2003 5.3 4L60E Down shifting
 

When downshifting from 3rd to second and 2nd to 1st there is a noticeable "hard" down shift'
Is this something that is corrected with the computer tuning or is it in the transmission?
Up shifts are smooth and positive for all four shifts, but when slowing down for a light the 3rd to second is a bit too harsh???

Re: 2003 5.3 4L60E Down shifting
 

Stock trans, how many miles, what's the fluid look like, where's the fluid level at, stock converter?

It's much easier to diagnose a trans in person where you can look at pressure and/or log it to see what's going on. Answering the above questions may help myself or other point you in a direction though.

Re: 2003 5.3 4L60E Down shifting
 

Stock trans 75K miles, fluid and filter fresh, top of stick ,converter is factory

Thanks

Re: 2003 5.3 4L60E Down shifting
 

Do you have a different PCM laying around with the VATS deleted? Try that just to prove out that it is Tune/PCM related or not.

Anytime the Throttle is Closed the PCM will command the Lowest Line Pressure via the EPC solenoid. Which is 1.0 Amps of DC Current, Full Line Pressure is Zero Amps. This can be manually read with any Meter that can read Amps on the Positive(High) & Negative(Low) EPC wires.

Re: 2003 5.3 4L60E Down shifting
 

Yes we did switch computers first thing..........no change
O K, I am not sure where the EPC is located?

Re: 2003 5.3 4L60E Down shifting
 

The EPC is in the transmission but you can read it on pins c (high) and d (low) of the transmission plug.

Re: 2003 5.3 4L60E Down shifting
 

Is this only when you manually downshift, or does it happen on kickdown?

Re: 2003 5.3 4L60E Down shifting
 

Normal! driving when you come up to a stop sign 3rd.....clunk 2nd 1st the rpm increase "a bit" and then seems like the (torque converter did not unlock)
but nice idle 700 rpm................. upshift through the gears throttle controlled and up into the torque kicking in 45+ mph just like my other truck 2003/ 5.3 4L60E

Re: 2003 5.3 4L60E Down shifting
 

Thanks, I will have to wait on the empty rack to check that

Re: 2003 5.3 4L60E Down shifting
 

Do you have the TCC Brake wire hooked up/wired correctly?

Re: 2003 5.3 4L60E Down shifting
 

Power to TCC until the brake is pushed
I will re check the cruise control wiring also

Re: 2003 5.3 4L60E Down shifting
 

The tail lights are LED, if that makes any difference