Hello all,

I have a 1999 Jamboree motor home built on an E350 chassis. It sat for several months without starting. I go to start it and discover that there is initial power to the dome light when the door opens but when I turn the switch nothing happens, no click from the solenoid, not even the three chimes normal upon turning the key on. The battery tested bad at the local autozone so I bought and installed a new one. Same thing happened. I also installed two new auxilary batteries that are part of the electrical system to power internal 12 volt lighting and accessories.

This RV comes with a swtch that allows the auxilary batteries to kick in and help start the motor if the main battery dies. That started the engine, I could drive it and everything worked from horn to radio, lights, turn signals,etc. As soon as I shut it off and tried to start it, nothing. I repeat the experiment and the engine starts with the auxilary batteries. This tells me that the switch is not sending power to the system to start and power the RV's electrics.

What needs to be replaced or fixed to solve this? A mechanic friend who lives in Arizona told me that the problem is not with the switch, relays or fuses but with some electrical component inside the steering column that activates upon turing the switch and powers everything. Does anyone recognize these symptoms and can point me to what I need to do to get up and running again?

Any help is more than appreciated

Thanks

 

This is a tough one to daognose over the internet without wiring diagrams for the modifications. If the aux battery switch is the only way the starting system gets power, then the aux batteries are connected to the starting system somewhere downstream of the main battery. The main battery circuit may have a bad cable, fusible link or other component that does not affect the aux battery connection. You (or someone) will have to trace the two battery circuits and see where the problem is.

My wild GUESS is the aux battery connects to the main terminals on the fuse box in the engine. The RED cable from the main battery to the starter solenoid is bad or disconnected. See attached diagram yellow highlight.

 

Hello Don,

thanks for your reply. I see how you're approaching this. The starter is not the only system affected however. Nothing works at all when the key is turned. No raidio, no lights, no courtesy light, no horn, etc. These are things that should be live by virtue of the fact that a battery is connected to the system. PLus the starter gets its juice from the solenoid which closes and sends the full amperage tto the motor. So wherever the auxilary battery cable goes to , that is the junction that is in question, it seems to me. The fact that all the systems go live when the motor is running tells me that the Alternator is running everything as it should. I did get an owners manual when I bought the RV but it doesn't show a wiring diagram only user manuals for the various components, like the microwave, the heater, the AC unit, the fridge, etc.

Now that you mentioned it, I'm going to see if I can contact the factory and maybe with the VIN number I can get a diagram or schematic. Thanks for your suggesitions and the diagram. That's real thoughful of you. I think you pointed me in the right direction. Even without the factory diagram, if I can trace the red wire from the auxilary batteries, that should take me to where the blockage is.

Thanks again,

 

Just a wild stab. Check the invertor/converter
I had a similar issue in my 89 Winnebago. Turned out the invertor/convertor 30amp fuse had melted.

Also double check the battery posts. Mine were not tightened and I drove the motorhome year round, water popped onto the connection and popped the wire off the post.

 

Other wiring diagrams show if the red wire I highlighted is not connected to the starter motor relay, nothing in the vehicle will get power. All those fuse links in the diagram feed the main fuse box (battery junction box) in the vehicle. A voltmeter and some quick checks will get you started while you wait for the modified vehicle wiring diagrams.

 

I suggest checking the terminal on the battery cables. I replaced a dead battery on my tractor last fall and the new battery would not even crank the engine. I had cleaned the cable terminal with a battery brush prior to installation but that was not enough. I recleaned it more aggressively with a sanding drum on a dremel tool until the inside surface was noticeably clean. This solved the problem. It made me think that I might not have had a battery problem in the first place but since the battery was 18 years old and used frequently (it had just started the tractor minutes earlier), I'm sure it was due for a change.

 

From this I'm hearing: Almost no power available to crank the engine.

From this I'm hearing: When there is power available to crank the engine, it cranks, starts, and runs fine.

From this I'm hearing: All the chassis stuff seems to work well, including the ignition switch.

All of this is probably running off the alternator and coach batteries. Chassis and coach batteries are usually isolated when the ignition is off and are all tied together when the engine is running so that the coach batteries get charged. This would also accidentally use the coach batteries as chassis batteries since they are all tied together.

Think of this: The coach manufacturer doesn't want a bunch of customers complaining that their coaches won't start. They install an isolation solenoid so that while camping, the chassis battery is isolated from the coach battery. That way the customer can run the coach batteries al the way flat and they'll still be able to start and charge and/or at least drive home. While the coach manufacturer is doing this, it occurs to them that they can easily add a feature that allows customers to tie the coach batteries to the chassis battery for the purpose of "jump-starting" a dead chassis battery. That's what you're doing to actually get yours started. Some people install the isolation solenoid to close when the ignition is turned on. I believe most RV manufacturers install this solenoid (or other solution that performs the same task) such that it won't engage until there is charge voltage coming from the alternator.

For your situation, first I'd check voltage at the terminals of the chassis battery with everything turned off. What is your reading here?

Then start it like you have been. Read the voltage at the chassis battery. What is your reading here?