I have a 94 GMC Safari which the vehicle is slow when accelerating - it also shifts hard/ and won't shift from 2nd gear - 4th without letting off the gas, otherwise engine continues to rev up and knocks the trans into following gear. 1st shift is fine. What is causing this, and how to fix it without spending alot.
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Hi, I exactly I have a gmc 2002 envoy and I have exactly this problem and we just change the oil and all transmission sensor and is still doing it so what problem can be thank you
Note:
This process must be carried out in normal mode (not sports mode). On a
flat road, the transmission fluid temperature must be above 60° C (140°
f) and below 100° C (212° f) (vehicle at normal operating temperature
will ensure that the transmission fluid temperature is above 60° C (140°
f)).
9. Accelerate from rest with
light throttle (do not exceed the upper rev limit in appendix 1). 1-2,
2-3, 3-4 shifts must occur with engine speed between the following
limits:. Note: Do not move the accelerator pedal during shifts.
10. Continue to accelerate gently to 50 mph (80 km/h) so that transmission shifts into 5th gear.
11. Go into overrun and let the transmission shift down into 4th gear without braking.
12. Brake gently to a standstill and hold footbrake on for at least 15 seconds.
13. This process should be carried out at least five times.
Page 2 of 3 Bulletin Number S307-17 ________________________________________________________________________________
Shift suddenly become very hard. When going from park to either
reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh.
All gears seems to work. Problem may be intermittent: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
Extremely harsh shifts from P or N, normal shifts at WOT: EPC
(Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as
soon as possible or hard parts will eventually break.
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.
Car goes into gear but feels very sluggish like the brakes are dragging,
but it will roll easily (starts out in 4th gear), you manually shift to
2 to get it moving, once it's moving you put it back in OD and the car
shifts 3rd to 4th on its own and locks the converter at the appropriate
time: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem
from PCM to trans.. or PCM.
Your problem likely resides with the hydraulic valve that operates the band for second gear, or lack of hydraulic pressure in the transmission. If the actuator in the transmission that operates second gear is getting sticky, then it will cause this. A filter change and flush may help, but it's likely time to start looking for someone to tear down your transmission, or replace it.
Check that the OD solenoid on the torque converter is good still. When the R4 wont go into OD you have no more gears than 1st an 2nd. If the OD clutch drum was relaced if it was burnt, that will make a problem also. You have to have OD in order for these babies to work right.
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