into the isolator as well. This might be a good place to start troubleshooting. Hope this helps,
                                                                                     Frank.

[Mike Jones]

Frank. I checked the isolator and it seems to be working correctly.

Thanks for your input

Mike

[Fred Brooks]

    Mike,
  Another common mistake that is made on older coaches is the LP detector. The original came with 2 red 16 gauge wires and the black ground wire. One of the red wires was connected to the chassis batteries, the other red wire was connected to the house batteries. When the detector is replaced, the new one only has 1 red wire. Sometimes the person doing the repair twists the 2 red wires together and connects them to the one red wire. This repair has now tied the chassis and house batteries together. Might be worth a look. Hope this helps, Fred

[Frank Bergamo]

Mike J,
the only other place that the battery banks could be tied together other than the battery isolator that I know of, is the battery boost solenoid. I believe it is mounted in the top, center of the battery compartment. Possibly failed in the closed position. Hope this helps.
                    Frank.

[Mike Jones]

Fred I will take a look at that.

Frank, I checked the voltage at the boost solenoid and the voltage on one side matched the start batteries and the other post matched the house batteries voltage, so I believe it is ok..

I haven’t had a chance to check the inverter circuit yet. But I do know the previous owner replaced it before I bought it so I am not sure which circuit he connected to.

I checked the power circuits in the Electrical compartment and when I shut off the house disconnect switch everything still had power. So not sure what it is connected to.

I am beginning to think he hooked both leads to the elec compartment together somewhere.


Thanks for everyone help

[Fred Brooks]

    Mike,
That being said, look at the ignition solenoid in the front run compartment below the drivers seat. That solenoid is a very common failure and one that eventually you deal with. Not uncommon for it to fail while in transit or on an adventure. The fast fix is to remove one cable on one side of the solenoid and then piggy-back it on top of the other cable to get you going until you can replace it. Another situation is the solenoid fails and gets replaced with a solenoid that is NOT continuous duty rating and they can fail in the "on" position. Most of us carry a spare Cole Hersey solenoid and a spare Delco Remy ignition switch. because of the failure rate. Hope this helps, Fred