Transmission will not shift into high gear
Before guessing at transmission problems, check the fluid level (car warmed up, engine running in Park on level ground) and have the PCM scanned for trouble codes FIRST. This guide is meant for problems that do not show up as PCM codes (like shift A&B solenoid failures, for example).
Also note that many problems that show up as transmission issues are actually PCM or electrical, and may be external to the transmission. Try a different PCM, and check for chafing where the cables come out of the PCM.
What is "limp-home mode" ? This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. The transmission will default to max line pressure. The driver will have Reverse and 3rd, with manual 2nd available by putting the gearshift in 2 or 1 (doesn't matter). 1st, 4th, and TCC lockup will not be available. It will not hurt the car to drive it like this for short periods, but use manual 2nd to get the car moving, and be aware that the trans will generate more heat than normal while operating in limp-home mode due to increased torque converter slippage during 2nd gear starts and no lockup in 3rd gear.
No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
Trans shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmision is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the underhood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.
Thank you for using fixya and good luck. Check all your fuses first to ensure it's not a simple as that before you take it to a transmission shop. Call around, most transmission shop will scan free of charge to inspect the condition of your transmission.
95 chevy4x4 wont shift out of 2nd gear and feels like it shifts into nuetral, at times. replaced speed sensor and ign sw but at no advantage. most times truck shifts finr but when it dosent it will after shutdown truck couple mins and restart go on, can be real pain.
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