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Generator indicator light and hour meter - connected?

A couple months ago, our dash indicator for the generator (single green LED), stopped working after the dash switch was pressed "off" and the on -generator switch had stuck slightly in the "start" position.  I posted about this but had no responses.  I noticed a few days ago that the generator hour meter no longer works.  Neither the LED nor the hour meter are getting power.  I would assume the hour meter would run from 12-volt.  The LED would likely be less, but might have a resistance wire to drop the voltage.  I did not see a resistor nearby.  I looked at my wiring diagrams, but I did not see any of this on them.  I also would assume that they LED and the hour meter are symptoms of the same cause.  The generator starts and stops fine from the dash switch or the service switch.

Any ideas for the quick fix, or where to start looking?

oldMattB

Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #1
I don't know if it's true in this case, but most hour meters are switched on by oil pressure via a mechanical pressure switch on the side of the engine.  The light might be powered on the same circuit.  Just an idea.  I had this switch go bad on main engine (DD 6V92) a few years ago.  I picked up a generic replacement from McMaster-Carr catalog.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Generator indicator light and hour meter - connected?

Reply #2
That would make sense.  If I remember correctly, the light does not come until the generator starts.  Cranking does not do it.  I will look for the oil pressure switch and check it.

Any other opinions?

oldMattB
Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #3
The oil pressure switch is working properly.  Any other ideas?  How does the generator create a 12-volt source for the LED and for the hour meter before the AC power is available?

oldMattB
Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #4
Matt,

Not sure which generator you have, but mine and probably most RV generators get 12 vdc from the house batteries for the starter and other functions.  My generator does not have an alternator installed on the engine.  The 120 vac it is making when running goes to an inverter/charger or converter which recharges the house battery.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Generator indicator light and hour meter - connected?

Reply #5
Went up there and forgot to look.  It is an Onan green thing that runs on propane, maybe an Emerald or something?

I know the generator uses the coach 12-volt to start.  Immediately after it starts and before the 120-volt power is available, it apparently supplies 12-volt to the hour meter and to the indicator light on the dash.  The light is the important one for me.  With the engine running, there is no way to tell when to let go of the generator start button, unless the light is functioning and comes on.  There is a delay of 10-15 seconds from when the generator starts until the 110-volt ac is supplied to the coach.

I am confident that the hour meter and the indicator light are wired together, and there is probably a bad fuse or something, but I have no idea where the wires run or where to look for the problem.

oldMattB
Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #6
 ???  It's funny that this subject came up at this time, because on my trip up north yesterday, that little green indicator light for my generator stayed lite after the generator quit running. I could not figure out why it would continue to have power when there was no power source??  It did go out after a short while. 
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Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: Generator indicator light and hour meter - connected?

Reply #7
Like everything else hour meters sometimes go bad.  Like others have said the meter and light probably work off 12 vdc.  Is the meter getting power when the generator is running?  If so you might also disconnect it electrically and apply a 12 vdc source to see if it runs. The house battery would still provide 12 volts to the control wiring after the generator starts and is running.  An hour meter is just an electric clock that records time rather than telling time.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Generator indicator light and hour meter - connected?

Reply #8
No power to the hour meter and no power to the indicator LED.

oldMattB
Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #9
Try checking the fuses on the genset control panel, the DC feed for the hour meter and run light go thru qa fuse as I recall on terminal 5 & 6, guess I need to look at the diagram again been too many years since last look see, but take a look at your wiring diagram.  However without the CORRECT model and spec info it is a crap shoot trying to get the correct controller diagram as there are more than one possibility.
SO a little digging on your part will make it all possible, tnx.

Re: Generator indicator light and hour meter - connected?

Reply #10
Do you mean the panel with the interior switch and indicator light?  My FT has the switch and light built into the dash.  I tried following the wires from the dash and from the gen, but both quickly got lost in the harnesses.  I looked at the fuse panels in the dash and could not find a gen related fuse.  I checked all of the inline holders I could see.

There is a second switch in the bedroom - could the fuse be behind it?

oldMattB
Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #11
THINK GENERATOR  not all the possibilities, keep it simple, look at the generator control panel

The generator control that is mounted on the generator set.

Re: Generator indicator light and hour meter - connected?

Reply #12
Matt,

On my Emerald III there is a connector on the right hand side of the control panel that is the connection to the remote switches.  It is possible that there is just a bad connection between the control panel PCB and the connector.  Remove the connector and clean/lube it.  Put it on and remove it several times to wipe the contacts.  Dave M is right about the pins for the meter and the LEDs, at least on a Spec G version.  If yours is later then it may be different. See the photo of the model number showing the G at the end.  That is the Spec version (revision).
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Generator indicator light and hour meter - connected?

Reply #13
Like everything else hour meters sometimes go bad.  Like others have said the meter and light probably work off 12 vdc.  Is the meter getting power when the generator is running?  If so you might also disconnect it electrically and apply a 12 vdc source to see if it runs. The house battery would still provide 12 volts to the control wiring after the generator starts and is running.  An hour meter is just an electric clock that records time rather than telling time.

After I posted this I realized that some clock motors also operate using 120 vac and are regulated by the 60 hz frequency.  Anyway the hourmeter may or should say what power it takes whether ac or dc.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Generator indicator light and hour meter - connected?

Reply #14
RV Onan uses DC hour meters, If he would get the model info . it would be so simple to answer , with out WE are ALL GUESSING There are some variations in the controls, why proper info is real nice.

Re: Generator indicator light and hour meter - connected?

Reply #15
MATT, If you would take a good picture of the control and generator,  the control can be determined OK?

Re: Generator indicator light and hour meter - connected?

Reply #16
Photos of generator, generator id plate and generator master panel should be attached.  The fuse on the front of the panel is good.  There appears to be no fuses inside the control box.  I looked for loose and corroded connections and found none, though some are really tough to get to.

The molex connector on the side has wires numbered 1, 2, 3 and 4.  Each has two wires attached, which I would guess  to be for the two remote starting switches - one at the helm (with LED indicator) and one in the bedroom (no LED).  When the generator is running, wires 1 and 2 showed 12 volts, 1 and 3 and 1 and 4 showed 14 volts.

oldMattB
Matt B
1998 u-320

Re: Generator indicator light and hour meter - connected?

Reply #17
Matt, Later this evening I will post the service manual for this unit, having the model info just makes it all possible, there are about a dozen manuals that could cover this series, as it it has been a round many years and many changes etc, so thanks for the data.

Re: Generator indicator light and hour meter - connected?

Reply #18
OK Matt, Dont get into trouble with this  :)
This should answer any questions you have concerning your Onan Generator

 

Re: Generator indicator light and hour meter - connected?

Reply #19
Manual was VERY helpful.  Problem appears to be an "open" resistor on the control board.  The manual does not give a value for it, but maybe I can get a value directly off the resistor.  I am sure Onan would like me to have them replace the entire board for me.

The hour meter and the indicator light are run parallel to starter wires 1 and 4, wires 5 and 6 apparently not present when the factory remote panel is not used.  The manual suggests a short in the hour meter or indicator light as the cause of the resistor failure, but in my case, I believe it was both switches being activated at the same time (the switch on the generator was stuck in the on position - not enough to engage the starter, but apparently enough to energize the other wiring).

I don't like board-level repairs - I like big, wrenchy stuff!

oldMattB

... and I am surprised Onan didn't have a provision to fuse wires that were meant to go elsewhere, instead of a malfunction burning up components on a pc board.
Matt B
1998 u-320