Thread: D3 - is a transmission firmware update risky?

Originally Posted by goofyr

I’m hoping that the update will remove an annoying habit for the transmission to hold a lower gear when going up a hill near where I live when cold. Gap mentioned the update for mine if for better low speed behaviour. I’m also a bit OCD with updating software

When I changed the fluid and rebuilt the valve body in the ZF6HP28 I hard reset the car, then drove it gently at first for the TCM to relearn the shift points (I put new solenoids in, they maintain a certain opening voltage that the TCM learns, so new solenoids resets the base values as per firmware coding.

I had No need to reset adaption etc.

Re holding gear when cold, I understand this is a valve body/torque converter behaviour issue as in it won't let the transmission shift into a higher gear if the line pressure for a particular gear is not right. This protects the t.c and valve body plus clutch packs. I notice this here in Perth on colder mornings, not at all in summer. The car will hold 5th gear until the TCM has determined all is good, then smoothly shifts into 6th. This only happens on cold starts and only once when shifting through the gears. , everything else is normal. I can overide it by using sport mode and selecting 6th gear manually....

I guess with the firmware update, perhaps the pressure setpoints at which the TCM tells the solenoids open/close could be slighly adjusted to give a smoother shifting experience between gears.

Originally Posted by loanrangie

On the docs that came with my genuine solenoids it stated to not reset adaptions unless you are replacing hardware in the trans.

Can you post copies on this thread? That's important information