Auto trans sand driving

Hi all.
Has anyone had this problem before?
Went down to Robe for some beach driving this weekend and towards the end of the day I noticed my car was sluggish from a standing start. After a little investigating realised the trans was stuck in third gear. Would not change down. This exact thing happened the last time I was down there.
The only fix we could come up with was to disconnect the battery for about ten minutes then once reconectted all was fine again. The first time it happened I was using the hold button on the trans to keep it in 2nd so I assumed there was a glitch with that so this time did not use it but still had the same problem.
Is it some sort of limp home mode or something like that?
I was in very soft sand and the trans was working very hard.
No warning lights or anything
Any thoughts?
Cheers

Yes, limp mode leaves it in 3rd because the A & B shift solenoids are deactivated. Should throw a fault code.
Probably got pretty hot but, if the trans temp light didn't come on, it didn't get to 140C which would have been bad for the box if you're not running synthetic fluid.

The TB45 trans cooler is pretty small, about half the size of the factory ZD30 cooler so it's a good idea to fit something better.
If it has a few kms already, might be smart to get it flushed with synthetic, get a bigger cooler and fit a trans temp gauge.

Ok. Is disconnecting the battery the only way to reset or will it reset after cooling down?

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Originally Posted by Chubba

Ok. Is disconnecting the battery the only way to reset or will it reset after cooling down?

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Check your codes to see what caused it. I don’t think overheating throws a code, it just lights up on the dash if it gets to 140C but you really want to avoid that.