6WG-260 transmission , Terex TA-30

Yazid Asaad · 2021-05-10T23:18:20.000Z

Hi all I faced a problem with a 6WG-260 Generation 1 transmission newly overhauled and I really need a help. We replace K2, Kr, K3, and K4, we checked K1, Kv and everything looks okay. We also replace the torque coverter with a used one because of the overheated marks on the old one. After starting the machine up and test it, we found the the Automatic shifting is not working all the time. Sometimes it will shift up to the sixth gear but will not down gears or reduce it 5th to 4th gear for example, so you should to change it manually to reduce gears. Sometimes it will shift from 2nd to 3rd and stuck up at the 3rd gear, even if you try to shift upward or downward, it will not shift on both Automatic and Manual. It will stuck up at the 3rd gear. The same also exactly happend at the 4th gear and few of times at the 2nd gear. During this the 3C or 39 or 3E codes shown on the display(just one code will show at time), when you totally stop the machine movement, the codes will disappear. When this problem happend, we noticed that if you move the selector N to F, it will show 6F not 2F as usual. Over one test , we drive it at uphill road ,then it start to reduce gears, 5th to 4th then to 3rd gear until the flat road then it stuck up at the third gear. The display screen start to show NN when shift from forward to reverse gear, it will not select forward or reverse gear, just will blink NN when this problem happend. We changed the gear selector, TCU(from another truck), output sensor, and turbine & internal sensor. We also found that the kickdown switch wires not connected so we connected it. We checked transmission harness and it seems okay. Could the torque converter be the reason?or the TCU, I can send a video, I hope it clear enough. Many Thanks

loczek989New MemberOct 8, 2025#22

Bigbert said: Hi NPOMBELL, I'll share manual in a pm. B7 is overtemp sump, you are right. Guess, higher than 95 degrees Celcius. When does it occur? After longhaul ride at high speed? Check oil level, set level rather lower than hot max. at dipstick. If pump creates some noise at cold start AND high rpm it doesn't matter. Check cleanliness of radiator, fan is working? Click to expand... Hello, got the same problem on long distance WS,B7 error, the gearbox need service?

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