Incorrect Line Pressure

WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.

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