If the Vehicle Speed Sensor (VSS) fails:
* Speedometer stops working: This is the most obvious symptom. The speedometer will likely stay at zero, regardless of your actual speed.
* Cruise control will not function: The cruise control relies on the VSS to maintain speed.
* Odometer may stop working: The odometer often gets its information from the VSS.
* ABS (Anti-lock Braking System) may malfunction: The ABS system uses the VSS for wheel speed sensing. Failure may result in the ABS light illuminating and the system not functioning correctly.
* Transmission problems (potential): Some transmissions rely on the VSS for shifting. A faulty sensor might lead to harsh shifts or transmission problems. This is less common.
* Check Engine Light (CEL): The PCM (Powertrain Control Module) will almost certainly detect a problem and illuminate the CEL, storing a diagnostic trouble code (DTC).
If the Transmission Speed Sensor (TSS) fails:
* Transmission problems: This is the main issue. The transmission may shift poorly, slip, or even fail to shift altogether. This is because the transmission relies heavily on the TSS for proper shifting strategy.
* Check Engine Light (CEL): The PCM will likely illuminate the CEL, indicating a transmission problem.
* Odometer and speedometer might still function (in some cases): The TSS is primarily used by the transmission, so other systems might not be immediately affected.
In summary: A failing speed sensor will likely cause a CEL, and at minimum, your speedometer will stop working. More severe issues, such as transmission problems or ABS malfunction, are possible depending on which sensor has failed. It's crucial to have the problem diagnosed and repaired promptly to prevent further damage and ensure safe operation of your vehicle. A mechanic can use a scan tool to identify which sensor is faulty and perform the necessary repairs.
