Took it to trans should for code P1810. They replaced the TFP Valve position switch circuit with same part from my old trans and it's now perfect.

Case closed. Hope this trans lives long. I will need to get billet output shaft for later shaft change.

 

Well, code P1810 showed up again and it started acting again @ 80mph, locking and unlocking TC. It happens repeatedly alternating until I accelerate higher.

Also, it shifts very hard from N to D that I can here the sound of it kicking and feel it jumping even with brake pedal pressed hard.

Any idea about the issue? Is it mechanical/electrical inside the trans or in the tune??

 

Als, Transmission started acting at high RPM in 4th gear. At around 90-100mph, it would suddenly rev to limiter 6200 as if it is in neutral.

If I slow down then try to accelrate slowly, it would not do it. Only at hard acceleration near full throttle to would act as if it's suddenly going in neutral.

Could this be bad clutch, sprag or what?

I am taking it back to the transmission shop.

It's frustrating that this is never used level 4L65E. I only replaced the 2WD output shaft with my truck stock 4WD output shaft.!!

However, the tranmission was sitting on the floor for more than two or three years. We checked the oil in the trnamission before draining it to swap the output shaft and looked good.

So, two issues with this transmission:

-locking and unlocking in 4th gear at 80-90mph
-Slipping bad in 4th at 100mph.

 

P1810 is either an internal pressure leak or electrical fault in the transmission fluid pressure switch (an almost bulletproof switch) or circuits. Outside chance of a bad park/neutral switch confusing the PCM. Have seen t/converters set 1810's.

 

Does this mean no need to tear the transmission to fix it??

It's now in the tranmission shop to check things. Hopefully will have it back on the road and will search for 4L80E for the swap.

 

Indeed, it was electrical fault. The transmission harness has a short and it was resolved by puting insulation on the harness.

Now it does not slip at full throttle. Howver, it stays in third and does not shift into 4th until I press the tow button at the shifter by the steering column.

Since I remember my tuner saying he tuned it to shift certain speed when the tow button is pressed, I will take it to the tuner to check why it shift doesn't shift into 4th until the tow button is pressed.

Also, I bought a billet a used billet 4WD output shaft from a member on this forum. Will install it later or if I break the stock output shaft.

 

It threw code P1810 again. Also, doesn't shift to 4th unless I babe it in 3rd through 4th!!!! It does it on and off.

Changing plan, will not take to tuner. I am taking it back to transmission shop after I receive the output shaft, next week, to go through the whole transmission again and install the billet output shaft.

I hope someone, other than me, is enjoying this 4L60E story.

 

Waiting for the billet output shaft to arrive. Meanwhile, I still get the P1810 code - TFP Valve Position Switch Circuit.

Sometime it shift into 4th and sometime it doesn't. I noticed that my Aeroforce interceptor gauge shows trans oil temp (3 digits number, 155-170F) when it shifts but when it acts and doesn't shift into 4th, the reading shows incorrect reading (5 digits number like 65423F).