2001 chevy z71 4x4 got the co236 rear wheel speed circuit, i replaced both vss sensors now agrevated did nothing has a brand new jasper rebuilt tranny showing abs light and parking brake light will stay in 1st gear until maually shifted into 2nd then if 3rd or 4th or drive it just drops to 1st ? speedometer does not work as well

Question edited for clarity.
Question moved to model category.

The speed sensors on the wheel are wheel speed sensors and are only for the ABS system.

https://www.google.com/search?q=2001+Ford+Sport+Trac%2C+2+wheel+drive.+The+speedometer+and+odometer+are+not+working

More here and videos

https://www.google.com/search?q=2001+Ford+Sport+Trac%2C+vehicle+speed+sensor+VSS

..

You should look for a qualified repair shop , unless you know how to test automotive electrical circuits . Battery drain or parasitic draw on the battery is not easy to find if not familiar with automotive electrical testing . Also having wiring diagrams an service repair info . Does the truck run an drive ok ? The speedo an tach not working could be a problem inside the instrument cluster or VSS - vehicle speed sensor for the speedometer .
Vehicle Speed Sensor (VSS)
On vehicles equipped with 4-wheel anti-lock brake systems (4WABS), the vehicle speed signal is generated by the rear anti-lock brake sensor and sent to the 4WABS module. The 4WABS module sends the vehicle speed signal via circuit 679 (GY/BK) to all systems that require a vehicle speed signal input. Vehicles equipped with rear anti-lock brakes (RABS) generate a vehicle speed signal from the rear axle speed sensor. The generic electronic module (GEM) receives this signal (VSS_GEM) for internal use and then distributes it to the appropriate other users (i.e., the powertrain control module [PCM], speed control module, and speedometer).
Speedometer
The electronic speedometer (17255) receives a speed signal from the 4WABS module (if equipped with 4WABS) or the generic electronic module (GEM)/central timer module (CTM) (if equipped with RABS).

Tachometer
Gasoline vehicles are equipped with a 6,000 rpm tachometer and diesel vehicles are equipped with a 4,500 rpm tachometer. The tachometer is hardwired to the PCM through circuit 648 (WH/PK).

https://www.youtube.com/watch?v=efKoWifdcag&t=844s

https://www.youtube.com/watch?v=6xFo_oHFF48&t=2056s

Was there a trouble code listed with problem, if so, what was the code? I'm aware of wheel speed sensors and I'm aware of vss, if there is another one, then I'm not aware.

The vss/vehicle speed sensor should be located in halfshaft housing for transaxle.

The wheel speed sensors are usually located at the wheels.

taking your vehicle to a qualified reair shop to have it diagnosed would be a good thing to do . You could not have traced all wires ! Because i'm sure you haven't any idea how this works . An a factory scan tool is a must to diagnose this .Do you know what ford SCP data network is ?
Speedometer
The instrument cluster receives the vehicle speed signal from the powertrain control module (PCM) over the standard corporate protocol (SCP) network and displays it on the speedometer gauge. If the instrument cluster receives no vehicle speed signal after one second, the speedometer defaults to 0.0 km/h (0.0 mph).

Vehicle Speed Sensor
The vehicle speed sensor (VSS) (Figure 52) 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.

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), the transfer case speed sensor (TCSS) or the anti-lock brake system (ABS) control module. If the engine RPM is above the torque converter stall speed (automatic transmission) and the 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) is triggered when this DTC is set.

• Open in the VSS+/VSS- harness circuit.
• Open in the TCSS signal or the TCSS signal return harness circuit.
• Short to GND in the VSS harness circuit.
• Short to GND in the TCSS harness circuit.
• Short to PWR in the VSS harness circuit.
• Short to PWR in the TCSS harness circuit.
• Damaged drive mechanism for VSS or TCSS.
• Damaged VSS or TCSS.
• Damaged wheel speed sensors.
• Damaged wheel speed sensor harness circuits.
• Damage in the module(s) connected to the VSC/VSS circuit.
• Open or short in the vehicle speed circuit VSS signal between the ABS VSS signal output and the VSS signal inputs to the PCM and other modules (Excursion and F-Super Duty).

Monitor the VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of vehicle speed signal over a period of time. If vehicle speed data is lost, check the source of where the vehicle speed input originates from: VSS, TCSS or ABS. Note: On some MSOF applications, VSS and TCSS PID can be monitor. However if no TCSS PID is available and VSS PID is zero, TCSS circuitry frequency must be checked for loss of sensor signal. If another vehicle electronic module has generated the P0500 and the vehicle does not receive its vehicle speed input from one of the above mention sources (VSS, TCSS or ABS). Check the PCM for Output Shaft Speed Sensor (OSS) DTCs. On OSS applications the PCM uses the OSS to calculated the vehicle speed. If no OSS DTCs are found check for correct PCM configuration. Check PCM configuration for correct tire size and axle ratio. 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. P0503 - Vehicle Speed Sensor (VSS) Intermittent Indicates poor or noisy VSS performance. Vehicle speed data is received from either the vehicle speed sensor (VSS), the transfer case speed sensor (TCSS), or the anti-lock brake system (ABS) control module.

• Noisy VSS/TCSS input signal from the radio frequency interference / electro-magnetic interference (RFI/EMI) external sources, such as ignition components or the charging circuit.
• Damaged VSS or driven gears.
• Damaged TCSS.
• Damaged wiring harness or connectors.
• Malfunction in the module(s) or circuit connected to the VSS/TCSS circuit.
• After market add-on.

Monitor the VSS PID while driving the vehicle. Check for intermittent vehicle speed indication. Verify the ignition and charging system are functioning correctly.

The speedometer provides speed information based on a speed/distance pulse signal from the vehicle speed sensor (VSS). The VSS is mounted on the speedometer driven gear in the transmission.
or the gauge is bad .

• The speedometer/odometer is inoperative

• CJB fuse 14 (10A).
• Vehicle speed sensor (VSS).
• Circuitry.
• Instrument cluster.

• Go To Pinpoint Test E .

PINPOINT TEST E: THE SPEEDOMETER/ODOMETER IS INOPERATIVE CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.
CONDITIONS DETAILS/RESULTS/ACTIONS E1 CHECK VSS SPEED SIGNAL BETWEEN CIRCUITS 679 (GY/BK) AND CIRCUIT 676 (PK/OG)
VSS C1088
Raise the drive wheels off the ground. While rotating the driveshaft, measure the AC voltage between the VSS C1088 pin 1, circuit 679 (GY/BK), component side and the VSS C1088 pin 2, circuit 676 (PK/OG), component side.

• Is the voltage between 1.3 volts AC to 6.1 volts AC?

Yes GO to E2 .

No CHECK and INSPECT the speedometer drive gear. INSTALL a new VSS if the speedometer drive gear is OK. TEST the system for normal operation E2 CHECK CIRCUIT 679 (GY/BK) AND CIRCUIT 676 (PK/OG) BETWEEN THE INSTRUMENT CLUSTER AND THE VSS

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.

code p0500 refers to vehicle speed sensor(VSS) --circuit malfunction====causes--wiring-- VSS --ECM
The VSS is normally located in/at the rear of the gear box.

Faulty rear wheel speed sensor.You can reset the computer with a code reader or a scan tool then test drive it.If problem comes back then replace the rear wheel speed sensor.You will have to test them to figure out which one is faulty.

Codes indicate rear wheel speed sensor fault, this part of ABS system. A mechanic will need to inspect sensors.

Vehicle Speed Sensor fault

There are three parts of the Vehicle Speed Sensor (VSS) circuit; the VSS, the Powertrain Control Module (PCM) and the wiring between the two. The problem could be in any one, or more, of these parts.
The most likely problem would be with the VSS itself. You can check the VSS signal with a DVOM set to read AC volts. Raise the front wheels off the ground and support the vehicle with jack stands. Never, ever work on a vehicle that is supported by a jack alone. Having a vehicle fall on your chest could ruin your whole day.
Connect the leads of the DVOM to the yellow, C1-64 and purple, C1-65 wires of connector C1 (blue) of the PCM. Be very, very careful you do not damage the connections of the wires. I use a single strand of a multi-strand wire to insert into the connector then connect my leads to that. There is an electrical test kit you can buy but the single strand wire will do quite nicely in a pinch.
Put the key in the ON engine OFF position, place the transmission in DRIVE or NUETRAL and slowly rotate the right front wheel. You should get a reading of 0.4 volts AC. If the reading is good set your DVOM to ohms and measure the resistance of the whole circuit. It should read between 1650 to 3180 ohms. If not you have a problem in the wiring. If both check out good, then the problem is in the PCM.
The PCM will run about $321.45 and about an hour labor to replace and reprogram. The VSS will run about $35.17 and about a half hour to replace. Figure about one hour labor to diagnose the problem. If the problem is in the wiring; that is charged by the actual time it takes to locate and repair the problem.
The VSS is located on the end of the transmission. Remove the right front tire and you will see it. To replace it simply unplug the connector, remove the attaching bolt and remove the VSS from the transmission. Then install the new one, secure the attaching bolt and plug in the connector. Simple as that.


Read more at Suite101: Chevy Impala DTC P0502: 2001 Chevy Impala With A DTC Of P0502 http://autotechrepair.suite101.com/article.cfm/chevy_impala_dtc_p 0502#ixzz0btZFK0Ma
Lone88star


Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/jason_77a19afa8d604dee