John Deere 7700 wiring diagram wanted

[3cpowertrain]

Hi has anyone got a wiring Diagram for a John Deere 7700 Tractor. Happy to pay.!! Any help appreciated

 

[NZ Tech]

Whats it doing?? Fault wise?

 

[3cpowertrain]

Morning. Keeps blowing the accessories relay fuse. And low voltage to the draft link sensor switch. She has had some previous repairs and modifications to some areas of the wiring over the years from what I can see.!!

 

[Tractortech]

Now Then..
What are you calling the draft sensor switch?? Is it the potentiometer for adjusting the draft sensitivity?? I think that will receive 5 volts from the hitch controller..

 

[3cpowertrain]

Morning the draft sensor.. that’s correct 5 volt feed out of the HCU. However we only have 1.7 volts. With the sensor connected and disconnected. Input voltage to HCU seem good.!! But would like to check the system through properly with a wiring diagram. Thanks

 

[Phil P]

Morning the draft sensor.. that’s correct 5 volt feed out of the HCU. However we only have 1.7 volts. With the sensor connected and disconnected. Input voltage to HCU seem good.!! But would like to check the system through properly with a wiring diagram. Thanks

Check the wires down to the draft sensor, if I remember right they run just behind one of the lift rams and can get crushed by dirt or small stones that get lodged behind the ram.

 

[3cpowertrain]

Hi thanks yes they are all ok. We have low voltage directly out of the HCU wire to the sensor

 

[Phil P]

Hi thanks yes they are all ok. We have low voltage directly out of the HCU wire to the sensor

I can’t remember what else the 5v supply powers, I think it goes to the hitch position as well as the depth control etc. If there’s a wire earthing on any of these systems you’ll get a voltage drop at the HCU.
It’s best to unplug from the HCU and check the wire to see if it’s shorted to ground if your supply to the hcu is good you may have to unplug all the sensors/switches first.
And don’t rule out a faulty HCU.

 

[3cpowertrain]

Hi thanks for your response. I have unplugged everything that I’m aware is on the 5 volt circuit but still that same. The HVU has been changed in its life as it’s got 7600 written on it but this was many years ago thanks again

 

[Tractortech]

Have you looked in the HCU for error codes??
Diagnostic fuse in F10, HCU address 01 type of thing??

 

[3cpowertrain]

Hi yes error code for low voltage on draft sensor.!!

 

[Tractortech]

Code 052??

 

[3cpowertrain]

Hi yes that’s the boy..!!

 

[Tractortech]

Morning the draft sensor.. that’s correct 5 volt feed out of the HCU. However we only have 1.7 volts. With the sensor connected and disconnected. Input voltage to HCU seem good.!! But would like to check the system through properly with a wiring diagram. Thanks

So, you have 1.7 volts at wire 883 as it leaves the HCU??

 

[3cpowertrain]

Morning yes that’s correct

 

[NZ Tech]

Morning. Keeps blowing the accessories relay fuse. And low voltage to the draft link sensor switch. She has had some previous repairs and modifications to some areas of the wiring over the years from what I can see.!!

Whats the fuse number. F ???

 

[3cpowertrain]

Morning not sure it’s the fuse marked HCU from memory. This is why I’m after a wiring diagram

 

[Tractortech]

It should be fuse F05. Is there a good 12v supply at the fuse??

 

[3cpowertrain]

Hi thanks for the message only just had a look at it again today after several months.. got a low voltage on wire 133 Orange.. also same wire bunker on a relay wire. Do you know where that feed comes from..
I put a separate feed into the 133 wire on the hcu but still love voltage on the draft sensor wire. And the other circuits have a 4.98 volts so still suspecting a hcu fault.

 

[Tractortech]

Wire 133 (orange) travels from terminal 85 of the LH turn relay K6, to terminal No S3 of the CCU. Wire 102 (red) supplies K6 with 12v, the CCU provides ground via 133 in an intermittent style for the LH indicator circuit.
Wire 133 isn't connected to the HCU at all..