TN70 will not move. No error codes

[ChuckFinch]

Somebody help me. I have a Tn70 and it will not move. It has the ELE shuttle shift. There is no trbl codes. The transmission light doesn't come on when it is started. It use to come on if you put it in gear to qiuck. You would then have to center the shuttle and it would move. The sensor that is on the left top of tranny was changed about 5 hours ago for the code of open or grounded sensor. Any ideas on what i need to check out?

 

[RickB]

You don't say which sensor or switch was changed, but I would change the transmission pressure switch given your (lack of) symptoms.

 

[ChuckFinch]

That was the sensor that was changed. I guess it could have went bad. I had to remove the rear tire go between the fuel tank and platform to access it before. Last time it gave me a error code. Is there a way to check to see if it went bad?

 

[ChuckFinch]

I have checked the sensor and it reads with a omh meter where the old one dosn't (transmission pressure sensor). I put a jumper wire across the leads and nothing moved. I tried to check the reverser on the dash. If it is in foward or reverse it will not start. Move it to neutral and it starts. That makes me think that it is working. Any ideas of what is next to check?

 

[howierd3866]

not saying it right but on a ts110 there a switch behind the clutch petal that when bad tractor wont move.. I do know the tn70 and ts110 our diff but its one more place to check until Rick gets back to you..And please post what fix it for us on here to know when we have the same problems..thanks and good luck

 

[Jbrink64]

I have checked the sensor and it reads with a omh meter where the old one dosn't (transmission pressure sensor). I put a jumper wire across the leads and nothing moved. I tried to check the reverser on the dash. If it is in foward or reverse it will not start. Move it to neutral and it starts. That makes me think that it is working. Any ideas of what is next to check?

Watch out for that one...

When you turn on the key switch, the ecu needs to see an open in the pressure switch circuit. Within, I think, 15 seconds after startup, the switch needs to close. If you jumper the switch before startup to "fool the ecu" , it gets you back by defaulting to a no go status.

You should have a NH person with an EST check it out, IMO.

 

[ChuckFinch]

Thanks guys. I will go back out and look for the clutch switch. Thanks for the heads up on how the ecu reads the switch. If it see's the switch closed before starting will it turn on the transmission disable light. The light is not coming on. This is killing me by not being able to figure this out. It may end up going to the shop if I don't figure this out in the next week.

 

[RickB]

I agree with Jbrink64. You need to have a tech with the diagnostic tool or EST-equipped laptop run a full diagnostic routine including a switch test and voltage test.

Enough of those pressure switches have failed that it is an easy go-to first attempt that is often the right guess. Beyond that, it is not good to continue swapping parts without troubleshooting. It may very well be that your ECU (computer) has failed.

 

[ChuckFinch]

The ECU has been replaced once already years ago. I guess it's a trip to the shop.

 

[Jbrink64]

A couple of thoughts. The trans malfunction light doesn't come on. Is the bulb OK?

With the light not coming on, and the trans disabled, is the ECU powering up? Check all fuses, loose/dirty connector at the ECU? Non cab units can get water under the dash cowling in severe weather.