5HP30 (540i Auto Trans) Question...

[MTechnik540i]

i'm very curious to find out what you learn... I have had a hard shift from second to third during moderate acceleration and warm tranny ever since I bought my car (2 years).

So far I have done:
- hard reset
- valve body replaced (Kirt)
- complete remanufactured tranny replacement (Kirt)
- transmission cooler replaced (Kirt)
- valve body replaced... again (Kirt)
- and have tested different ECUs, Transmission control modules, and MAF

Mucho $$$ later I haven't felt any change whatsoever, aaaah! Obviously its not the tranny, but what the problem is, I have no idea. I know my symptoms aren't the same as yours, but just a heads up... valve body isn't the answer to all 5HP30 questions, mine's been replaced three times! :/

Gees!! If it ever comes to this point, I can tell you one thing...There won't be another 5HP30 in there for long!

[Tiger]

This is really wierd as you said that tranny is a rebuilt unit... makes me wonder if it is really tranny trouble... have you check the ground cable... make sure the wire is very clean bare metal... contacting the clean bare metal of the tranny housing?

I am thinking... there usually is a ground cable... big one attached to the tranny housing by the starter... I know there is also the wire harness too... have that been checked to see if it is clean or full of filth... Either way... it does affect the reading by the computer... and cause electronic problems. Maybe this is it.

[MTechnik540i]

This is really wierd as you said that tranny is a rebuilt unit... makes me wonder if it is really tranny trouble... have you check the ground cable... make sure the wire is very clean bare metal... contacting the clean bare metal of the tranny housing?

I am thinking... there usually is a ground cable... big one attached to the tranny housing by the starter... I know there is also the wire harness too... have that been checked to see if it is clean or full of filth... Either way... it does affect the reading by the computer... and cause electronic problems. Maybe this is it.

Yeah, Kirt and I were speaking about this subject during our conversation this afternoon, so this is Plan C. Check these connections, and then some switch he was talking about. If these two things don't fix our trouble, Kirt seems to think it's time for another unit....In which case *waves* Good-bye 5HP30.

I'll keep you folks posted, thanks again for your help.