Testing the Speed Sensors in the AW55-50SN Transmission
A 2002 Volvo S60 arrived at our shop with two codes in the TCM: 0023 “Transmission input shaft speed sensor signal missing” and 0089 Transmission input speed sensor, signal too low.” The vehicle was in “limp-home mode,” which allows the transmission to be operated in 3rd and 4th gears only and with high line pressure. The customer had bought the vehicle with these conditions and did not know its history. Visual observation showed that someone had spliced into the speed sensors (Figure 1) and had replaced the transmission with a used one.
