C-13 shutting down, able to run when generator is running

[Eric Maclean Co-Admin]

Jim
On many of the Beaver coaches with vcat engines there is an ECM power supply relay , on the older coaches it was located in the back left corner of the battery bay not sure where it would be on yours ( that may be your problem)

Looking at the sciatica on page 105 of the 2007 Patriot wiring diagrams on coach assist the ignition relay is on board number 1 in the rear run box
The front /rear ignition control selector switch is also shown .
I have replace a couple of those front rear selector switch that failed ( they are usually exposed in a rear service bay with back open to the weather and road debris that and the fact they are rarely used leads to dirty connections inside and failure )
You may have either a failing front/rear ignition control switch or failing ECM relay.

Eric

[Scott Shearer]

Jim,

Circuit board #1 in the rear run box, the PCB that Eric is referring to, is a known failure point for the 2006 and newer Patriots and Marquis. When PCB1 is failing a “Eng Comm Failure" notification will be initiated, and the engine will shut down.

The remote start and front/rear selector switches are mounted on this board.

Search for this, “2008 Navigator; Intellitec 73-00825 rear run box board bad. Workaround?” and you’ll find some troubleshooting and workaround suggestions. Also, suggestions for repair of PCB1.

Circuit board # 6, rear run box. When the ISO LED is illuminated it is indicating that the Big Boy relay is energized. Even when no charging is taking place, the Big Boy will remain energized until the surface charge of both battery banks has dissipated, both battery banks must drop below 12.8-volts. This can take several minutes depending on the 12-volt load.

Look at “Coach Assist->Common Problems->Battery Charging Systems” for a good explanation of the operation of PCB#6.

-Scott

[Jim Hosler]

AWSOME information Eric and Scott!

Scott The owner and I trouble shot it together yesterday and we came up with a switch power to the ECM as an additional connection so if it dropped from the boards the ECM would stay hot and not drop out. Your post helped me walk through the issues and they almost perfectly matched and he was going to check that board out and get back to me.
I am going out of town, so they are going to shut everything off and let it cool down and drain power from the boards and then see if they can get the problem to duplicate so they can positively identify the failure. Also, the generator may have just help with additional power but, we were also pushing on that switch trying to get it to run and it may have just made the connection.
I will update you all late next week. 
I will be happy to buy you both a cold one for this!!!