Calling all electrical system sleuths

simionsen wrote:
I have a 2007 Itasca sunova 35J

house batteries charge when on shore power as well as when the generator runs, but not when driving.
In a small compartment to the right of my steps are the two items. On the left in this compartment I have a silver battery solenoid isolator. I changed it out for a new one. It still does not click and doesn't charge my house batteries. To the right of the isolator is the battery disconnect. It does seem to be working. It clicks on and off and does disconnect the house batteries. I would post a pic, but not sure how to. I have checked the fuse on the relay and it is not blown. I don't want to take it in if it's any easy fix that I don't know about. Thoughts please.

David

The Battery Mode Solenoid can be seen on page 2 of the Body, 12 Volt Wiring Diagram for your coach. It is controlled by the yellow wire labelled LR. When that wire supplies 12V to the solenoid it will close, connecting the two battery banks together.

The Wiring Identification Guide provides info about that wire:

LR / 14 YEL BATTERY MODE SWITCH (AUX START SWITCH) BATTERY MODE SOLENOID (AUX START SOLENOID)

The lower left corner of page 8 of the Automotive Wiring Diagram for your coach shows the wiring harness for the Battery Boost switch on the front panel. It has three yellow wires connected to it, labelled LR, LS, and KE. Here's the info from the wiring identification guide for the additional wires:

LS / 12 YEL OVERCURRENT PROTECTION 20A BREAKER TYPICAL,COACH FEED GENERAL PURPOSE(BATTERY MODE, RADIO POWER,BATTERY CONDITION

KE / 14 YEL RUN ONLY POWER SOURCE GENERAL PURPOSE(RELAY TRIGGER, REAR AUTO HTR,DRL,MONITOR,ETC

Normally the Battery Boost switch connects KE to LR, which means that the Battery Mode Solenoid should be closed whenever the engine is running and open when it's not. When the Battery Boost switch is pressed it will connect LS to LR, causing the Battery Boost Solenoid to be closed as long as the switch is held.

If you have a Ford Chassis, looking in the upper right corner (location D-1) of page 2 of the Automotive Wiring Diagram you can see that KE connects to the ACCESSORY FEED #2 RUN ONLY in the chassis-supplied wiring harness. If you have a Workhorse chassis, looking in the upper right corner (location D-3) of page 5 you can see that KE connects to pin C7 in the Workhorse I/P Convenience Center.

Since you indicated in a subsequent post that the Battery Boost switch doesn't seem to be working either that would indicate three possible problems:

• Defective Battery Mode Solenoid
  
• Bad wire LR between Battery Boost Switch and Battery Mode Solenoid
  
• Defective (or unplugged?) Battery Boost switch

If you have 12V at the terminal on the solenoid where LR is connected when the engine is running and when the Battery Boost switch is pressed then the problem is presumably the solenoid--replacing it should fix things up.

If you don't have power at the terminal then you'll need to make your way back towards the switch to figure out where things are going wrong.

Dale.Traveling wrote:

simionsen wrote:
,,, The battery boost switch doesn't do anything when pushed. I was under the impression that it should cause the isolator to open (click). So perhaps the problems is there somewhere.

You're getting close. Actually when you close the switch the isolator will close connecting the two battery banks together. For charging either when on shore power or when going down the road that isolator (aka solenoid) will close.

Now the question is what is common that is needed to close the circuit either manually with the battery boost or automatically to cross charge? Wish I knew more concerning how Winnebago wired up the circuit to provide guidance on what to check next. The theory is pretty much the same but individual application can be different between builders.

Actually the solenoid doesn't close when on shore power, only when ignition is switched on or the boost switch is activated.

just double checked and the wires going to the engine battery from the alternator are at 14 volts so the engine battery is charging. Since I am no electrician looking at the diagrams are somewhat useless haha

simionsen wrote:
,,, The battery boost switch doesn't do anything when pushed. I was under the impression that it should cause the isolator to open (click). So perhaps the problems is there somewhere.

You're getting close. Actually when you close the switch the isolator will close connecting the two battery banks together. For charging either when on shore power or when going down the road that isolator (aka solenoid) will close.

Now the question is what is common that is needed to close the circuit either manually with the battery boost or automatically to cross charge? Wish I knew more concerning how Winnebago wired up the circuit to provide guidance on what to check next. The theory is pretty much the same but individual application can be different between builders.

enblethen wrote:
DVM, Digital Volt Meter.
Look on your dash for an "aux" start switch. The relay used for that function is the same as for battery coach charging system.
I would guess that there is no power through the battery control center to operate functions. Look at fuse panel for appropriately named fuse.
Online Drawing 154491 shows circuit breakers and not fuses.

The OP said

"Not sure what a dvm is, but I have access to the schematics. The battery boost switch doesn't do anything when pushed. I was under the impression that it should cause the isolator to open (click). So perhaps the problems is there somewhere."

So he has tried the "aux" start switch and it does nothing. It is probably a fuse in an ignition controlled circuit, probably part of the Chassis Fuse Group under dash, might be the same fuse as 12 volt power receptacle.

DVM, Digital Volt Meter.
Look on your dash for an "aux" start switch. The relay used for that function is the same as for battery coach charging system.
I would guess that there is no power through the battery control center to operate functions. Look at fuse panel for appropriately named fuse.
Online Drawing 154491 shows circuit breakers and not fuses.

Not sure what a dvm is, but I have access to the schematics. The battery boost switch doesn't do anything when pushed. I was under the impression that it should cause the isolator to open (click). So perhaps the problems is there somewhere.

If you believe that the left solenoid is the isolator solenoid (and that sounds very likely to me), the next step would be to make sure it's getting a proper control signal. Check the voltage of the thin wire going to the control terminal (or across them, if there are two such terminals). You should see power there when the engine is running, possibly after a delay depending on the exact setup, and when the emergency start switch is activated if you have one.

If you have power at the control input when you ought to but the relay itself isn't activating, then the relay is bad. If you have no control signal, then the problem is likely not the relay but something upstream from it. If you have control power only when the emergency start switch is activated, then there are a couple of possibilities: your motorhome could be wired such that the isolator is separate and doesn't use this relay, or you could have some problem with the isolator control signal. This signal is probably wired through the emergency start switch, and might be able to be traced back from there.

The nice thing about Winnebago/ Itasca is that all shop drawings are avaliable online. You should download yours and keep them handy. What you need to decide is if you have a diode battery charge isolator or contactor relay doing the charging. The drawings will show that.

But without a DVM you can troubleshoot nothing... Do you?

Workhorse or Ford chassis?