Master switch no power

Jcparmley · April 22, 2019, 04:42:44 PM

A couple weeks ago I brought my MCI 102dl3 into the shop just to get a inspection before I purchased it. Everything checked out ok. However, the next day when I went to pick it up the batteries were only at 20 volts and wouldn't start. So I borrowed the batteries from the C3 bus I have and installed them into the DL3 bus. It started up and I drove home. Then I parked it and turned off the main shutoff.

A couple days passed and I went to start the bus and no power to the master dash switch. So I checked the batteries and they were drained again. I disconnected the batteries and charged them over night and hooked them back up with the same result. So I must have something that is draining my battery. I will need to chase that down. However, my main problem now is that I get 24 volts at the main switch in the battery compartment but nothing at the dash.

Is there a fuse Somewhere that I'm missing? I checked with my voltmeter for power in the front junction panel by the drivers side and I have no power anywhere even though I have power at the battery, vanner, etc. So somewhere between the battery compartment and the dash (and engine bay panel) I am loosing the connection. I have done a bunch of searches on the forum and read a lot of posts but just can't seem to find the solution.

THanks for the help

windtrader · April 22, 2019, 05:40:40 PM

There is a master disconnect switch to cut off the start battery from the coach. On my MC8, it is in the battery bay.

Jcparmley · April 22, 2019, 06:58:17 PM

Yes, what's weird is when the main disconnect in the battery bay is on my master switch in the dash has no power. So I am wondering if there is a fuse or something I am missing between the batter bay and the master switch on the dash?

Quote from: windtrader on April 22, 2019, 05:40:40 PM
There is a master disconnect switch to cut off the start battery from the coach. On my MC8, it is in the battery bay.

richard5933 · April 22, 2019, 06:59:47 PM

Did you have a ground go bad? Or, is one of your master switches bad?

Jim Blackwood · April 22, 2019, 09:05:45 PM

You checked the output lugs from the master switch?

Jim

bevans6 · April 23, 2019, 04:03:00 AM

The circuit for a 1989 MC-9 is battery to master disconnect to AC panel (roof of front luggage bay) bus bar with no breaker in the path. From AC bus bar via 105 amp auto reset breaker to front panel bus bar. From front panel bus bar via 30 amp breaker to master switch. I think that is also an auto reset breaker, in the main panel. On my bus 1980 MC-5C, the 30 amp breaker is the lower left most breaker, and the only 30 amp breaker, screwed into the bus bar. I would look for voltage on the main panel bus bar and the output of the 30 amp breaker before I took the dash apart. The main output connection point from the master switch is stud 14 in the main panel.

Brian

daddysgirl · April 23, 2019, 05:03:20 AM

My circuit is basically the same as what Brian mentions, with the 30 amp master switch feed breaker in the front panel. As for the batteries draining down, do you have a single 12v wire coming off the battery? If so, look and see what is on the stud that is fed by the 12 volt spare. It can run down the battery quickly without a battery minder.

bevans6 · April 23, 2019, 08:48:17 AM

An equalizer can drain batteries also, some are wired directly bypassing the disconnect switch so they are always on.

thomasinnv · April 23, 2019, 09:10:10 AM

On the dl3 the main disconnect does NOT disable the vanner, as the ecm and tcm are supplied constant power. As for the no power at the dash, others have pretty much covered what needs to be checked. Follow the path, starting at the output side of the disconnect. Then on to the ac box, then the driver side box. Once you get the power restored, we can proceed with steps to troubleshoot the possible reasons for your battery drain.

Jcparmley · April 23, 2019, 09:15:11 AM

Yes, I checked the output lugs on the master switch inside the battery compartment. It is working correctly at over 24 volts.

Quote from: Jim Blackwood on April 22, 2019, 09:05:45 PM
You checked the output lugs from the master switch?

Jim

Jcparmley · April 23, 2019, 09:17:50 AM

Ok, I will check those out today. Is the 30 amp breaker a manual or auto reset. If it's auto then it should have reset itself. Thank you for your advise. I will post what I find this afternoon.

Quote from: bevans6 on April 23, 2019, 04:03:00 AM
The circuit for a 1989 MC-9 is battery to master disconnect to AC panel (roof of front luggage bay) bus bar with no breaker in the path. From AC bus bar via 105 amp auto reset breaker to front panel bus bar. From front panel bus bar via 30 amp breaker to master switch. I think that is also an auto reset breaker, in the main panel. On my bus 1980 MC-5C, the 30 amp breaker is the lower left most breaker, and the only 30 amp breaker, screwed into the bus bar. I would look for voltage on the main panel bus bar and the output of the 30 amp breaker before I took the dash apart. The main output connection point from the master switch is stud 14 in the main panel.

Brian

Jcparmley · April 23, 2019, 09:19:34 AM

That sounds good I appreciate the help.

Quote from: thomasinnv on April 23, 2019, 09:10:10 AM
On the dl3 the main disconnect does NOT disable the vanner, as the ecm and tcm are supplied constant power. As for the no power at the dash, others have pretty much covered what needs to be checked. Follow the path, starting at the output side of the disconnect. Then on to the ac box, then the driver side box. Once you get the power restored, we can proceed with steps to troubleshoot the possible reasons for your battery drain.

thomasinnv · April 23, 2019, 09:21:12 AM

Go into the front left luggage compartment, look up and open the ac junction box. There is most likely a sticker inside the cover, find and check the main 24v input from the battery compartment and output to the front jbox. If there is no schematic inside the cover then it's time to bust out "da book"

buswarrior · April 23, 2019, 09:29:00 AM

I've found that the equalizer by itself, won't drain the batteries, all things being normal, healthy batteries, etc.

However, a 12 volt load will trigger the equalizer to do its job...

The equalizer has a prescribed connect and disconnect order for the cables, some have got away with ignoring them?

If you control the 12 volt loads, then the equalizer should be ok left in the stock circuit location and you don't have to wonder about a self inflicted smoke escape?

On a unit I was involved with, there was a 12 volt shut-off added to the wall, right beside the 24 volt cut-off in the battery compartment.

Newer coaches, it is a combined switch for the 2 voltages.

Happy coaching!
Buswarrior

Jim Blackwood · April 23, 2019, 10:03:48 AM

I think the DL3 has the combined switch. It sounds like two issues to me, power to the front panel, and an unswitched draw. So for the second the 12v side of the vanner seems to be the place to start, perhaps by isolating (disconnecting) all loads coming off it. For the first that left bay panel sounds like the logical next step.

Jim