AHS 1,439 #1 Posted March 5 Ok! 520H, i cant figure out what year year it is cause the tag is covered up by the steel for the cab. So, the battery’s charged but nobody home when I turn the key to ‘on’, no lights on the gauges… nothing. When you turn it to start… no start. Keyswitch? That’s the first thing i would think of, right? 2 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,031 #2 Posted March 5 Going by the maroon hood decal you have a 1988 or 1989 model which use the same wiring diagram. 2 1 Share this post Link to post Share on other sites
squonk 41,018 #3 Posted March 5 Check the 9 pin engine connector by the fuse block. The pins like to corrode and melt. 4 Share this post Link to post Share on other sites
Ed Kennell 38,021 #4 Posted March 5 (edited) Yes, '88 or '89. 1990 went to the motion lever on the steering wheel. Safety switches prevent start cycle. Check the seat, PTO, neutral on the motion lever switches. Edited March 5 by Ed Kennell 4 Share this post Link to post Share on other sites
AHS 1,439 #5 Posted March 5 6 hours ago, squonk said: Check the 9 pin engine connector by the fuse block. The pins like to corrode and melt. Ok! 1 Share this post Link to post Share on other sites
lynnmor 7,302 #6 Posted March 5 In addition to checking the 9 pin connector, your tractor has several fuses, be sure to check the 30 amp one going to the starter solenoid. 4 Share this post Link to post Share on other sites
953 nut 55,050 #7 Posted March 5 The fuses are near he battery and over time the acid fumes from charging the battery will corrode the fuse holders making a poor connection resulting in fuse failure. 1 1 Share this post Link to post Share on other sites
Ed Kennell 38,021 #8 Posted March 6 1 hour ago, lynnmor said: 30 amp one going to the starter solenoid. Yes, I have found this fuse not blown, but the legs corroded away. It is at the bottom front of the engine. 2 Share this post Link to post Share on other sites
AHS 1,439 #9 Posted March 6 10 hours ago, lynnmor said: In addition to checking the 9 pin connector, your tractor has several fuses, be sure to check the 30 amp one going to the starter solenoid. Ok, the 30A (by the starter solenoid), is the only one I have power to. starter solenoid to the 20A fuse to the B on the key switch, I don’t even have power there. I don’t even have power at the 9 pin connector…. It all points to the starter solenoid!! Let me figure out what’s going on!! Thank you! 2 Share this post Link to post Share on other sites
cleat 5,808 #10 Posted March 6 The 30A fuse by the starter solenoid is for the charge circuit and does not affect anything else. There is another wire that feeds from the start solenoid (just a connection point for battery power) that feeds up and through the 9 pin then to fuse 20 and on to the ignition switch. The wire colours change on the engine itself depending on year (wire diagram shows it as black) but the wire colour after the 9 pin up to the 20 A fuse and to the keyswitch is red. The connector at the keyswitch can get corroded and cause issues as well as the fuse holder and the 9 pin. Wheel horse 520H wire diagram.pdf 3 Share this post Link to post Share on other sites
kpinnc 11,895 #11 Posted March 6 (edited) 3 hours ago, AHS said: Let me figure out what’s going on!! Says everyone who ever owned a 520-H!!! Gotta love 'em, but sometimes not really... Times you want to plug all the guage holes and straight wire the dang thing! Edited March 6 by kpinnc 2 Share this post Link to post Share on other sites
AHS 1,439 #12 Posted March 6 6 hours ago, kpinnc said: Says everyone who ever owned a 520-H!!! Gotta love 'em, but sometimes not really... Times you want to plug all the guage holes and straight wire the dang thing! I know!!! The seat switch is pressed in and wont come out….just replace the seat seat switch… or make believe it didn’t exist! The 3 wire setup on the seat switch is interesting, of course one of them is just an indicator light. 2 Share this post Link to post Share on other sites
AHS 1,439 #13 Posted March 6 Ok, i messed with the 520 after work. I got 12V on the motor side of the 9 pin harness, (motor side, 12V black wire that connects thru the 9 pin connector to the red wire). In the picture there are two 15A fuses (it came that way, i swear!). Which one is supposed to be the 20A? The fuse next to the motor or the battery? I believe the 20A is next to the battery?? 1 Share this post Link to post Share on other sites
lynnmor 7,302 #14 Posted March 6 Download the Demystification Guide, your information starts on page 7-119. 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,031 #15 Posted March 7 Does your test switch for the idiot lights work? That circuit is connected to the 20 amp fuse and the 30 amp fuse at the engine. Remove 20 amp fuse and test no longer works? The other 10 amp fuse supplies the gauges but the 20 amp must be good before it will work. 1 Share this post Link to post Share on other sites
AHS 1,439 #16 Posted March 7 9 hours ago, gwest_ca said: Does your test switch for the idiot lights work? That circuit is connected to the 20 amp fuse and the 30 amp fuse at the engine. Remove 20 amp fuse and test no longer works? The other 10 amp fuse supplies the gauges but the 20 amp must be good before it will work. I have 2 15A circuits. I would like to know which one is the 20A, the fuse next to the battery or the fuse next to the engine. I have no idiot lights. 1 Share this post Link to post Share on other sites
AHS 1,439 #17 Posted March 7 How about this, maybe i was a bit confusing. Take a pic of your 88-89 520H, please. (like the one down below). 1 Share this post Link to post Share on other sites
Handy Don 12,131 #18 Posted March 7 2 hours ago, AHS said: How about this, maybe i was a bit confusing. Take a pic of your 88-89 520H, please. (like the one down below). There is no extra risk if the tractor runs well with two 15’s. Worst case is a blown fuse and then I’d replace the blown one with the 20. 1 Share this post Link to post Share on other sites
cleat 5,808 #19 Posted March 7 (edited) I took pictures of my 520H and my 520HC. The 520H has a 10 and a 20 fuse with the 20A close to the engine and it has power at all times irregardless of ignition switch being on or off. The 10A fuse has power with the ignition switch on. The 520HC has a 10 and a 15 fuse with the 15A away from the engine and it has power at all times irregardless of ignition switch being on or off. The 10A fuse has power with the ignition switch on. What this tells me is that fuse position is irrelevent as the fuse holder can get clipped on in any way. Biggest thing is to check for power and also wire colour as the constant power fuse will have red wires and the switched fuse will have pink and/or green wires. Edited March 7 by cleat 3 Share this post Link to post Share on other sites
Ed Kennell 38,021 #20 Posted March 7 (edited) Here's my '88 520H fuses. 20A to the rear and 15A to the front. Being 36 years old, no guarantee they are as designed from the factory. But the tractor runs fine with no starting or charging issues. Edited March 7 by Ed Kennell 2 Share this post Link to post Share on other sites
kpinnc 11,895 #21 Posted March 7 2 hours ago, cleat said: Biggest thing is to check for power and also wire colour as the constant power fuse will have red wires and the switched fuse will have pink and/or green wires. You mean there are rules to all those colors? 2 Share this post Link to post Share on other sites
AHS 1,439 #22 Posted March 7 Ya, I have no continuity between my red wire on the 9 pin connector and the fuse… @cleat i guess I’ll have to take the belt cover off the and find out which wire go to what! It’s a lil more complicated than the 77 B80 to work on wiring! Ha! 1 Share this post Link to post Share on other sites
cleat 5,808 #23 Posted March 7 3 hours ago, AHS said: Ya, I have no continuity between my red wire on the 9 pin connector and the fuse… @cleat i guess I’ll have to take the belt cover off the and find out which wire go to what! It’s a lil more complicated than the 77 B80 to work on wiring! Ha! Actually if you ignore all the guage wiring it is not too bad The early 520's like yours are simpler and easier to work on (that is why I convert all of mine to be that way) without the extra relays under the battery. Also you already have the charge wire directly to the start solenoid which takes a lot of load off of the 9 pin connector. It should not be too hard to trace that red wire through the harness. 2 Share this post Link to post Share on other sites
AHS 1,439 #24 Posted March 7 I found it!! I took the battery out and then i got to the spot in between the fuse and the 9 pin connector, where the break was. The gauges worked for a second then the fuse blew….but it started.. and ran like a champ. I noticed it wouldn’t idle down below 1000 -1300 rpms. I sprayed some throttle body spray at the rear part of the intake and it made a noise. The intakes gasket on the rear side is gone. I have so many questions about the Onan 20! Mine has 1500 hours on it and i wanna keep it running!! 3 Share this post Link to post Share on other sites
lynnmor 7,302 #25 Posted March 8 (edited) Idle speed is to be 1200 RPM and maximum throttle is 3600 RPM. To adjust carburetor and governor do this: Back off the idle speed screw, located near the throttle cable towards the front of the engine, about 2 turns. Adjust the idle stop screw, located on the rear side of the carburetor, to 1000 RPM. Adjust the idle mixture screw for the highest and best idle and readjust the stop screw as needed to maintain 1000 RPM. Repeat the last step as needed. Adjust the idle speed screw to 1200 RPM. The above procedure will give you a governed idle. Move throttle to full, the speed should be 3600 RPM, bend throttle stop if adjustment is needed. Use genuine Onan intake gaskets, some cheap imports turn to mush quickly. Edited March 8 by lynnmor 2 Share this post Link to post Share on other sites
