Hello all! Im having an interesting issue with my transmission. I have an 08 4.4 zf6hp26 with the following issues. Driving in regular "D" mode the truck will shift smoothly 1,2,3, then when trying to go into 4th it will flare up thump and then stay in 3rd gear. Where it gets strange is in manual shifting mode the truck will shift perfectly normal 1,2,3,4,5,6 the truck also has no fault codes other than a suspension fault for drivers front level sensor that im waiting to come in the mail. I have experience with these transmissions but only in BMWs i have never had to deal with any transmission shifting issues in a rover product. I would assume this is a classic shift solenoid failure the only thing that makes me hesitant to take it apart and do all the seals solenoids and fluid is that it drives normal in manual mode with every failed mechatronics/Valve body I've dealt with in BMWs the transmission will fail to shift or flare bang into gear in drive sport and manual. I feel like this is more of a software TCM type issue. Would like some input from people who have dealt with a similar situation before i throw all that money and time into the truck just to have it still have the same issue because the mechanical portions were alright. The trucks got 175k miles i assume it needs a fluid change trucks new to me drove great for 100 miles and then couldn't make it to 4th pulling out of a parking lot randomly hasn't been normal since. If it is TCM related id assume these trucks are the same way as with bmws. find the used part that interchanges with your internal parts number swap them out then reset adaptations all good to go.

 

TCM would typically light up some fault lights. Abran will likely pop in shortly with more help

 

Rescanned for faults (I use an autel scanner) and it has a shadow code for lost communication with instrument cluster.

 

Thanks Bill.

Are you sure the Autel can read TCM codes? If a solenoid, it would have to have a code.

I have seen trans issues where the manual shift works fine, but in "D' there are problems. I had worn bushings and in "D" could not get above 3rd, but with manual shift I could. With your mileage a software update could be tricky, but maybe worth a chance if there are no codes.

You really need to get a GAP tool.

 

Yes autel can do anything a dealership can for the most part. Solenoids do usually have an incorrect gear ratio code corresponding to gear. What worn bushings are you referring to?

 

There are brass bushings between the gear packs. Normally the reason these trans start to slip.

 

Ah gotcha I know what you are talking about. curious as to why they wouldn’t slip in manual mode. To be fair my transmission doesn’t “slip” it’s a flare and bump into gear symptom.

 

It would slip if I didn't feather it, but when in D it would not shift past 3rd gear.

 

Have you checked the linkage on the side of the box as this is known for similar problems as it can get seized and not move properly

 

My LR3 did similar from 1-2. 2nd gear was gone. I could get it to 3rd. I ended up replacing all solenoids, valve body sleeves, pan, filter and new fluid. Reset the transmission adaptations and it is perfect now. Took several days to really do it correct. Don't forget to tap/clean the pan mount holes.