Gear motor wiring is damaged or has an intermittent connection.
Gear motor is bad.
Gear motor target is damaged.
Lower PCA is bad.
Disconnect power from the unit. Remove the F2 fuse from the lower PCA. Using an ohmmeter, measure the fuse for 1 ohm or less. If the reading is considerably high, replace the fuse. If the fuse is blown, inspect further for the cause to avoid the fuse blowing again. Inspect for damaged gear motor wiring or a bad gear motor. Replace if necessary.
Thoroughly inspect the gear motor wiring for damage or intermittent connections. Repair or replace damaged wiring or poor connections as necessary.
With the unit disconnected from power, disconnect both wires from the gear motor. Using an ohmmeter, check for approximately 9 ohms through the gear motor wiring. If the reading is considerably high or low, replace the gear motor.
Inspect the gear motor target for rips, tears, or bad scratches. If any of these are found, replace the target.
During the start-up sequence, check the voltage at the gear motor. Voltage should be approximately 12VDC. The voltage should only be present between the time the sequence was started and the error 53 occurred. If the voltage is considerably low or absent and the F2 fuse proved good, replace the lower PCA.