GM Service Manual Online
For 1990-2009 cars only

Oil Pressure High or Low

Checks

Causes

ECM Torque Related DTCs are set

DTCs can cause the engine torque value used by the TCM to become invalid. When the engine torque is invalid, the TCM will command maximum line pressure to protect the transmission.

Oil Pump Assembly (4)

    • Pressure regulator valve stuck
    • Pressure regulator valve spring
    • Rotor guide omitted or misassembled
    • Rotor cracked or broken
    • Reverse boost valve or sleeve stuck, damaged or incorrectly assembled
    • Orifice hole in pressure regulator valve plugged
    • Sticking slide or excessive rotor clearance
    • Pressure relief ball not seated or damaged
    • Porosity in pump cover or body
    • Wrong pump cover
    • Pump faces not flat
    • Excessive rotor clearance

Oil Filter (72)

    • Intake pipe restricted by casting flash
    • Cracks in filter body or intake pipe
    • O-ring seal missing, cut or damaged
    • Wrong grease used on rebuild

Control Valve Body (60)

    • Manual valve scored or damaged
    • Spacer plate or gaskets incorrect, misassembled or damaged
    • Face not flat
    • 2-3 Shift valve stuck
    • Checkballs omitted or misassembled

Pressure Control Solenoid (377)

Damage to electrical terminals

Transmission Fluid Pressure Manual Valve Position Switch (69)

    • Contamination
    • Damaged seals

Case (103)

Case to control valve body face not flat

System Voltage

    • 12 volts not supplied to transmission
    • Electrical short (pinched solenoid wire)
    • Solenoid not grounded