Case 521D randomly shifting transmission

[GMYard]

We have a Case 521D (S/N JEE0133064) Wheel Loader. We keep it in 2nd gear on the yard and use the downshift button on the joystick when going into piles. Recently it began randomly shifting gears (1-4 all gears) with no rhyme or reason, even upshifting when under a load. The automatic switch is not engaged, although engaging it seems to minimize the shifting but not correct it.

Does anyone have any ideas or suggestions?

Thanks.

 

[Bigbert]

Hi GMYard,
transmission is a ZF 4WG120 or 150?.
I'd assume there is some wiring issue at output speed sensor. Wires, plug or sensor itself.

 

[GMYard]

Thanks Bigbert.

I'm not sure on the model of the trans. I will check out the output speed sensor. I have contacted several Case service departments around and I get the same response from all of them, "I don't know, I've never had that problem before."

 

[uptight excavating]

I am closely watching this post. I have a similar but slightly different problem with a 521e. It sometimes starts in a different gear than selected. The dealer basically gave up after changing one of the four speed sensors on the trans. I don't remember which one was changed but after 2 service calls and $2000 dollars I decided to live with it.

 

[GMYard]

It may be a few days before I get to it. I will keep you posted.

 

[Coy Lancaster]

When is the last time(if ever) the trans was recalibrated? Have you checked error codes?

 

[uptight excavating]

In my case the transmission was recalibrated by the dealer on the first service call. No error codes are present.

 

[Coy Lancaster]

I would think that there may be a output speed sensor or the shift solenoid may be an issue. Try and put it back in total shift mode where it'll manually shift in all gears and see what it does.

 

[uptight excavating]

We normally run in the auto mode. But it doesn't matter what mode you run it in. It will not switch gears until it decides to on its own. We have tried all combinations and it is still the same. The dealer spoke to the factory and they had never heard of this and had no suggestions. I am thinking that we are on our own.

 

[Coy Lancaster]

There is a member on here named Big Bert he works at the ZF factory and is very knowledgeable about these transmissions. If you contact him be sure and have trans model and serial number. I've not heard of first and second doing what you describe either. You could have a blown gasket in the control valve. If you have a ohm meter you can test each speed sensor individually.

 

[Bigbert]

Thank you Coy for the compliments.
The D model, I assume, got the 4WG130 or 160 with EST 37 TCU box.
As the system doesn't throw any error codes I'd assume there is an issue on gear selctor signals. I'm not sure whether the DW3 switch running directly to TCU (with wires) or via CAN.
But a clear statement about tranny model would help.

 

[uptight excavating]

Hello again. I didn't mean to hijack or confuse anyone by joining into this conversation. I will carry on with my own posting as soon as I have a chance. We are rushed right now and we have other things that are more urgent. Thanks Bigbert for taking an interest and hopefully we can discuss this further in the future.