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Ask Hank F. Your Own Question
Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 14488
Experience:  RV tech since the beginning of the millenium.
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My onan generator won't start. the code in book says low

Customer Question

my onan generator won't start. the code in book says low voltage. have checked batter and cleaned all cable ends. the generator is a onan 4000. the motor home is a class c jayco grayhawk. the coach is a 2005 ford 450 with a v 10 engine
Submitted: 1 year ago.
Category: RV
Expert:  Randall replied 1 year ago.

How did you check the voltage? Surface voltage like you can measure with a multimeter won't give you the real condition of the batteries. You need to have them load tested and checked for shorted cells. Most places that sell batteries have a tester for that. If these are over 3 years old, there is a good chance they need replacing. Don't forget to clean the ground lead to the chassis. That can be a source of problems with low voltage. Hope that proves helpful here. Please get back to me if we need to do more work on this as all follow us are included in our fee.

Customer: replied 1 year ago.
I had the battery tested at auto zone store. batter is less than 2 yrs. old. cleaned both post on battery but not where the ground wire is fastened to the chassis.
Expert:  Randall replied 1 year ago.

I would do that then........and one thing we do in the shop when we suspect the battery is to hook up an external source OR have the battery getting some additional charging to be sure we eliminate that as a cause of the problem. It can be a start solenoid that has dirty connections OR is failing due to burned contacts internally. Checking for the incoming DC voltage on BOTH sides of that can be an indication.

Customer: replied 1 year ago.
I have to leave the house now to attend to my business. I feel that I have tried everything you have spoken of so please do not call this number at this time for I will not be there and my wife would not be able to help with this need.
Expert:  Randall replied 1 year ago.

10-4...........I will make a phone offer for you and let me know when is a good time to chat.

Expert:  Randall replied 1 year ago.

Our Onan tech on site says there is no "Low Voltage" code on that set............are you sure you read it correctly?

Customer: replied 1 year ago.
the light blinks 3 times and then 2 times and the book I have said that was low voltage. so I don't know any more than that. when I try to start the generator it just makes a one time click noise and nothing else. then the light on the button starts blinking fast. when I push the stop button it blinks 3 times and 2 times until I push it again.
Expert:  Randall replied 1 year ago.

That fault code is actually a "Low Cranking Speed" fault...........and that can be a result of the battery issue I gave you earlier. Did you try another outside power source for the starting? Or have the coach plugged into shore power so the battery can be charged (if this is the house battery). Try that and get back to me.

Customer: replied 1 year ago.
sir the motor home is connected to house power and I also tried starting the engine of motor home. I also tried jumping it with my Tahoe. I even jumped the Tahoe to the solenoid of the generator. results the same.
Expert:  Randall replied 1 year ago.

O.K...........I will opt out of this and hopefully, one of our techs who is great with Onan sets can jump in and assist you. He is pretty busy, so be patient. Thanks!

Expert:  Blake Pankratz replied 1 year ago.

I can provide you with a service manual if that would help you. I will need your full model number however.

Customer: replied 1 year ago.
no thanks. I have a operators manual and an installation manual. the model # ***** ***** and the S.N. is k030571019
Expert:  Blake Pankratz replied 1 year ago.

okay.

Customer: replied 1 year ago.
is there any help for me now. or are we through
Expert:  Blake Pankratz replied 1 year ago.

Other than providing a service manual I can not be of any more help on this issue. My apologies.

Expert:  Hank F. replied 1 year ago.

Hello, my name is ***** ***** I am going to assist you with this.

I am actually a cerified Onan technician.

The first thing I need you to do is to connect an AC voltmeter to the output leads of the genset.

Press and hold the start button for a few seconds to keep the engine running.

What voltage reading do you get?

Customer: replied 1 year ago.
Hank I have taken it to a Mechanic now. I thank you for responding but I must wait to see what these people find. thanks again
Expert:  Hank F. replied 1 year ago.

OK

.