4L80E Overdrive 4th
If the fourth clutch is not applying, then the overdrive sun gear (blue) is not held stationary, which means the overdrive carrier (red) does not "overdrive" the forward clutch housing (gold)... so you would get the same effect as being in 3rd gear.
This means that the fourth clutch piston could be getting jammed (since you said it went into 4th once, and after kickdown it would never go back into 4th unless engine was shutoff first)...
The ECM is commanding 4th gear, otherwise it would not check the input speed and set code 68.
I think May Be I got the point...
Let me check
Could also be the 3-4 shift valve sticking (see next post), this is easier to check than the 4th clutch jamming.
Also, read the note about orifice #7 and the orifice plug in the 4th clutch housing.
Thankx for nice coaprative... I'm checking these now
Still at last the Code is not removed...
8 time Repaired the Transmission...
4 Egineers came but all are faliaure.
At last I changed the transmission .. as the transmission 4L80E
the model of 98 ...
Its working very fine.
Now just showing the code of 58 of the temprature sensor.
b/coz in this model there is not temprature sensor inside...
Now what is opinion?
I think there may have been a problem with the transmission case.
4 Engineers were not able to find the cause of the problem...???
The new one works fine, that's great...
If there's no temperature sensor, find the 2 wires for this in the harness,
and connect a resistor of the right ohms to simulate 170°F-180°F or 77°C-82°C...
otherwise the ECM may set line pressure to maximum.
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