Master switch no power

[daddysgirl]

While testing my positive lead on the voltmeter touched two pins on the back of the main power switch and everything lit up and the traditional beeping low air began.

Is it possible to do this safely and start the bus to move it?

I am still trying to find what wires go to what pins on the back of the main dash switch.  I have some wires that were pulled out and I am trying to figure out what pin they go to. 


Do these wires have MCI codes on them? If so, what circuit codes are they? If they are coded circuits, you can use those codes to replace the wires while the battery is charging.

As far as the parasitic draw I haven't figured that out yet.  I am trying to get the beast started so I can move the bus to a better place to work on it.  Then I will try to figure out what is drawing the battery down.

When you get to that point, I have a really detailed diagnostic chart for the equalizer.

[buswarrior]

Oooh! A diagnostic chart for an Equalizer?

Please do post that up here as an attchment!

Happy coaching!
Buswarrior

[daddysgirl]

Oooh! A diagnostic chart for an Equalizer?

Please do post that up here as an attchment!

Happy coaching!
Buswarrior

Certainly. 
There is a functional test and advanced diagnostic test
http://www.mcicoach.com/service-support/serinfo/mm0707.pdf

[thomasinnv]

Rather than reinvent the wheel, go back to oem setup. One of my previous posts explains the proper configuration the way MCI intended it to be. ECM and TCM fuses all off the center tap, everything else (both 12 and 24 volts) runs through the main disconnect. The bus should be able to set for months without issue with only the ecm and tcm powered. If not, you have a wiring problem or a short in one of the modules.

Charge the batteries up and start fresh.

[Jcparmley]

I unhooked the batteries and will let them sit overnight and see if they will keep a charge overnight.  I also took out the master dash switch out of my c3 bus and installed it into the DL3.  I then used a jumper to bypass they "V" breaker and the switched worked.

So that tells me that my original master switch is bad.

I also know for sure that the "v" breaker is bad, so that needs replaced. 

I also compared the engine start switch on the c3 to the DL3 and noticed that the c3 starter switch has many wires connected to it but the DL3 does not.  The strange thing is I don't see any loose wires that are not connected behind the switch so it must be wired differently.   I will try to look through the manuals I downloaded and get a pin layout.

Furthermore, I was able to get the starter activated by bridging two of the pins on the back of the master dash switch but the engine didn't start.  It just cranked but did not start.  So my guess is even though I can activate the starter the fuel pump must not be activated and therefore the engine will just crank but not start.

So tonight I am going to look for the installation diagrams of the "gps" devices that were installed and see if I can put this all back together the way MCI designed it.  I am still trying to figure out what wire goes on what pin on the back of the switches.  There has to be a diagram somewhere that I am missing.

[Jcparmley]

Also, when referring to the "center tap" what does that actually mean?  Is it the cables coming off the positive side of the batteries, or is it the feed side of the battery disconnect switch?  I know it's a dumb question but I just want to be sure I am understanding everything. 

[richard5933]

Also, when referring to the "center tap" what does that actually mean?  Is it the cables coming off the positive side of the batteries, or is it the feed side of the battery disconnect switch?  I know it's a dumb question but I just want to be sure I am understanding everything.

Usually refers to connecting between the two batteries in a 24v system to access 12v. Here's a manual from Vanner (may not be yours, but the diagrams are pretty much the same for most of these) - lots of wiring diagrams and a good explanation. Hopefully it will be helpful.

[MagnoliaBus]

Also, when referring to the "center tap" what does that actually mean?  Is it the cables coming off the positive side of the batteries, or is it the feed side of the battery disconnect switch?  I know it's a dumb question but I just want to be sure I am understanding everything.

Center tap is connecting to the jumper between two 12V batteries that are wired in series in order to make 24V.

[daddysgirl]

FWIW...I have attached a picture (it's my old setup) that shows a 12V wire.
I have a different configuration, but the 12 volt wire is the black wire going up the right side of the compartment. It is connected to the right battery on the post second from right.

[richard5933]

FWIW...I have attached a picture (it's my old setup) that shows a 12V wire.
I have a different configuration, but the 12 volt wire is the black wire going up the right side of the compartment. It is connected to the right battery on the post second from right.

See page 5 of the manual I posted for the simplest wiring diagram for the Vanner.

FWIW, that 12v wire seems undersized for the task at hand. How many amps are you pulling 12v total?

[daddysgirl]

That wire was OEM, 10 gauge that only fed front stud 55 (12 volt spare) Dad had a couple gadgets powered by that stud, but my system is a bit different now. When I'm finished, I won't need that wire.

That said... if I didn't plug the battery minder in, the left battery died fast and quiet.

[richard5933]

That wire was OEM, 10 gauge that only fed front stud 55 (12 volt spare) Dad had a couple gadgets powered by that stud, but my system is a bit different now. When I'm finished, I won't need that wire.

That said... if I didn't plug the battery minder in, the left battery died fast and quiet.

Something is definitely wrong with the way the Vanner equalizer is connected then - if it's done correctly both batteries should be used equally. Having one drop like that is an indicator that either the wiring is done wrong or the Vanner has failed.

[thomasinnv]

My manual shows only 2 wires connected to the master switch. One wire comes from the 3 amp breaker, the other feeds power to the solenoid which activates the main relay.

It is likely the reason you could crank but not start is becuase the ecm probably isn't getting power. Check all the ecm fuses they are in the little compartment to the right of the batteries. If all is good there, turn on the main switch and make sure you are getting power through all contacts on the main relay. In all of your messing around with the batteries and wiring it is possible you blew a ecm fuse, it doesn't take much to blow one.

[Jcparmley]

Thanks Richard.  I will check that out.

Usually refers to connecting between the two batteries in a 24v system to access 12v. Here's a manual from Vanner (may not be yours, but the diagrams are pretty much the same for most of these) - lots of wiring diagrams and a good explanation. Hopefully it will be helpful.

[Jcparmley]

Ok, thanks Derrick I will check the fuse tomorrow.  Do you happen to have a diagram for the engine start switch?

My manual shows only 2 wires connected to the master switch. One wire comes from the 3 amp breaker, the other feeds power to the solenoid which activates the main relay.

It is likely the reason you could crank but not start is becuase the ecm probably isn't getting power. Check all the ecm fuses they are in the little compartment to the right of the batteries. If all is good there, turn on the main switch and make sure you are getting power through all contacts on the main relay. In all of your messing around with the batteries and wiring it is possible you blew a ecm fuse, it doesn't take much to blow one.