Jump to content
jimr

Regulator Wiring Diagram

Recommended Posts

jimr

Hello and thank you for letting me join.

 

I am repairing this 520H for my neighbor. I have no idea of the age but he thinks it is quite old.  The hour meter has stopped working may hours ago.

The initial problem was pulsing of the throttle with little fuel showing in the filter.  I temporarily bypassed the fuel pump and installed an electric pump.  The pulsing was eliminated and the filter shows 'some' fuel.  I have ordered a 12 volt fuel pump.  During the pump install I checked the battery voltage.  It was 12.2 volts and did not vary with any engine speed. During the wire tracing of the charging circuit I broke the Red wire on the regulator.  A new one will be here Thursday along with the fuel pump.  I am hoping the new regulator will correct the charging problem.

 

The owner has given me a copy of the user manual but the electrical schematic does not cover the charging circuit.  Does anyone have this portion of the wiring diagram?  Also on the wiring diagram I have, it shows a 30 amp fuse going to the engine.  I found two fuses on the frame, one 10 amp and one 20 amp.  Where is this 30 amp fuse located?

Lastly, the manual states adjustment of the carb to control the mixture.  I have looked repeatedly around the carb and have not located the idle adjustment screw.  Is it buried under some accessories? This has an Onan P220G engine.

 

Thank you in advance for any help or suggestions.

 

Regards,

Dan K.

 

 

Share this post


Link to post
Share on other sites
 
gwest_ca

1988-89

1990

1991-1997

Engine service manual

Garry

Share this post


Link to post
Share on other sites
 
WHX??

:WRS: Jimr you certainly came to right place for help.

Be sure to check all grounds and the nine pin connector behind the engine and the fuse holders for any issues.

On the fender pan should be a decal, get us those numbers and we can nail down the year.

  • Like 2

Share this post


Link to post
Share on other sites
 
953 nut

:WRS:

As Jim said, cleaning and tightening ALL electrical connections including grounds will solve most problems. Your voltage regulator has three terminals. The two outside terminals are connected to the alternator in the engine, they should read 30 +/- volts AC with the engine running. The center terminal is the output terminal and should read battery voltage with the key on and not running and higher that battery voltage when running.

Share this post


Link to post
Share on other sites
 
KC9KAS

@jimr :text-welcomeconfetti: to :rs:

Share this post


Link to post
Share on other sites
 
ol550

Some 520 models had the third fuse at the starter.

Share this post


Link to post
Share on other sites
 
jimr

Thank you all for the links to the documentation.  Reviewing these pages, some have a 30 amp fuse on the output of the voltage regulator.  Can someone provide a location for this fuse?

The new regulator should be arriving today along with the electric fuel pump.  I wil check the wiring from the regulator to the switch but if the 30 amp fuse is blown, trying to find it maybe the bigger challenge.

 

Thanks again

Dan K.

Share this post


Link to post
Share on other sites
 
WHX??

Should be located in the fuse block on the upper right side of the hood stand. This is if it hasn't been relocated the factory fuse holder has been known to be problematic with overheated and bad fuse holder terminals so a PO may have moved it. As can be see in the pic dirt, water and debris can get in there and mess things up. The fourth slot for a fuse should be factory empty.  There is cover made for these but don't think they came from the factory with one.

20180421_150027[1].jpg

Edited by WHX21
  • Like 1

Share this post


Link to post
Share on other sites
 
jimr

Thanks for the picture but this tractor does not have this multi fuse holder.  There is one holder below this location that has one 10 amp and one 20 amp fuse.  Both of these were checked to be good.  I guess the best course of action is to trace the wiring from the regulator output to the switch  UGGG!

 

Regards,

Dan K

Share this post


Link to post
Share on other sites
 
WHX??

Yup ..someone's been in there before then. There often isn't much wiggle room in the wiring harness to repair the fuse block so lowering it is an option to gain more wire. Trace out the center B+  wire from the regulator through the nine pin connector. Should go right back to the battery via a 30 amp fuse. In the connector  that pin and the pin with the red wire are usually the culprit in the connector. You can see the orange wire nuts in the pic where a PO has already bypassed these out of the connector.

Capture.JPG

Edited by WHX21

Share this post


Link to post
Share on other sites
 
jimr

Thanks, can you provide a link to the diagram you attached.  This is more descriptive than any I have.

 

Just wish it were a little warmer than 25 degrees in the garage!

 

Dan K

Edited by jimr
update

Share this post


Link to post
Share on other sites
 
ol550

The original fuse holder was replaced with a weather proof one. orange wires

 

IMAG1513.jpg.024136cc7726adfda25b7fe9ee2c4bc3.jpg

usually clipped to the air shroud

Edited by ol550
more info

Share this post


Link to post
Share on other sites
 
WHX??

It's in the manual listed above but here is one for later models. Be careful as the wiring did change abit from late 80s to 90 models. That's why it's kinda important to know the exactly year you are working on.

2 hours ago, jimr said:

a little warmer than 25 degrees in the garage!

It's 68 in mine.... :lol::hide:

Later model 520 wire diagram.pdf

Share this post


Link to post
Share on other sites
 
jimr

Well I found the 30 Amp fuse near the starter relay.  It was blown.  So I replaced the fuse and installed a new regulator. Started the engine and checked the battery voltage.  It was 12.12, no charging.  Checked the input to the regulator and it was 36 volts AC so that looked good.  Looked at the fuse and it again was blown.  Removed the Batt lead from the regulator with a new fuse and the ground wire of the battery disconnected, turned the switch to ON and measured the resistance.  It was 13.5 ohms so that would indicate about a 1 amp draw.  Re installed the negative lead of the battery and disconnected the Positive lead of the battery and inserted an ammeter.  Sure enough it was around 1.2 amps.

I am thinking the new regulator was bad and had an internal short which took the battery voltage directly to ground through the 30 Amp fuse.  I can not figure any other explanation.  

I just completed another test.  The resistance of the Stator from the Red lead to ground is 37 ohms, the White lead is 30 ohms to ground.  These readings are with the regulator removed.  Do they seem correct?

Any thoughts I should look into.  I already have started a return and replace with Amazon for a new regulator.

 

Dan K.

Share this post


Link to post
Share on other sites
 
WHX??

I would have checked the regulator (center post) for 13.6 to 14.6 volts DC with the engine running and fuse out or center post disconnected . Would be very unusual for one to bad out of box but not impossible.

1 hour ago, jimr said:

and it was 36 volts AC

Sounds about right at mid to WOT. So that tells you right there the stator is good. Recheck the wire from the regulator through the fuse and right back to the batt for chafing or rubbing and shorting out.

Share this post


Link to post
Share on other sites
 
jimr

Checking again the resistance of the stator leads to ground I found 1.3 and 1.2 ohms.  If the charging current is anywhere near the 20 amp region then I would suspect this is about correct.  Any higher internal resistance would develop a large internal voltage drop.  I even connected a battery charger to the center terminal wires of the regulator with the regulator removed and the 30 amp fuse did not blow.  Waiting for a replacement regulator.

 

Just for the asking, the output of the regulator has two Black wires.  One goes to the 30 amp fuse and then to the battery side of the starter relay.  Any idea where the other wire goes.  According to all the schematics provided by a forum member, all other loads come directly from the battery through a fuse.  On the schematics of the alternator portion, the output of the regulator is connected to the30 Amp fuse and from there it either goes to the battery or to pin 9 of the Engine connector. All of the other circuits go through another fuse (20 Amp) and then to the ignition switch.  Working in a 25 degree garage limits how much wire tracing I want to tackle.  If need be I guess I'll start pulling on wires to trace the termination of each.

 

Could this year have a different wiring configuration.

The information I have the engine is P220G-I-10540B  ID 3120OE01.

 

WHX21, thank you for your indulgence as I work my way through this problem.  At least the electric fuel pump is working fine!

 

Regards,

Dan K.

 

Share this post


Link to post
Share on other sites
 
WHX??

No problem Dan. Your wiring is a bit different than any of the three  520s I have. Mine are exactly like the wiring diagram I posted. Does yours look like it been majorly worked on before? Sounds like the B+ from the reg is landed on the heavy cable battery at the starter solenoid which is fine but ther should only be one wire on the center post of the reg. Yes find out where the other black wire goes.

Share this post


Link to post
Share on other sites
 
jimr

Todays task is to separate the wires at the regulator and trace the second wire.  Since this second wire goes into a "factory" harness, I think it is originals.  Tracing will confirm.  Just waiting for the kero heater to warm up the garage.

 

Dan K.

Share this post


Link to post
Share on other sites
 
jimr

Using my telephone tracing tool I got close to the engine connector.  I separated this connector and the checked with my ohmmeter for continuity.  Traced to the Gray wire of the connector and using the schematic traced to the Tach.  don't know the operation of the tach with battery voltage on two terminals of the tach but the indication when the engine was running of a very erratic RPM indication.  I measured the resistance to ground on the Batt terminal wire of the regulator and with the key ON I got 11.6 ohms, this would indicate about 1 amp draw.  without battery charging, that should be fine.  Just waiting for the USPS to deliver the new regulator.

 

Dan K.

Share this post


Link to post
Share on other sites
 
jimr

Well the new regulator came on Saturday but I was not up to spending time in the cold so I worked on it on Sunday.  Again checked all the connections, installed the new regulator and 30 amp fuse.  Started the tractor and immediately the fuse blew.  Checked the output of the regulator and it was -2.3 volts.  At this point I had spent to much time on it and called the owner.  He relayed this problem has been around for many years.  My suggestion was to purchase an external charger and after each use charge the battery.

 

I suspect the 36 volt output of the alternator is either faulty or the regulators being produced in Taiwan are for other engines and they just included this model.  I have one other test I am going to try when the temperatures again are in the 60-70 range.  If my suspicion is correct, in that the stator voltage is to high, I'll build a regulator that will withstand this voltage and provide about 14 volts out for charging the battery.  I have built many regulators for other systems so this should not be anything difficult.

 

Thanks for all the help.

 

Dan K

Share this post


Link to post
Share on other sites
 
gwest_ca

I believe the original regulators had 4 terminals with the grey tach wire going to one of the AC terminals and if I remember correctly it makes as difference as to which AC terminal.

Try removing the wire that goes from the regulator to the tach and see if you loose the short.

 

Garry

Share this post


Link to post
Share on other sites
 
jimr

I would have a better understanding of the operation of the tach if the connection was to the AC portion of the regulator.  The tach would count the frequency of the AC and convert it to RPM.  Connecting to the DC output seems incorrect.  That still would not explain the blowing of the 30 AMP fuse at the battery connection.  I am sure I checked continuity from the DC out of the regulator directly to the 30 AMP fuse.

Since I have returned the tractor to the owner I don't have it available to do more troubleshooting.  Also I think the next time a regulator is needed I'll have the owner do the purchasing.  He may opt to get an OEM unit rather than one made in Taiwan.  It may be the Taiwanese units are physically the same but internally they do not match the OEM.

I have written a procedure to follow after separating the tach lead from the DC out.  There are a number of steps I can segregate the circuit to determine the root cause.  I plan on using an external charger in place of the regulator to simulate the regulator output but that is at another time.

 

To start the T/S again I'd like to know if someone knows the design/correct output of the stator.  To me 36 volts on each side of the regulator seems very high.  I do have a Cub Cadet that I can check the stator output but it is Winterized at this time and I don't want to go through the process again.

 

Until the temps get higher, thanks to all for the inspiration and have a Merry Christmas and Happy New Year.

Regards,

Dan K.

Share this post


Link to post
Share on other sites
 
gwest_ca

The P220 service manual. Click on the picture and the engines/tractors are listed

The Onan's Wheel Horse used have a 20 amp stator. The A, B, C and D are part of the engine spec number.

 

Garry

 

 

492-4006 Onan P216 P218 P220 P224 SM Alt test output SS.jpg

Share this post


Link to post
Share on other sites
 
jimr

I have some confusion.  This tractor  is a P220 and the above instructions say there should be an open from each AC lead to ground.  The schematic also shows only two wires.  A later diagram for the P220 shows three wires on the Stator and one going to ground with an internal resistance in the 1.0 to 1.5 ohm range.

I will take the AC output voltage in the range of 30 -40 volts as normal for any model.

Still have to do more T/S to find the problem.

 

As the diagram stated:

"These  typical  wiring  diagrams  show  the  basic  wiring  necessary for operation  of  the  engine.  Your  engine  may differ  in  circuitry  and  features  depending  on  how  the  equipment  manufacturer  chose  to  configure  the  final product"

 

so having a grounded stator may be correct.

 

Thanks for the information.

 

Regards,

Dan K

Share this post


Link to post
Share on other sites
 
jimr

Still thinking about the problem of blowing regulators and 30 Amp fuses and I looked at the wiring diagrams of other years.  The tractor I am working on is a 1988 model, the wiring of the 1990 model shows the Tach wire going to one of the AC posts on the regulator.  This seems much more consistent with how I think the tach should work.  The configuration as I received was with the Tach wire (Gray) connected to the B+ output of the regulator.

Also some of the individual circuit diagrams show the Stator not connected to ground where others show a ground connection.

Does anyone know which is correct?  If there is supposed to be NO connection to ground of the Stator, then this tractor may have a short on the Stator.  If it is supposed to be grounded, what should the resistance be between each leg to ground and between the legs with the regulator removed? 

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...