# John Deere 8630 tripping breakers



## kchallener (11 mo ago)

I have a John Deere 8630 completely rebuilt. New wiring harnesses, new breakers, relays, cables, most of the cab is new as well. The breakers on both the hot side and switched side of the power supply all trip. If I manually trip them (12V power supply) everything works. What am I missing here?


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## sixbales (May 18, 2011)

What am I missing here? Are you are saying that all of the breakers trip, but if you manually reset them, everything works?


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## kchallener (11 mo ago)

I can reset them and get the tractor to start, turn on lights, fans, etc. As soon as I remove power they trip back. I have tried removing all circuits, then adding them back one at a time. The only thing new is that the lights are all LEDs, but even if I remove all the light circuits the main breaker from the starter relay trips.


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## sixbales (May 18, 2011)

You are saying that all of the breakers trip when you turn the power "off" with the keyswitch? You must be introducing a power surge when you turn the key to "off"? Maybe an inductive kick?


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## BinVa (Sep 21, 2020)

Have you replaced the ignition switch or wiring to it? Sounds like you’re getting a short at the bussbar…are you sure the charging circuit harness is wired correctly to the relay?


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## BigT (Sep 15, 2014)

The keyswitch may be shorting all circuits momentarily as you switch it off.


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## kchallener (11 mo ago)

BigT said:


> The keyswitch may be shorting all circuits momentarily as you switch it off.


I ordered a new key switch. The wiring harness is new. Charging circuit seems quite straight forward. Starter relay is new, as is the accessory relay. I let you know on the key switch.


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## BinVa (Sep 21, 2020)

Kc....
If I may ask...what brought on the wire harness change out? Was this preventive for dry/cracked shielding? Have you had good luck with the tractor in general? Some of the 30 series tractors were problematic tho I had good luck with a 4430, the 8630 had its share of issues. B.


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## BigT (Sep 15, 2014)

Question: Do all the breakers trip when you turn the keyswitch "on" and also when you turn the keyswitch "off"??


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## kchallener (11 mo ago)

BigT said:


> Question: Do all the breakers trip when you turn the keyswitch "on" and also when you turn the keyswitch "off"??


yes, they all trip, but will not reset without apply a 12 volt charge accross


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## Tx Jim (Jul 28, 2020)

I thought circuit breakers of that era that JD utilized tripped due to heat created then reset when they cooled off.


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## kchallener (11 mo ago)

Tx Jim said:


> I thought circuit breakers of that era that JD utilized tripped due to heat created then reset when they cooled off.


OK, so I changed the ignition switch (swapped out with a 4030 I have with a new switch). No change. I thought there must be a very large (direct) short to explain the problem. The solution: There is an inline fuse in the line from the circuit breaker bar to the starter selenoid. That fuse was fine, but the internal contacts were badly corroded (its on the front side of the firewall and presumably can get water inside). I could not locate a replacement from Deere, so I put an inline fuse with 8 guage wire in place (80 amp). So far, no problems. Should probably have noted that fuse holder was bad in the first place, rather than just checking the fuse....Inadequate (or intermittantly none) volate to the circuit breakers.

Ken


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