jmunzke

1989 520H Electrical issues

10 posts in this topic

ID: 1   Posted

Well all was running great until I took the compressor to blow some of the dust and grass away from the engine.  Engine won't start.  I can jump a wire from the + terminal to the solenoid, turn the key, and it will start.  Remove the jumper and it dies.  I haven't found any loose connections.  The 3 fuses are good.  The PTO is not engaged.  Battery is new and charged.  Something is failing between the key switch and the solenoid, where should I start?

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ID: 2   Posted

Garry

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ID: 3   Posted

This would be a great start, if I was more mechanically inclined. Is there any way to dumb it down.  The schematics are a bit, ......abstract. .......

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ID: 4   Posted

Sure sounds like a safety switch is not making, whether the PTO, brake pedal, motion control lever, or seat, I had a motion control switch that was actually "good" but the actuator arm had broken off so it was making the circuit needing a jumper wire to start with the key, only took me a month to find/figure it out, Jeff.

IMAG2067.jpg

IMAG2141.jpg

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ID: 5   Posted

This section of the huge Demystification Guide explains how the illustrations work starting on page 2-5.

 

Two circles joined by a line (o---o) indicate a switch or relay is closed meaning power can flow through it from contact to contact.

If two circles are not joined (o-/ o) the switch or relay is open so power can not flow from contact to contact.

 

There are two pto switches. One controls the ignition and the other controls the starter. You need to use the wire colors to identify which switch does what.

 

For the starter

The ignition switch needs to power the S terminal of the ignition switch

which powers the pto switch

which powers the neutral switch

which powers the relay coil that produces a magnet that draws the contacts in the relay closed

which powers the starter.

 

For the ignition

The ignition switch needs to power the I (eye) terminal of the ignition switch

which powers the pto switch

which powers the seat switch

which powers the ignition coil.

 

A common problem is the 8 or 9 pin connector that joins the tractor wiring harness to the engine wiring harness. The plastic connector is white so if one of the wire connectors has overheated it leaves discoloration at that point indicating a poor electrical connection.

 

From your description of the problem I can't tell if the starter circuit or the ignition circuit is your problem.

Also make sure the ignition switch is getting battery power on the B terminal.

A simple 12 volt test light is all you need.

 

Garry

 

 

 

 

 

 

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ID: 6   Posted

You may have blown some chaff into one of the safety switches or knocked a connection loose.

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ID: 7   Posted

Thanks for the great info. So far switches seem to be mechanically operable. 9 pin looks ok. I found this (see pictures) which looks like a chip or relay?  Has a burned white wire going into it. What is it?

IMG_5604.JPG

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ID: 8   Posted

It's the voltage regulator, you need to fix that.  Probably not the issue you are after, but still needs done.

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ID: 9   Posted

Eureka!  Thanks to all the advice here for the novice visual learner.  After checking all the switches, unplugging and re-plugging every electrical connection, and generally just trying to clean things up in there; I discovered the issue, or part of the issue.  The PO put an inline fuse holder for glass fuses.  The holder was not holding the connection tight enough to engage the fuse.  I changed it out for a flat fuse style.  Voila.  And I didn't change the regulator, but put a new blade where it looked like it had been shorting,  Will keep an eye on that.  Napa says those regulators are 85 bucks!  Does anyone have a more affordable solution should I need one?  

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2 hours ago, jmunzke said:

  And I didn't change the regulator, but put a new blade where it looked like it had been shorting,  Will keep an eye on that.  Napa says those regulators are 85 bucks!  Does anyone have a more affordable solution should I need one?  

Yes sir, eBay or Amazon $10-20 and yes I have an eBay version on one of mine and so far no complaints, Jeff.

IMAG2028.jpg

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