After Trans oil Change/harsh downshift now

[Rockit]

On my 2002 4.4 with 125k I had the trans oil changed and filter changed.

OEM fluid and filter. The old fluid was black.

I now have harsh downshift...also if I tap the gas it slightly bangs....none of this is extreme but now its there and it wasn't before the oil change.

I was wondering if anyone else had this problem. Any ideas maybe add something to the oil?

Thanks

[bhennrich]

Originally Posted by Rockit

On my 2002 4.4 with 125k I had the trans oil changed and filter changed.

OEM fluid and filter. The old fluid was black.

I now have harsh downshift...also if I tap the gas it slightly bangs....none of this is extreme but now its there and it wasn't before the oil change.

I was wondering if anyone else had this problem. Any ideas maybe add something to the oil?

Thanks

How much fluid came out and how much was put back in? How did they change it? If you did a power flush it is very possible that the trans is shocked and that is not good. You want to keep fluid change in a trans to under 50% if possible.

[Rockit]

Originally Posted by bhennrich

How much fluid came out and how much was put back in? How did they change it? If you did a power flush it is very possible that the trans is shocked and that is not good. You want to keep fluid change in a trans to under 50% if possible.

They put as much in as came out. They dropped the pan, changed the filter. No flush, not sure if the torque converter drains or not.

I could not believe how dirty the fluid was. It was black.

[aureliusmax]

you need to do a transmission pressure re-learn to the computer. i haven't done it before but that's what I read from other threads here.

[Rockit]

Originally Posted by aureliusmax

you need to do a transmission pressure re-learn to the computer. i haven't done it before but that's what I read from other threads here.

Thanks, I'll see what I can fin out.

[Overboost]

This is always my fear when considering a transmission fluid/filter change. Some have no issues and some have issues after the change. From reading and researching, I can not get a clear understanding on the adaptation resets for a simple oil and filter change.

I would love to hear more theories on what should actually be done when changing the oil/filter in both ZF and GM automatic gearboxes and also the recurring conversations of leaving high mileage transmission alone vs. diving in and rolling the dice.

One guy I would love to hear from the is automatic gearbox guru over in the UK (I always forget his name) but he knows his stuff. (RRPhil)?

[andrewwynn]

Clean the transmission TCM and gear selector switch cables.

A dirty pin (and there are about 25), will give you the exact symptoms. I had this problem twice.

[Rockit]

Originally Posted by andrewwynn

Clean the transmission TCM and gear selector switch cables.

A dirty pin (and there are about 25), will give you the exact symptoms. I had this problem twice.

Can you get a little more detailed please. The TCM is the same as the neutral safety switch? Does it unbolt or how to you clean it?

[andrewwynn]

Originally Posted by Rockit

Can you get a little more detailed please. The TCM is the same as the neutral safety switch? Does it unbolt or how to you clean it?

TCM is transmission control module in the e-box with the DME.

You are calling the transmission position switch the metal safety switch. It actually reports every gear not just park and neutral. I’ve been referring to it as the selector switch not sure where I heard that but I just looked it up on real oem. BMW calls it the transmission position switch.

Anyhow less than a week ago somebody on xo couldn’t start their x5 because the connector to their position switch was loose (the locking collar didn’t lock).

Since the TCM needs feedback of which gear is selected to determine how to control the transmission, all hell breaks loose when it reports strangeness like it’s in gear 54 which mind did once.



Note there is a connector after about 8” of wire that’s the position switch connector I don’t know if that goes directly toward the TCM or plugs into the transmission and piggy backs into the main transmission connector.

I have the 3.0 and it uses an internal position switch so I only have one connector.

[upallnight]

He has the ZF trans not the GM trans. Two completely different trans. Usually slamming into gears can be associated with pressure from the valve body. Could be time for a valve body rebuild. Google valve body for the ZF trans and sticking valve.