Where is the transmission input sensor on a 1999 Dodge Ram 1500?

The 1999 Dodge Ram 1500 doesn't have a single, easily identifiable "transmission input sensor" in the same way some vehicles have a dedicated input shaft speed sensor. Instead, the information about input shaft speed is typically derived from either the vehicle speed sensor (VSS) or the output speed sensor (OSS), sometimes in conjunction with the PCM (Powertrain Control Module) calculations. There isn't a sensor directly on the transmission input shaft itself.

To find the relevant sensors:

* Vehicle Speed Sensor (VSS): This is usually located on the rear differential, often near the axle. It sends a signal to the PCM, and the PCM uses this along with other data to infer input shaft speed.

* Output Speed Sensor (OSS): This sensor is located on the transmission output shaft (usually near the tail housing). It directly measures the output shaft speed, and the PCM uses this, along with other data, to calculate input shaft speed.

Therefore, you won't find a sensor labeled "Transmission Input Sensor". If you're experiencing transmission problems, a mechanic will need to diagnose the issue using a scan tool to check for speed sensor codes (VSS or OSS) or other transmission-related trouble codes, and then check the sensors for proper function.