GM Service Manual Online
For 1990-2009 cars only

Condition

Action

DEFINITION: Vehicle moves in D, I and L, but not in the R position, or the vehicle moves forward in the R position

    • Reverse shift fork shaft stuck
    • Modulator valve inoperative
    • Reverse CPC valve inoperative
    • 5th accumulator inoperative
    •  5th clutch inoperative
    • Reverse gears worn or damaged
    • Inspect the line pressure and the 5th clutch pressure.
    • Inspect for a missing reverse shift fork bolt on the reverse shift fork shaft.
    • If the ATF filter is clogged with particles of steel or aluminum, inspect the ATF pump. If the ATF pump is in satisfactory condition, and no cause for the contamination is found, replace the torque converter.
    • Inspect the reverse synchronizer gear teeth chamfers,
    • Inspect the engagement teeth chamfers of the output shaft 5th gear and reverse gear. Replace the reverse gears and the reverse synchronizer if they are worn or damaged.
    • Replace the mainshaft 5th gear, the reverse idler gear, and the output shaft 5th gear, if the transmission makes clicking, grinding, or whirring noises.
    • Inspect the clutch piston, the clutch piston check valve, and the O-rings.
    • Inspect the clutch piston spring retainer for wear and damage.
    • Inspect the clutch backing plate-to-top disc clearance. If the clearance is out of tolerance, inspect the clutch discs and plates for wear and damage. If the discs and plates are worn or damaged, replace the discs and plates as a set. If the discs and plates are in satisfactory condition, adjust the clearance with the clutch backing plate.