Code 39 and 28 on a 89 buick century

Asked by Sep 30, 2017 at 03:38 PM

Question type: Maintenance & Repair

My car is a 89 buick century it was
giving me code 39, which is the torque
converter lock out. So i replaced it.  
Now i have engine code 39 and 28.  
Car runs choppy after warmed up.  If i
try passing gear or take off too hard
from stop,  she spits and pukes.
Anyone have any idea. Not real sure
what code 28 is!  

2 Answers


28 is a transmission range pressure switch error, which is either the pressure switch has failed or the fluid pressure is out of normal range,leaving the ECM unable to figure out which gear the transmission is in. Seeing the combination with the 39 code (torque converter clutch) would suggest that the problem is likely to be the torque converter clutch solenoid rather than the clutch itself. If this solenoid is dying it will have problems controlling the clutch and may randomly engage direct drive at the worst possible moments (i.e. when you try to accelerate and need the TC to actually do what it says on the box) causing the engine to (nearly) stall or lose direct drive and increase your fuel consumption.

1 people found this helpful.

But i already changed that torque converter solenoid. Where do i find the pressure switch?..i read somewhere code 28 was inside the computer. Meaning i need a new computer to fix both problems?

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