Transmission Range Sensor

DESCRIPTION
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.
The Transmission Range Sensor (TRS) has four switch contacts that:
- Determine shift lever position
- Supply ground to the Starter Relay in Park and Neutral only.
- Supply ground to the Backup Lamp Relay in Reverse only
The TRS also has an integrated temperature sensor (thermistor) that communicates transaxle temperature to the TCM and PCM.

OPERATION
The Transmission Range Sensor (TRS) communicates shift lever position to the TCM as a combination of open and closed switches. Each shift lever position has an assigned combination of switch states (open/closed) that the TCM receives from four sense circuits. The TCM interprets this information and determines the appropriate transaxle gear position and shift schedule.
Since there are four 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 six codes which should never occur. These are called "invalid" codes. An invalid code will result in a DTC, and the TCM will then determine the shift lever position based on pressure switch data. This allows reasonably normal transmission operation with a TRS failure.
The TRS has an integrated thermistor that the TCM uses to monitor the transmission's sump temperature. This temperature is used to determine which shift schedule the TCM is to use. If the thermistor circuit fails, the TCM will revert to calculated oil temperature usage.