Master switch no power

[Jcparmley]

Ok, so I wired the battery compartment the way it was when I purchased it with the disconnects.  Once I did that I was able to activate the dash master switch and I was able to see the Trans console light up.  That's a good sign. 

Of course whatever was draining my battery when I purchased it will need to be found but for now I am just happy to have power to the computers.  Anyhow, my engine start switch is either bad or not wired up correctly.  So I looked at the engine start switch on my C3 bus and it has 4 wires connected.  Two white, a red and black and a brown wire.  I believe the brown wire is supposed to come off the 14 stud in front J box.  I looked all over behind the dash and I am unable to find the brown wire.  Perhaps the switch is supposed to be wired differently than the C3 start switch.

So I wend and plugged the ECM back into the harness and started the bus jumping the two main terminals of the starter solenoid.  Low and behold the bus strarted right up.  Yah! The ECM isn't fried.

Now I just need to figure out how the start switch is wired and then trace where the battery draw is coming from.  Does anyone know which wires go to which pins on the start switch?  Thank you all so very much for your help.  I appreciate it very much.

[Jcparmley]

I'm not sure if it was connected when I brought it home.  I found it hanging there when I opened the panel.  Do you know where it goes?  It has a screw on the end so it must go to a terminal somewhere.  Thanks Andrea for your suggestion of going back the the wiring the PO had.  When I did that I was able to start the bus.  I really appreciate the help.  Do you happen to know how the start switch on the dash is wired?

Code 10 should be a low water level sensor. That might explain why the voltage is low on that pin...maybe it caused a prior issue. Was it connected when you brought it home?

[daddysgirl]

YES!!!!!!!
You're a electrical nut now.

EDIT: You're more than welcome...that's what we're here for. Someone had to walk me through the same process a few years ago. Without this board, i would have lost my mind. So glad it started.

[daddysgirl]

Let me look. Should be 2 or 3 wire codes, but I have a wonderful old school button. The wire codes should be the same.

The following is what I have. BEFORE YOU DO ANYTHING...TAKE PICTURES OF EVERY WIRE BEFORE YOU MOVE IT    Remember...you drove it home.
EDIT:
My schematic has 2 red code 29 wires on it. One of them goes from FRONT STUD #4 to the button; the other goes from the other side of the button to the MIDDLE pin on the master start switch, OVER black wire #3.
Wire id 3 goes from STUD #14 to the right side of the master switch, then to a 30 amp breaker in the FRONT junction box.

So, MASTER SWITCH: one wire id 3 on one side...2 wires id 3 and id 29 on the other.  But this stuff is getting familiar to you now.

Can you post your "Charging and Starting" diagram?

START BUTTON: 2 wires, both id 29. One getting power from stud 4, the other moving on to the master switch.

[daddysgirl]

Question about the code 10 wire: But save the question for when you work on that circuit...just grab the screw. Do  not loose those.

Was that hanging in the rear junction box, just behind the rear most axle on the driver side, or the remote junction box at the rear of the engine all the way in the back? I'm hoping you're gonna say big rear J box.

[Jim Blackwood]

JC, I'm attaching photos of the back and front of my main power and start switches. Hopefully that will help.

That beeper is indeed the Low Air Pressure beeper. Mine is very loud though, I may have to put some tape across it to tone it down a little. Very annoying (and yes I realize it is supposed to be).

If you have 12v on the pin for the CEL I'm guessing the ECM grounds it to turn on the light. Probably the same with the SEL I'd guess but where does that even go? Doesn't seem to match any of the pins you listed.

Did you not find a wire to match up with that 10p wire in the photos I sent earlier? I could probably pull the cover again and look for it if your remote box looks the same as mine.

Jim

[Jcparmley]

It's hanging in the remote start junction box all the way in the back.  It's the one where you can flip the toggle and start the engine from the back.

Do you want a pic of the way I have the batteries now or the way MCI says it should be run?  Thanks

Question about the code 10 wire: But save the question for when you work on that circuit...just grab the screw. Do  not loose those.

Was that hanging in the rear junction box, just behind the rear most axle on the driver side, or the remote junction box at the rear of the engine all the way in the back? I'm hoping you're gonna say big rear J box.

[Jcparmley]

Hi Jim

I will compare your pic of the rear remote box with what I have.  I believe comparing what I have with your pic should tell me where that 10p wire goes.

In regards to the pic of the start switch.  Where does the red/black wire connect?  And where does the brown wire connect to?  Those are the two that I am missing.  Strange because that switch worked a week ago.  I can't seem to find that brown wire anywhere.

JC, I'm attaching photos of the back and front of my main power and start switches. Hopefully that will help.

That beeper is indeed the Low Air Pressure beeper. Mine is very loud though, I may have to put some tape across it to tone it down a little. Very annoying (and yes I realize it is supposed to be).

If you have 12v on the pin for the CEL I'm guessing the ECM grounds it to turn on the light. Probably the same with the SEL I'd guess but where does that even go? Doesn't seem to match any of the pins you listed.

Did you not find a wire to match up with that 10p wire in the photos I sent earlier? I could probably pull the cover again and look for it if your remote box looks the same as mine.

Jim

[daddysgirl]

It's hanging in the remote start junction box all the way in the back.  It's the one where you can flip the toggle and start the engine from the back.

Do you want a pic of the way I have the batteries now or the way MCI says it should be run?  Thanks

The schematic of the entire circuit (MCI) should be more clear, but it will show you the switches also. If you have a pic of the battery bay now, if you post it you'll never loose it.
But did you take one of those switches off your other bus last week? If so, are they the same switch?

ALSO...if you look at the breakers in the remote J box, look to see if one of the terminals is cleaner than the rest...you might get lucky and be able to see where the screw came loose. There aren't that many screws in that box.

[Jcparmley]

I took the master dash switch off my other bus and that is working.  I havn't taken the engine start switch off the other bus yet.  My hope is when I find the correct wire it will work.  My only day off is on Monday so I hope I can get this all working correctly tommorow.  I will take pics of my battery bay tommorow and post it.  Perhaps you all can diagnose the problem right away.  The hint that perhaps the terminal where the 10p wire goes may look less corroded is a great hint.  This is still all new to me. 

Once this is figured out I will try to figure out why I have no fast idle or cruise control.  Perhaps it's all related.  Are you all still up for helping me get this right?  You have been a great help already.  I hope my problems and questions arn't burning you all out.

[Jim Blackwood]

Why, you don't have any abandonment issues do you?

Just for you, I went out and took a gander at those wires again. The red and the brown both run down to the big multi-pin connector. Didn't get the pin numbers or where they go from there 'cause it's dark, but they should be in that bundle somewhere.

Jim

[luvrbus]

lol running before I worked on it so I screwed something up happens to all of us

[daddysgirl]

lol running before I worked on it so I screwed something up happens to all of us

Oh yes, it surely does.

I was thinking...(dangerous I know) that it might be beneficial for future reference to start a new thread for finding and fixing the parasitic drain? Bus start one topic...hunting another? Just a thought

[Jcparmley]

The PO totally chopped up the switch wiring.  For one thing I can't find the brown 29p wire that is supposed to be on the starter switch.  I can see the wire on the 4 post in the front j box but can not find it behind the dash.  Also, the PO has a red wire attached to the black 3r wire that is supposed to be on the master dash switch.  I also have a green 4 wire that I thought was supposed to go to the master dash switch on the post above the black 3 wire, but Andrea said on her switch she has the red/black 29 wire going to that post.  So I am not sure how this is supposed to be wired.  Here is a pic

Let me look. Should be 2 or 3 wire codes, but I have a wonderful old school button. The wire codes should be the same.

The following is what I have. BEFORE YOU DO ANYTHING...TAKE PICTURES OF EVERY WIRE BEFORE YOU MOVE IT    Remember...you drove it home.
EDIT:
My schematic has 2 red code 29 wires on it. One of them goes from FRONT STUD #4 to the button; the other goes from the other side of the button to the MIDDLE pin on the master start switch, OVER black wire #3.
Wire id 3 goes from STUD #14 to the right side of the master switch, then to a 30 amp breaker in the FRONT junction box.

So, MASTER SWITCH: one wire id 3 on one side...2 wires id 3 and id 29 on the other.  But this stuff is getting familiar to you now.

Can you post your "Charging and Starting" diagram?

START BUTTON: 2 wires, both id 29. One getting power from stud 4, the other moving on to the master switch.

[Jcparmley]

Yes, good idea.  I will start a new thread when I begin looking for the drain. 

Oh yes, it surely does.

I was thinking...(dangerous I know) that it might be beneficial for future reference to start a new thread for finding and fixing the parasitic drain? Bus start one topic...hunting another? Just a thought