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Topic: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL? (Read 1975 times) previous topic - next topic

Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

My generator starts but stops when you let off the switch.  I thought I had it fixed but it has reappeared.  The service manual that Barry emailed (Thank you!) me suggests that the problem may be the low oil pressure switch but does not show its location.  Any one know where it is located?
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #1 –
I had a similar problem on my previous SOB.  It wound up to be the voltage regulator which is a very common problem on the Onan Emerald  series.  Look at the run circuit on your schematic. The voltage regulator supplies the plus, and the oil pressure supplies the negative.

Joe Gauntt
Maple Valley, Wa

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #2 –
An update-

I finally had a chance to check out the oil pressure switch today.  The first problem I ran into was the manual that Barry had emailed me did not match the unit.  I discovered  that my unit is Specification G, while the manual is Specification A thru C and it seems there have been major changes to the control system.  The general layout was similar however and, more importantly, the wiring is imprinted with the to and from locations on it!  After struggling with getting the cover off the left side head (a bolt was so frozen the head broke off when I tried to loosen it), I removed the wire from the oil pressure switch, cleaned it and tried to run the generator but still had the same problem.  I took a wire and stuck it in the connector and grounded it but it would still not run once the start switch was released.  I will go through the rest of the troubleshooting chart when I get the GV home.  As long as I am checking the unit I thought I would hook up an oil pressure gauge - does anyone know what the oil pressure should be?
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #3 –
First check is to put a Volt Meter on the AC output, check to see if the output voltage is above 90 Volt AC. 
if not, the voltage regulator is the issue
If you the voltage is more than the 90 VAC, the issue would be the control brd.

Without a meter and without checking is is not possible to tell what is what.
Will send Barry a manual for your spec.

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #4 –
Dave,

Thanks! BTW, what do the W1 and W2, refer to?
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #5 –
  I do not have the wiring diagrams open so can not tell you, as for as the the oil pressure switch, it is located above the oil filter next to block.

The reason for sending the manuals to Barry, seems he has been appointed keeper of the paper work for Foretravel items, so felt that should be in his  library.  :)

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #6 –
You asked about W1 & W2,  leave them alone, if W2 is not connected, DONOT contect to anything. It has to do with neutral, so leave it alone and do not try to out smart the engineers on this one.  It is not your problem.

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #7 –
I recently had the same problem. The gennie motor would run as long as the starter switch was pressed and die whenever the switch was released. I finally took it to Onan and it was the Voltage regulator. Cost was about $400 with labor. Part was about $300.Sorry to be the bearer of bad news but if you go back through the posts related to the Emerald starting and dieing, you will find it is most likely the voltage regulator, the second most frequent is the control board.

I took the position that if I was dealing with parts as expensive as the Voltage Regulator and Control Board, it was wise to take it to the Onan repair center to make sure the correct part was replaced.

By the way, there are very few people in the country that know more about generators than Dave M.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #8 –
Dave,

I was not planning on doing anything with them, I just had never seen symbols like these in a schematic before and did not know what function they performed.  Are they jumpers?  It sure looks like W1 would have to be connected or the start switch would never ground the K4 relay.
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #9 –
I do not have your wiring diagram, so since you have it and you understand how it works, seems like a time for a choice.
Will take a look this evening when have time.

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #10 –
John,
I have gone over the manual, can not find anything concerning the W1 wire, however the W2 is described.  You will need to read the service manual in detail, there is a lot of info there, most is boring but you will find what your after with careful reading, Gives good trouble shooting chart etc.
There are many wiring diagrams in the manual, however I can not locate one with the W1 wire, this is an indicator there are many different ways to wire the unit, and usually when one is different, it is due to the buyer having some different requirements, so Onan does what is needed to sell the unit.
It is nice they silk screen the actual wiring diagram on the unit.
If you provide the actual wiring diagram #, I can get it and see what is up.
You will find Onan/Cummins makes many models that fit many requirements, so careful reading and understanding is a must.
I would not get creative. Wreckless experimenting usually ends with a big price tag. :o
Cheers

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #11 –
Dave,

The original manual I got from Barry was for Spec A-C and the schematic of it on page 7-9 shows a W1 between the K4 relay and the start position on S1.  W2 shows up between the negative side of the battery (ground) and the B2 side of the generator which also goes to P1-7.  I was not planning on doing anything with them, I was curious as to what they represented.  On close examination with a magnifying glass they sort of look like switch contacts except the line going between them does not complete the circuit.

I cannot see anything similar in the schematic for the Spec G version but then the schematic is so poorly done that much of the smaller print is unreadable. The control board check-out section hopefully will help me figure out what is going on.
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #12 –
Problem solved!  It appears that one of the remote start switches was stuck in the stop position.  Today I finally had a chance to get back and spend some time on this problem.  I double checked the oil pressure switch after replacing the blown 5 amp slow blow fuse - I was lucky in that I had three of them in my spare parts that I kept when I was dismantling computers for fun and profit.  Shorting the wire from the oil pressure switch to ground made no difference.  I had sprayed all the connectors with CorrosionX or Corrosion Block and it did not help.  I had a WAG and decided to remove the connector for the remote start function and the generator kept running after letting go of the start switch.  Tested it several times and it continued to work so I then went inside and toggled both remote switches several times, plugged the remote cable back in and every thing was working properly.  I am sure glad it was that simple.
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Where does the oil pressure switch hide on an Onan Emerald IIII NHEL?

Reply #13 –
Yup, common sense and good luck go a long way in solving the most difficult problems.
Congrats :)