Master switch no power

thomasinnv · April 23, 2019, 10:35:03 AM

Yes the dl3 does use a combined 12v/24v disconnect switch. Theres no telling what modifications/addons the po may have done. Proper configuration would be a dedicated lead from the 12v center tap at the batteries to the 12v junction block in the battery compartment which feeds all the ecm/tcm fuses ONLY. The large 12v center tap cable should feed a 105 amp circuit breaker next to the batteries, then the hot side of the main disconnect where the 12v lead from the vanner should also be connected. The switched side of the main disconnect should feed all other 12v loads. This configuration ensures that all 12v loads are disconnected with the exception of the ecm/tcm.

daddysgirl · April 23, 2019, 11:08:46 AM

This lists a lot of things that may not be relevant here, but it's a good source for troubleshooting some of those circuits.
http://www.mcicoach.com/service-support/serinfo/serinfo07K.htm

buswarrior · April 23, 2019, 12:27:06 PM

Did I see an new R&M fibreglass bus dashboard for sale on Facebook someplace?

Never can find stuff twice on there... wish peeps would be more active on the classifieds on BCM/BNO, where stuff doesn't disappear...

Happy coaching!
Buswarrior

Jcparmley · April 23, 2019, 02:20:43 PM

Ok, so I have 24 volts at the 30 amp breaker under the drivers window but nothing at the switch. So I opened up the dash and there was a bunch of additional devices wired into the dash. I believe they gps tracking units for fleet management. One box is a Verizon box labeled network fleet. The other is a cell and antenna. Either way I am not sure where to look for power on this switch and my manual dosen't have a wiring diagram for the master switch. Is there a way I can bypass the switch?

buswarrior · April 23, 2019, 02:30:55 PM

There's no bypass for the master switch.

Get the right pages with the schematics. If your book is missing stuff, get a new one.

Take careful pictures of all the wiring, you might make things worse as this continues...

Remove those other devices, they may have triggered a "power off" security feature. They will also be good candidates for parasitic power draining.

All wires that are extra add-ons, remove and terminate properly. Every one of them represents an electrical short later on.

Restored to stock, things will be much more pleasant.

Happy coaching!
Buswarrior

Jcparmley · April 23, 2019, 04:56:24 PM

That's great advice. The manuals I have are downloaded from the MCI website. I will nee to study them very carefully. I think your right about a "power off" feature because I can't find any power in the dash but I do have power in the front panel. Is there a way to reset the system? I put a high amp switch to the master ground in the battery compartment. I think that cuts off all power even from the parasitic draw. It also dosn't help that I am color blind. Good thing the wires have codes on them.

Quote from: buswarrior on April 23, 2019, 02:30:55 PM
There's no bypass for the master switch.

Get the right pages with the schematics. If your book is missing stuff, get a new one.

Take careful pictures of all the wiring, you might make things worse as this continues...

Remove those other devices, they may have triggered a "power off" security feature. They will also be good candidates for parasitic power draining.

All wires that are extra add-ons, remove and terminate properly. Every one of them represents an electrical short later on.

Restored to stock, things will be much more pleasant.

Happy coaching!
Buswarrior

Jcparmley · April 23, 2019, 05:21:24 PM

I cleaned up the master ground in the battery bay and also put a large cut off switch so I can cut the ground and stop any parasitic draws.

Quote from: richard5933 on April 22, 2019, 06:59:47 PM
Did you have a ground go bad? Or, is one of your master switches bad?

Jcparmley · April 23, 2019, 05:30:39 PM

Could you post a pic or send me a pic of how your batteries are connected? Also, If one of the fuses on either the ECM or the TCM would blow would that shut the whole system down? Perhaps there was a short when the batteries were switched out?

Quote from: thomasinnv on April 23, 2019, 10:35:03 AM
Yes the dl3 does use a combined 12v/24v disconnect switch. Theres no telling what modifications/addons the po may have done. Proper configuration would be a dedicated lead from the 12v center tap at the batteries to the 12v junction block in the battery compartment which feeds all the ecm/tcm fuses ONLY. The large 12v center tap cable should feed a 105 amp circuit breaker next to the batteries, then the hot side of the main disconnect where the 12v lead from the vanner should also be connected. The switched side of the main disconnect should feed all other 12v loads. This configuration ensures that all 12v loads are disconnected with the exception of the ecm/tcm.

Jcparmley · April 23, 2019, 06:45:42 PM

So as I was looking behind the dash at these gps devices the PO installed. The installation was very messy. It looks like some of the wires connected to the master switch was exposed and it shorted out somehow. There are some evidence of a short by some burn marks on the wire insulation. So I followed the wires to the harness and unplugged the harness. I then attempted to test the pins in the harness for voltage and didn't get a reading at all. So I have been looking at the schematics and can't seem to find a diagram that shows the master switch and what wires go on what pins.

DoubleEagle · April 23, 2019, 07:24:51 PM

Quote from: buswarrior on April 23, 2019, 12:27:06 PM

Did I see an new R&M fibreglass bus dashboard for sale on Facebook someplace?

Happy coaching!
Buswarrior

I saw it too, briefly, he wanted $300 for it. I have one myself, that I never used.

thomasinnv · April 23, 2019, 07:37:35 PM

The 30 amp breakers provide power to several components and accessories, a 3 amp breaker provides power to the main switch, which in turn energizes the main relay turning everything on. Do you have a decal inside the front jbox door? The 2 breakers in question are shown as "V" and "CC" on mine, likely the same on yours.

Jcparmley · April 23, 2019, 08:34:15 PM

I don't have a decal on the door. I looked at the manual schematic and checked The breaker labeld cc and I do have power. I did not check the one labeld V. I will check that tommorow. If "v" dosen't have power where would I go from there? Is there some sort of breaker behind the dash that could have shorted out to protect other circuits?

Quote from: thomasinnv on April 23, 2019, 07:37:35 PM
The 30 amp breakers provide power to several components and accessories, a 3 amp breaker provides power to the main switch, which in turn energizes the main relay turning everything on. Do you have a decal inside the front jbox door? The 2 breakers in question are shown as "V" and "CC" on mine, likely the same on yours.

thomasinnv · April 23, 2019, 09:14:06 PM

Breaker V supplies power to the switch, the switch then powers the main relay. If you have no power on breaker V but there is power on the main bus bar then the breaker is faulty.

Jcparmley · April 24, 2019, 06:48:13 AM

Ok, I will test that this morning. Thanks

Quote from: thomasinnv on April 23, 2019, 09:14:06 PM
Breaker V supplies power to the switch, the switch then powers the main relay. If you have no power on breaker V but there is power on the main bus bar then the breaker is faulty.

daddysgirl · April 24, 2019, 06:49:14 AM

Does your book have a schematic for "Starting and Charging" or "Motor Controls"? If so, the wires for the switch, and the circuit for the relay should be shown on one, if not both of them.