Reversed jumper cable now tractor won't start

[curlesw]

My battery was failing and was planning to get a new one. I needed to use the tractor (B7800) so decided to jump the battery; it was late and I was in a hurry and swapped the pos/neg cables.,,dang it!

I corrected it but damage was already done. I checked the fuses in the box, all good. The 30amp at the starter was blown so I changed it. I also replaced the battery. But, the tractor still does not crank.

When I turn the key, the glow plug and oil pressure lights come on (see pic), but the electrical light (middle one) does not. The blinkers and dashboard lights operate as well.

Any idea where to look next? thanks!

v/r
Wayne C.

 

[North Idaho Wolfman]

Double check that you don't have the PTO engaged or any other feature that will stop it from cranking.

Then I would start with ther WSM and the wiring scematic and figure out the most likely cause of what you could have burnt up.

 

[curlesw]

Thanks for the reminder on the PTO, I checked and everything seems to be in the proper position.

I am working through the electrical system now. What is WSM?

v/r
Wayne C.

 

[200mph]

WSM = Work Ship Manual

 

[Dave_eng]

Do you have an Owners' manual with a wiring diagram which you could post?

Dave

 

[D2Cat]

I think there is a fusable link just before the starter. Might check there.

 

[curlesw]

I have been working through the electrical system: all switch are good, starter works, fuses ok (including the 30A at the starter).

I have not been able to locate the two diodes on the mid/read PTO circuits. Does anyone know where these are located so I can check them?

v/r
Wayne C.

 

[Dave_eng]

I have been working through the electrical system: all switch are good, starter works, fuses ok (including the 30A at the starter).

I have not been able to locate the two diodes on the mid/read PTO circuits. Does anyone know where these are located so I can check them?

v/r
Wayne C.

Does your wiring diagram show diodes..... not common on Kubota's but John Deere is a big user of them.

Messicks does not turn up any for your tractor.

Dave

 

[curlesw]

Does your wiring diagram show diodes..... not common on Kubota's but John Deere is a big user of them.

Messicks does not turn up any for your tractor.

Dave

Yes, per the electrical schematic, the diodes are part of the mid/rear PTO circuits as well as the seat/seat reverse circuit. Maybe the diodes are built into the mid/rear PTO switch...will check that.


v/r
Wayne C.

 

[curlesw]

Just checked Messick's, the mid/rear switches are the same part # but the clutch switch is different, seems odd. Also, does not show the HST switch but looks similar to the clutch switch.

The mystery continues....

v/r
Wayne C.

 

[Dave_eng]

Just checked Messick's, the mid/rear switches are the same part # but the clutch switch is different, seems odd. Also, does not show the HST switch but looks similar to the clutch switch.

The mystery continues....

v/r
Wayne C.

A Diode for voltage spike protection will be associated with a relay or solenoid not a simple switch.

Some relays incorporate a diode within.

Dave

 

[curlesw]

I hear you; I checked the only relay on the schematic and it's part of the key stop circuit and working.

Here's the diode in the electrical schematic. I have visually identified and checked ever component on the schematic except these diodes, grrrrrrr. ANy other ideas? Appreciate the feedback.

Will run up to the service dept and have them check the details parts diagram as that should show the actual location.


v/r
Wayne C.

 

[Tughill Tom]

I think there is a fusable link just before the starter. Might check there.

DING,DING... we Have a winner!

 

[curlesw]

DING,DING... we Have a winner!

Done, first thing I replaced....thanks.

v/r
Wayne C.

 

[Dave_eng]

I hear you; I checked the only relay on the schematic and it's part of the key stop circuit and working.

Here's the diode in the electrical schematic. I have visually identified and checked ever component on the schematic except these diodes, grrrrrrr. ANy other ideas? Appreciate the feedback.

Will run up to the service dept and have them check the details parts diagram as that should show the actual location.


v/r
Wayne C.

Your image is too small to read.

I have seen diodes used to prevent one circuit from back feeding another.

Like fusible links, diodes are likely to be a plug in style but not readily apparent.

Photos attached of another brand's diode style

Dave

 

[curlesw]

Do you have an Owners' manual with a wiring diagram which you could post?

Dave

Here they are, thanks!

v/r
Wayne C.

 

[curlesw]

Your image is too small to read.

I have seen diodes used to prevent one circuit from back feeding another.

Like fusible links, diodes are likely to be a plug in style but not readily apparent.

Photos attached of another brand's diode style

Dave

Thanks, will start my search again...these are images are helpful. Hopefully my fresh eyes will find them...if not, back up to the service dept for help.

I uploaded the wiring diagram as well.

v/r
Wayne C.