ACU 523664.02 – Speed Band Switch Malfunction

ACU 523664.02 (ACU 523664.02)

Code: 523664.02

Shortcode: 523664.02


Error code ACU 523664.02 is identified when there is a conflict between Speed Band 1 and Speed Band 2 switches, where both are erroneously reading the same value. This typically indicates a malfunction in the switch mechanism or an error in the signal processing.


As a protective measure to avoid potential operational hazards due to the switch conflict, the control unit defaults the vehicle’s transmission to neutral.


  • Inspect the Speed Band 1 and 2 switches for any physical damage or misalignment that could cause identical readings. Ensure that each switch is operating independently and correctly.
  • Test the electrical connections and wiring associated with the switches to confirm that there are no shorts or cross-connections causing the identical readings.
  • Calibrate or reset the switches if your diagnostic tools indicate that this is feasible. Refer to the vehicle’s service manual for specific instructions on calibrating these switches.
  • If recalibration does not resolve the issue, consider replacing the faulty switches to restore proper function.
  • Since this code is specific to vehicles equipped with the AutoPowr/IVT left-hand reverser, verify that any repair or recalibration efforts are compatible with this system configuration.


This error is specific to models with the AutoPowr/IVT left-hand reverser option. Continuous performance monitoring and regular system checks are recommended to prevent recurrence and ensure that all switch configurations maintain their designated settings and functionality.