Why Can't an Automatic Car Shift into Reverse Gear?

[Santos]

Possible reasons why an automatic car suddenly cannot shift gears include: 1. The gear shift assembly may be faulty, preventing gear engagement; 2. The internal control module of the transmission may be malfunctioning; 3. The gear position switch of the transmission may be defective. Issues with gear engagement: 1. The positioning component of the shift lever's ball joint may have failed, allowing the shift lever to rotate freely around its axis and making it impossible to accurately control the gear position. Alternatively, the spherical working surface at the lower end of the shift lever may have worn out, preventing the shift lever from controlling the fork or the slot of the shift head, making both gear engagement and disengagement impossible. For the former issue, repairs can resolve the fault; for the latter, the shift lever must be replaced. 2. The clutch may not be fully disengaging, even though the transmission's shifting mechanism is functioning normally. This issue can be resolved by adjusting the clutch or replacing certain clutch components to ensure proper free play and disengagement clearance. 3. The shift fork may be loose, severely bent, or worn out. In this case, while the shift lever's movement is complete, the shift fork's movement is insufficient, causing severe impact and preventing gear engagement. In such situations, the transmission cover should be opened for inspection and repair, and the shift fork should be replaced if necessary.