I was on my way back from a trip this weekend and i discovered that my Onan Gen Set 7500 will not start. I have a full charge on the battery and all breakers are good (solid on / solid off). Is there something I am missing. It is definitely something electrical because I get zero power. When I left for my trip, it was working. I never used it during the trip because of the cool temperatures. I turned it over when I reached my destination just to check and it worked fine. On my way back home, (at night) I tried to start it for lighting and....nothing. On another odd note, my fridge wouldn't even work on the LP gas setting. Is this because it requires voltage to switch it? Any help would be appreciated.If it helps, I have a 96 Winnebago Vectra Grand Tour, Cummings Diesel, Allison Transmission and a Freightliner (Osh Kosh) Chassis.

Did the refer also work when the trip started on LP and then quit during the trip like the generator. Yes the generator is diesel, but I'm wondering if the the 12V power to both of them quit during the same trip.Bill

Are you getting any 12 volt in the coach? Is the propane tank full? Is the cook stove working? Not knowing if your fridge shows fault indicators? Do you know if the Gen runs off the chassis or house batts? Can you grt to the gen starting solenoid to beable to jump from in to out terminal ... indicating if your getting juice?

It does sound as though you do not have 12DC in the coach... and yes your gas absorption refrigerator requires 12 DC. Can you verify that your its your house battery(s) that are fully charged are fully charged?

Ccoddou wrote:I was on my way back from a trip this weekend and i discovered that my Onan Gen Set 7500 will not start. I have a full charge on the battery and all breakers are good (solid on / solid off). Is there something I am missing. It is definitely something electrical because I get zero power. When I left for my trip, it was working. I never used it during the trip because of the cool temperatures. I turned it over when I reached my destination just to check and it worked fine. On my way back home, (at night) I tried to start it for lighting and....nothing. On another odd note, my fridge wouldn't even work on the LP gas setting. Is this because it requires voltage to switch it? Any help would be appreciated.If it helps, I have a 96 Winnebago Vectra Grand Tour, Cummings Diesel, Allison Transmission and a Freightliner (Osh Kosh) Chassis.As I posted earlier but it seems to have been lost.It sounds like you have inadvertantly shut off the 12V disconnect switch.This will account for no 12v lites,no fridge power and No gen battery powerits usually in the stairwell area of th MH

How cold is it outside? Diesel genset has glow plugs. You might have to hold the start switch for several minutes before it will crank. Fooled many a man.

Onan Gen Set 7500 Diesel | Good Sam Community

Big_Katuna
Explorer II
Oct 23, 2013
But it will still crank.
cbeierl
Explorer
Oct 23, 2013
The generator fuel intake in the fuel tank is placed at approximately the 1/4 tank level so that you can't run yourself out of fuel with the generator.
Ccoddou
Explorer
Oct 23, 2013
sprinter293 wrote:
I have that same Generator and as a safety feature it will not run or start if the diesel fuel tank is under a quarter.

Hopefully it is something simple.

That was the first thing I thought of because my old class C had the same feature. However the tank was 2/3 full when it wouldn't start. When I finally got it started, the tank was showing less than 1/4 tank. Hopefully the gauge is inaccurate and mine has this same feature. I will run the tank low this weekend and see if it shuts down on its own.
cbeierl
Explorer
Oct 23, 2013
Ccoddou wrote:
Well I managed to tinker long enough to get the generator to start. My best guess is that I hit a combination of switches and disabled it. Wish I knew how to do it on purpose to save my battery. What I did was press the AUX battery and AUX start buttons in conjunction with the generators start button and it fired up like a champ. I ran it for 5 minutes...turned it off for 5 minutes and it fired right up. I am even getting the backlight on the switch. Not sure I know what the problem was but I know the solution if I ever encounter it again. Thanks for the help

I think your AUX Battery switch is your house battery cutoff switch. The AUX Start switch should connect your house and chassis batteries together as long as the switch is held down.
Ccoddou
Explorer
Oct 23, 2013
Well I managed to tinker long enough to get the generator to start. My best guess is that I hit a combination of switches and disabled it. Wish I knew how to do it on purpose to save my battery. What I did was press the AUX battery and AUX start buttons in conjunction with the generators start button and it fired up like a champ. I ran it for 5 minutes...turned it off for 5 minutes and it fired right up. I am even getting the backlight on the switch. Not sure I know what the problem was but I know the solution if I ever encounter it again. Thanks for the help
sprinter293
Explorer
Oct 22, 2013
I have that same Generator and as a safety feature it will not run or start if the diesel fuel tank is under a quarter.

Hopefully it is something simple.
FIRE_UP
Explorer
Oct 22, 2013
iamalienru wrote:
I have a 98 onan quiet it runs off the chassis battery. I was having intermitten starting from the start button inside the coach. On the back side of the gen it has 2 power cables coming into the gen. Mine were semi corroded causing the start problem. I would diconnect them and make sure they are nice and clean. Check and see what type of power in coming in to the gen.

This was going to be my input too. While you may have a solid 13V at your batteries, down stream you may have a "break down" of some sort. Maybe like jamalienru had, some corrosion on terminal, or connection point, a really bad ground, corrosion inside the cables etc. Since you've checked all the switches/fuses etc., then I'd maybe head on over to the "bad cable/connection/ground" side of the investigation to see where it leads you. Good luck and please post back what you find as the problem so that others may learn.
Scott
Ccoddou
Explorer
Oct 22, 2013
cbeierl wrote:
According to the Front End Wiring Installation diagram for your coach (page 11 of the pdf) the Coach Battery Disconnect switch is the lowest of three switches on the left side of the instrument panel, below the Radio Power and Aux Start switches. If that switch has been turned off that would kill the 12V power to the coach.

I see the switch you are talking about but unfortunately my vectra does not have this switch. All of my switches are vertical on the left and right side of my instrument cluster. There are no pre-existing holes in that location that would indicate that there was ever a switch either. I sure wish it had a battery disconnect though. it would save a lot of future battery charges. Thanks for the input though.
iamalienru
Explorer
Oct 22, 2013
I have a 98 onan quiet it runs off the chassis battery. I was having intermitten starting from the start button inside the coach. On the back side of the gen it has 2 power cables coming into the gen. Mine were semi corroded causing the start problem. I would diconnect them and make sure they are nice and clean. Check and see what type of power in coming in to the gen.
cbeierl
Explorer
Oct 22, 2013
Btw, if you go here Winnebago Wiring Diagrams and select your coach year and model you'll see full wiring diagrams for your coach.