I have an 04 sierra 4x4 single cab 5.3L, seems my tranny is going bad but have heard a couple different things. From 1st to 2nd between shifting rpms jump up then jumps into gear also does this from 2-3rd 3-4th seems to be fine. Any answers to help would be great.
2004 4x4 tranny
- Thread starter MWOOD
- Start date
Molson02536
New member
Try replacing the TPS. or Middle case: leak in the 2nd gear apply circuit (servo assembly or 1-2 accumulator). Double check by using the pressure gauge and watch for a big drop when the PCM commands 2nd, 3rd and 4th gear. Worst case, poor line pressure rise due to leaking boost valve or clogged EPC filter screen or failing EPC solenoid, or worst case leaky seals throughout.
Start with the simple and put a line pressure gauge ( or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.490" boost valve (easy fix in pan).
And might as well have your transmission oil and filter replaced, note do not flush your transmission. The is just a 100% death of your transmission
Good luck and keep us posted.
Try replacing the Throttle Position Sensor and take a look under the car for any wet spots or stains on the ground; if so then you have to take the car immediately to the mechanic or else in future it may cost you more.