School Bus Fleet Magazine Forums
Home | Profile | Register | Active Topics | Members | Search | FAQ
 All Forums
 Professional Garage
 Enter Forum: Professional Garage
 2007 C-2 electrical/electronic problems
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

BJ Henderson
Advanced Member

USA
280 Posts

Posted - 04/03/2014 :  09:34:55 AM  Show Profile  Send BJ Henderson an AOL message  Reply with Quote
I have a 2007 C-2 with crazy symptoms. Like a loose ground in 4 ways or left turn, headlamps, either or both sides and the top lamp on the stop sign are on or off intemittently.

I had to repair corrosion damaged connectors on the CHM module (the one behind the left front wheel up in the fender) I thought the entire problem stemed from there. Repaired and after repair didn't fix replaced the CHM module later. Still not repaired, but at least I know that connection and module (module connector had corrosion rust damaged connectors) should be good now.

The info center on the speedo says no J1857 communications. The laptop shows 231 for active code, no J1939 communications. So I have to figure I cannot get the modules to talk to each other. I can pull fuse F-3 in the pwr dist module and the crazy lighting stops. This circuit is the main power or a power circuit directly to the ECM (engine control module).

I'm thinking something is backfeeding somewhere and powering up circuits, or grounding the lighting circuits.

Have you guys seen anything similar, or have you seen a lot of corrosion problems on the engine ECM connections that have caused this?

This problem is pretty easy to reproduce, so it should be easier to find. This has been the first day I've been able to devote to it without interruptions,and armed with the laptop.

I'm new to C-2s so there is a learning curve I have to travel, figured maybe you experts could help me make it around the curve without getting off in the ditch!

Fastback
Top Member

1500 Posts

Posted - 04/03/2014 :  2:24:12 PM  Show Profile  Reply with Quote
What little I know about C2s is this, power is on to the multiplexed components all the time, the modules just switch on and off the ground circuit for the component. If something is not working, check and make a list of what else may not be working, then see if they are on a common fuse/circuit.

Why yes, the ORIGinal CHARGER is a Fastback
Go to Top of Page

tigger2
Advanced Member

USA
469 Posts

Posted - 04/04/2014 :  07:06:00 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
Look at the drivers side of the bus if your wiring loom is between the frame and the air brake lines, the loom is probably rubbed thru on the frame rails. Here comes the fun. We remove the wiring from the top of the fender and remove fender,in the frame rail where you cant see it is a ground stud that has a fat ground wire that is part of the loom reomve the nut with two swivels and a socket and pull the loom under the bus and repair ALL the rubbed through wires. Also look where the loom runs under the spring shackle end of spring and repair those as well. And while the fender is off check the back side of the fender to see if you have splitloom marks from vibration on it remove loom from those wires and repair as well. When you reinstall the loom rerout on the other side of the air lines so the main loom is behind the air lines, and re-clamp at sping end to clear that as well. When you re-attatch the small ground wires on the fire wall put all on the stud that has the ground wires inside the fire wall on it. This should end most problems, it has done well for us.
Go to Top of Page

BJ Henderson
Advanced Member

USA
280 Posts

Posted - 04/04/2014 :  09:19:51 AM  Show Profile  Send BJ Henderson an AOL message  Reply with Quote
Thanks for the info, tigger. I know a few months ago it was acting strange and I added a ground from the body to the engine and symptoms cleared up. At the time it was acting like the proverbial loose ground. Kind of like now.

Wasn't someone saying an AC Delco alternator could cause problems?

I did replace the alternator on this unit last year, but had no problems right after the install.Replaced the Leece Neivel with the AC Delco that crossed over to it.

CMTT,CMAT,CMBT
Go to Top of Page

BJ Henderson
Advanced Member

USA
280 Posts

Posted - 04/04/2014 :  09:26:30 AM  Show Profile  Send BJ Henderson an AOL message  Reply with Quote
Thanks Fastback, yes the switches on these things function the same as sensors on the engines, so the training material I have says.

I still for the life of me don't understand why everything needs to be passed through a module. I see more wiring for the same amount of work in the end on the newer buses. More to break and go wrong.

International is a little ahead since you are dealing with one info source for service. Seems to make it easier to chase problems. Not saying they are better buses, just a little more friendly to the mechanic seems like.

CMTT,CMAT,CMBT
Go to Top of Page

Fastback
Top Member

1500 Posts

Posted - 04/04/2014 :  12:30:13 PM  Show Profile  Reply with Quote
Its all great when it works; Pretrip lamp checks, backup lights illuminate the area when emergency door is open, dome lights on for a time after child check function is reset, etc.

Thanks to tigger2 for the great tips. I am going to make a copy this thread for future reference.

Why yes, the ORIGinal CHARGER is a Fastback
Go to Top of Page

Winn10
Active Member

49 Posts

Posted - 04/06/2014 :  10:28:45 AM  Show Profile  Visit Winn10's Homepage  Reply with Quote
to add to tigger2 reply, assuming this bus has the Mercedes engine, also the harness that is routed down by the P/S pump. the 90 degree fitting on the pump has rubbed through several of our harnesses. it is a PITA to repair and recommend not just "overlaying" the wire or using butt splices. after the repair shield harness with a piece of hose the prevent it from happening again
Go to Top of Page

BJ Henderson
Advanced Member

USA
280 Posts

Posted - 04/07/2014 :  05:42:57 AM  Show Profile  Send BJ Henderson an AOL message  Reply with Quote
Many thanks, guys. I will check this when I get a chance.

CMTT,CMAT,CMBT
Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
 


School Bus Fleet Magazine Forums © 2022 School Bus Fleet Magazine Go To Top Of Page
This page was generated in 0.06 seconds. Snitz Forums 2000