Park/Neutral Switch (Transmission Range Sensor)
The Transmission Range Sensor (TRS) is mounted to the top of the valve body inside the transaxle and can only be serviced by removing the valve body. The electrical connector extends through the transaxle case. See Fig 1 . The TRS has 4 switch contacts that monitor shift lever position and send the information to the Powertrain/Transmission Control Module (PCM/TCM). The TRS communicates shift lever position (SLP) to the PCM/TCM as a combination of open and closed switches. See Fig 1 . Each shift lever position has an assigned combination of switch states (open/closed) that the PCM/TCM receives from 4 sense circuits. The PCM/TCM interprets this information and determines the appropriate transaxle gear position and shift schedule. Since there are 4 switches, there are 16 possible combinations of open and closed switches (codes). Seven of these codes are related to gear position and three are recognized as "between gear" codes. This results in 6 codes which should never occur. These are called "invalid" codes. An invalid code will result in a DTC, and the PCM/TCM will then determine the shift lever position based on pressure switch data. This allows reasonably normal transmission operation with a TRS failure.