Why does 4L80E no forth or overdrive work?
Why does 4L80E no forth or overdrive work?
It will shift from 1-3 because second is forced and 1 and 3rd are done by solenoids. 4th will only work if the 2-3 solenoid gets enough pressure. So its throwing the 2-3 solenoid and tcc codes because when the fluid is hot it can’t create enough pressure and thus can’t stay in torque or 4th.
What causes OD on a 4L80 diesel?
Since your transmission has 200Ks on it the problem is likely that the valve sleeve bore has worn. When the Torque converter Solenoid strokes the piston the transmission fluid leaks past when hot. The hydraulic signal get so weak that it will no longer activate the control valve within the pump thus kicking in OD.
What does DTC 79 on a 4L80 do?
It is the Transmission Fluid Temperature Sensor. DTC 79 is transmission fluid Overtemp. A defective temp sensor will prevent overdrive. Use a multimeter between pins L and M to check for resistance. The temperature is related to resistance.
Where is the Transmission Control Module on a 4L80E?
The 4L80E Transmission system is equipped with a computer called the Transmission Control Module (TCM), located in the left/rear passenger seat compartment which interprets, ana-lyzes and records electronic signals from sensors and switches located on the engine, brake pedal, and transmission.
Is the 4L80E Trans not in overdrive?
So far, I’ve determined that its not a major internal hard part failure. In OD, truck shifts smooth through First, second and third, just wont shift to overdrive. Fluid is clean, no metal shavings, no burnt appearance or smell. To be quite honest, the trans looks great inside the pan.
Since your transmission has 200Ks on it the problem is likely that the valve sleeve bore has worn. When the Torque converter Solenoid strokes the piston the transmission fluid leaks past when hot. The hydraulic signal get so weak that it will no longer activate the control valve within the pump thus kicking in OD.
Why is the shifting valve on my 4L80 not working?
The fluid is blocked at the screen and cannot pass through the screen when the shifting solenoid is engaged. When the electricity is shut off at the computer then the check ball is allowed to back off. When this happens then the shifting valve returns. No electricity sent means no gear.
What kind of truck is a 4L80E?
I deff have a 4L80E. Its a 93 Suburban 4×4 8 lug 2500. Shes got a small block in it, but its a GVWR of 8600, and I dont see them puttin no 700R4 in that big of a truck, havent heard of that since 6.2 diesel suburbans in the 80’s.
