GM Service Manual Online
For 1990-2009 cars only

Checks

Causes

Line pressure solenoid

Refer to Diagnostic System Check - Vehicle.

Transmission fluid level

Refer to Transmission Fluid Check.

Select linkage

Refer Park/Neutral Position Switch Replacement.

Throttle angle

Throttle angle out of adjustment. Refer to Symptoms - Engine Controls.

Low 1-way clutch

Burn or wear of the low clutch. Refer to Low Clutch Disassemble.

Control

Control valve spool error