John deere 3650 rev counter

[John 1594]

Just remembered an issue we had with a 3050 years ago...it was an intermittent fault where pressing the brake pedals would sometimes cause the fuse to blow what supplied power to the rev counter. Swapped fuse board and cleaned all the multipin plugs, still kept doing it

eventually we found a single black wire with a blanked off end what led from the main dash loom, this had became trapped in amongst the brake pedal box, and when the pedal was pressed and then released, it was crushed and earthed against the pedal box

taped it up out of the way and it never played up again

 

[Johnny Deery]

Thanks Mursal. I am hoping that my problem isn't inside the gear cover. The engine was changed a few years back before I bought the tractor so that could be my problem.

I will check the wiring from the sensor first

 

[Johnny Deery]

Mursal, one thing i didn't mention is.... every now and then, the rev. counter needle gives a little kick and jumps around the place. Often happens when starting the tractor or when turning on the power key before starting
Thanks

 

[Mursal]

Not sure why that is ........

I think that sensor would be inductive rather than a hall switch, but could be wrong.
If inductive:
You can check the output from the sensor by, disconnecting the wiring and connect a multi-meter directly to the sensor. On AC voltage with the engine running you should get a small voltage, the voltage will change with revs.
If its a hall switch:
Connect multi-meter as before, but turn onto resistance or continuity. With the engine stopped crank the engine with a screwdriver, you should see the meter going to Zero (0) if the magnet lines up and closes the switch.

..........

 

[FG.]

Done a few 40 and 50 series with rev counter probs.
Most of the time it's cracked solder joints on circuit board.
Take right hand dash board out.
Dismantle all parts off carefully.
There's two 12 pin sockets and where the pins are soldered on to the circuit board, the solder fractures.
You have to look very close to see it, but if you heat/re-melt each blob of solder, problem will be sorted