TN70 Trans Light & Error Code 81 - Help RickB :-)

[Jason_H]

Hopped in the tractor, fired her up and the transmission light was lit. Tractor wouldn't move. The indicators go off when you turn the key to 'ON' but as soon as the engine fires up, the tranny light comes on and stays on for about 30 or 40 seconds. Then it will go off and everything seems fine except for a new 81 code... Any tips? I was trying to wait until my next scheduled service to get my Error Code 47 fixed. This on is new and out of the blue. To be honest I normally start the tractor and jump down to fill the bucket with feed. So this could have been going on for some time.

Thanks in advance for the assistance.

 

[RickB]

Fault 81 transmission pressure switch shorted to ground or open. Hopefully caused by a failed pressure switch (not uncommon for a similar-aged group of tractors). Replace the sender, or test by jumpering the two wires going to the sender. Sender is located in transmission control valve on LH side of tractor just ahead of the LR axle and inboard of the fuel tank. Sender is 22MM hex and has two individual wires attached with flat spade connectors. Do not confuse with solenoid coils or the temperature sender which have weatherproof harness connectors. A short wire with two male spade connectors can be plugged into the two female spades in the chassis harness while you are waiting for the new pressure switch. If it moves, you have no real pressure problem. If you still get the fault with the jumper wire, there is a harness problem. Work from under the tractor, or pull the LR wheel, which I did with the first one, then worked from below on subsequent switch failures.

 

[Jason_H]

As usual, you're the MAN!! I still haven't ordered my manuals yet, I'm short on $$$. The tractor will shut the light off after about 30 or 40 seconds and everything works as it should. If she runs, should I keep working her? I shudder at the thought of moving round bales by hand/trailer/chain.

With the weather and fires down here hay is going for over $85.00 a bale, if you can find any. I've been supplementing with cubes and protein tubs but its crazy expensive! I'll call the dealer tomorrow and find out how much for a new part. I hope its cheap!!

I do honestly appreciate the help!

 

[RickB]

If it moves, its OK to use it. But I would jumper the switch to 1) prove it is the problem, and 2) prevent the switch from completely failing and disabling the tractor at an inopportune time/place.