GM Service Manual Online
For 1990-2009 cars only

Incorrect Line Pressure

Checks

Cause

DEFINITION: Transmission main line pressure that is determined to be high or low. Refer to Line Pressure Check .

Automatic transmission fluid level (low pressure only)

Low fluid level

Thermo element assembly (low pressure only)

    • The thermo element plate pins (120, 123) are misadjusted
    • The thermo element (121) or the thermo element plate (122) is out of position, missing, or damaged -- causing low fluid level in the oil pan

Oil filter and seal assembly

    • The oil filter assembly (100) is missing or damaged
    • The oil filter seal assembly (101) is missing or damaged (low pressure only)

Wiring harness assembly

The wiring harness assembly (224) is disconnected or damaged

Oil pump assembly

    • The following components are worn or damaged (low pressure only):
       - the oil pump cover (201)
       - the oil pump body (202)
       - the oil pump vane ring (209)
       - the oil pump rotor (210)
       - the oil pump vanes (211)
       - the oil pump slide oil seal ring (212)
       - the oil pump slide O-ring seal (213)
       - the oil pump slide (214)
    • The oil pump slide (214) is binding (high pressure only)
    • The oil pump prime springs (222, 223) or the oil pump slide pivot pin (215) is missing or damaged (low pressure only)
    • The oil pump slide seal (220) or the oil pump slide seal support (221) is missing or damaged (high pressure only)

Pressure control solenoid valve assembly

    • The pressure control solenoid valve assembly (322) is damaged
    • The solenoid valve O-ring seals (305, 316) are missing or damaged
    • The valve retainer (314) is missing or damaged

Torque signal regulator valve assembly

    • The torque signal regulator valve (321) is binding or damaged
    • The valve retainer (314) is missing or damaged

Pressure regulator valve assembly

    • The pressure regulator valve (313) is binding or is damaged
    • The pressure regulator valve springs (311, 312) is missing or damaged
    • The reverse boost valve (310) is binding or is damaged (high pressure only)
    • The line boost valve (304) is binding or is damaged (high pressure only)
    • The valve retainer (302) is missing or is damaged

Actuator feed limit valve assembly (low pressure only)

    • The actuator feed limit valve (414) is binding or is damaged
    • The actuator feed limit valve spring (415) is missing or is damaged
    • The actuator feed limit valve spring retainer (416) is missing or damaged

Low blow off valve assembly (low pressure only)

    • The low blow off valve spring (323) is missing or is damaged
    • The low blow off ball valve (324) is missing, binding, or is damaged
    • The low blow off valve spring retainer (325) is missing or is damaged