GM Service Manual Online
For 1990-2009 cars only

Ratcheting Noise

Checks

Causes

Parking Brake Pawl (50-81)

This noise may be caused by a bent parking lock actuator assembly (85). A bent actuator may not fully move the pawl (81) away from the internal reaction gear (684) when in reverse allowing the pawl to lightly contact the teeth of the internal reaction gear. The condition my not occur in forward gears as the additional actuator travel moves the pawl further from the gear teeth.

To correct this condition, replace the parking lock actuator assembly (85).