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motox25

520-H Wiring Issues

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motox25

I've been digging into the 1991 520-H I purchased and have been restoring and ran into some electrical issues.  First, the tractor starts and runs but none of the electrical gauges work and neither does the light panel.  Upon digging deeper I found almost every safety switch has been bypassed and the tan wire off my ignition switch has been rerouted directly into the 9pin connector.  The PO only left 1 of the fuses in the box and the other has been jumped by a piece of wiring, the 3rd fuse is missing altogether.  Lastly, the 9 pin connector is melted and looks like it overheated.  I've heard this can be caused by a dirty and corroded connection, what would prevent this from happening?  Also, what do you guys recommend I do as far as replacing the 9 pin connector, should I simply replace it with another one or is there a better solution?

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cdsl810

I made sure that the connections were all intact on the 9-pin, cleaned with contact cleaner and hit each connection with dielectric grease, then snapped it back together. No more problems with that thing... But, I was having constant problems with two of the fuses coming loose in the fuse block so I removed the thing and replaced it with three individual weatherproof heavy duty fuse holders. No more electrical issues.

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boovuc

I would recommend as above. Most other 300 series tractors use the individual fuse holders rather than the fuse block on the 520 which collects dirt and moisture at the contacts. I had to replace my fuse holder on the 520 for the 3 amp circuit to bring back my dash components. The 9 pin connector, as long as it is intact should be cleaned, sprayed with a contact cleaner and then coated with dielectric grease. if there are broken pins or the plastic is coming apart, it requires replacing. The biggest thing is to get those fuses back into operation. Jumped fuses are not cool! As far as safety switches..............only one of my tractors has fully functional safety switches. They are a requirement if the kids run them. Other than that, IMHO, the seat switch is the only real switch I think should be hooked up.

Edited by boovuc

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cdsl810

A word of caution regarding the fuse block : two connectors are bridged on one side, take care to join the same wires if you replace the fuse block. At least, this is the case on my 1990 520-H.

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motox25

My wiring connector will definitely have to be replaced, I'm guessing I can pick up a 9 pin aftermarket connector. As far as the existing wiring goes I think I can just clip it at the connector and recrimp the wires. I will definitely use dielectric grease so this doesn't happen again.

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motox25

I got the 520 started today, without doing any work to the wiring except hitting all the connectors with contact cleaner.  I purchased a new 9 pin connector and some dielectric grease to seal the connector.  I do have a question I'm hoping someone can answer, like I said earlier there is a tan wire coming off the ignition switch which has been patched into the 9-pin connector with the blue wire going to the starter.  I'm guessing this has been done to bypass all the safety switches?  I have discovered my indicator lights actually are lighting up when the key is turned but none of the gauges are working.  I see a cut tan wire going into the indicator light board, I'm assuming this is where I need to reattach the tan wire?  Wanted to make sure before I burned something up  :) The PTO wiring has been cut out, I'm assuming this will prevent the engine from starting once I reattach this tan wire?  I'm going to try to salvage my fuse block by cleaning all the contacts and replacing the fuses, but will be buying a new block if that doesn't work.

 

 

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gwest_ca

Detailed wiring diagrams

 

Garry

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ARK

A few words on dielectric grease!  At 12 VDC almost all grease is dielectric, meaning a non conductor.  Because dielectric greases are non conductors it is wrong to use it on any connection before that connection is made.

 

Typical use is to break the junction or connector, use a good quality contact cleaner then install the connector and break the connection at least 3x, look at the mating surface be sure dirt, oxides etc. are removed blow out with oil free compressed air then make the connection and then as a last rersort spread dielectric grease over the connection.  Wipe away excess.

 

Any older machine, car, motorcycle, tractor must like new machines be able to transmit current and DC current just by its nature is difficult when dielectric grease inhibits conduction.

 

Since we own older machines just do regular maintenance, keep connection tight and clean and expect to verify 12VDC electrics every 3 years.  Dielectric grease if used incorrectly cause more work than if they are not used.  Another way is to use heat shrink with dielectric placed in the shrink.  That way the joint must be made tight and clean before heat is applied to shrink the tube with dielectric.

 

You can get conductive greases that are used to aide conduction at Electric Wholesalers, they are used with dissimilar metals and plating industry

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Cable

Glenn Peditt makes a cover for the 520H 4 position fuse block.  The cover keeps dirt and water out of the block.  I think he was charging about $10 for one at last years tractor show. Replacement contracts are available for the fuse block.  The two position contact pair is a problem as they are not easy to find.  Try Terminal Supply Co or jumper two standard ones together.

 

As for the use of dielectric grease I agree it is not a good idea for the reasons already expressed here by others but also for an additional reason.  Close examination of the female pin reveals that it is split. With grease in the female contract it sometimes expands and splits when the male is inserted.  The grease has to go somewhere so something has to give.

 

There are two contracts on the 9-pin that are generally a problem, one comes from the voltage regulator and the other is the 12 VDC source that comes up from the battery connection at the starter. I recommend that these two be replaced with gold plated male and female contacts. Unless you have the correct crimping tool and are good at using it, soldering the pin-to-wire connection may be a good idea.

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Save Old Iron

The tan wire from the ignition switch goes to 2 different locations.

 

The S terminal will be powered by 12 volts when the ignition switch is in the START position.

 

Power will be applied to the SWITCHING RELAY and also terminal 8 of the indicator module. It appears the 12 volt power then proceeds out of pin 9 of the indicator module to the safety switches on the seat and the PTO.

 

Essentially the logic is the PTO switch, the seat switch and the SWITCHING RELAY all must have closed contacts to allow the 12 volts to power the START RELAY and therefore spin the starter motor.

 

Trace out the TAN wiring to the indicator pod and the SWITCHING RELAY. If both these wires are correctly attached, then we can proceed to troubleshoot the no start crank issue on the tractor.

 

 

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motox25

Thanks for your help, glad you said that I was honestly planning on packing my new 9 pin connector with dielectric grease. Hopefully after replacing the 9 pin connector and reconnecting the tan wire my gauges will start working again.

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