Intermittent loss of DC coach electricity

[tallguy]

I have an occasional and intermittent problem with loss of DC coach power. Here's the scenario: I drive into a rest area for a "comfort" stop, turn the engine off, switch the water pump on, it doesn't come on, further investigation reveals no DC power in the coach. I don't lose DC power every time the engine is turned off, but when I do starting the engine or plugging into shore power restores DC power. What might cause this, and what is the fix?

Coach is a 2004 Fleetwood Pace Arrow, on a Workhorse chassis.

[nothermark]

salesman's/storage switch or relay.

I'd start by toggling the switch. It might have accidentally been pushed.

[tallguy]

Originally Posted by nothermark

salesman's/storage switch or relay.

I'd start by toggling the switch. It might have accidentally been pushed.

Those switches are inside a cabinet, behind a door, so it's unlikely. Also, why would power come back on without toggling them?

[twinboat]

Starting the engine activates the isolation relay, suppling chassis battery power to your 12 volt accessories.

Plugging in shore power actavates the converter doing the same thing.

If this is an occasional thing, I would check the cable connections on the house battery. Take them off and look for a slight, white coating of corrosion.

Because the 2 power sources are on either side of the salesman switch ( battery disconnect ), I don't think it's the problem. If it was not connecting, the isolation relay wouldn't restore power. It runs directly to the battery. The converter connects to the system on the RV side of the salesman switch.

[nothermark]

Originally Posted by tallguy

Those switches are inside a cabinet, behind a door, so it's unlikely. Also, why would power come back on without toggling them?

If you don't know you are turning them off you also probably don't know you are turning them on. As yours are behind a cabinet door that probably is not your problem. It is a common problem in many/most units.

From your description I would still think about pulling out a meter the next time I lost power and checking where it disappears. Twinboat may have hit it with the battery. It may also still be the relay or a loose cable.

[Bigd9]

Like Twinboat mentioned, my first place to look would be the battery connections.

[nothermark]

Agreed. The second place would be the relay. Easy to hit both on most MH's.

If you go back through posts TB and I generally agree on troubleshooting. One of us will sometimes build on the other. That's not disagree, it is "if that does not work go here". I think we have the same roots in how to troubleshoot systems. Comes from WWII era instructors that taught us to learn the system and analyze failures instead of "read the decision tree" or "call tech support" as seems to be the case these days. The latter is an offshoot of computer controls. One cannot look at a schematic and analyze operation in many cases because everything goes to a magic box we are not given privy to the instruction set for.

[tallguy]

Originally Posted by twinboat

I would check the cable connections on the house battery.

It turns out one of the cables was ever so slightly loose. When I moved the batteries slightly to have better access to the posts the DC power went out!

On the road again on Thursday. Keeping my fingers crossed!

[twinboat]

Great, enjoy your trip.

[nothermark]

Glad you found it.

[JohnRR]

Thank you for the update they are important for those who may do a search of the subject in the future.