The speedometer stopped working ? is this what you meant ? You probably have a bad VSS - vehicle speed sensor . The VSS is an input to the PCM - engine computer , besides being a signal for the speedometer it is used for shift control and other thing's .
Vehicle Speed Sensor
The vehicle speed sensor (VSS) (Figure 43) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling. You could possibly have a DTC stored in the PCM.
P0500 - Vehicle Speed Sensor (VSS) Malfunction
Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM). If the engine rpm is above the torque converter stall speed (automatic transmission) and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient vehicle speed data input, a malfunction is indicated and a DTC is set. On most vehicle applications the malfunction indicator lamp (MIL) will be triggered when this DTC is set.
- Open in VSS+/VSS- harness circuit.
- Open in TCSS signal or TCSS signal return harness circuit.
- Short to GND in VSS harness circuit.
- Short to GND in TCSS harness circuit.
- Short to PWR in VSS harness circuit.
- Short to PWR in TCSS harness circuit.
- Open or short in the vehicle speed circuit(s) (VSC) between the PCM and appropriate control module.
- Damaged VSS or TCSS.
- Damaged wheel speed sensors.
- Damaged wheel speed sensor harness circuits.
- Damage in module(s) connected to VSC/VSS circuit.
- Damage drive mechanism for VSS or TCSS.
Diagnostic Aids: - Monitor VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of VSS signal over a period of time. If vehicle speed data is lost, check source of where vehicle speed signal originates. Note TCSS does not have a PID, circuitry frequency must be checked for sudden loss of sensor signal.
P0501 - Vehicle Speed Sensor (VSS) Range/ Performance
Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. This DTC is set the same way as P0500, however the malfunction indicator lamp (MIL) is not triggered.
- Refer to possible causes for P0500.
Refer to diagnostic aids for P0500.