1996 Chevy Lumina

Start by checking tranny fluid

Sorry I am Not expert enough for you
but when you come back with a code
p0502
speed sensor circuit
I will still try to help
1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle.

2. Start engine and let idle. Shift gear selector to "D" position. Select "Output Speed" on scan tool. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, cause is intermittent.

3. Turn ignition off. Disconnect PCM Blue connector (C1). Connect voltmeter between VSS terminals at PCM Blue connector (C1). Rotate drive wheels and observe voltmeter display. If voltage is more than.5 volts, go to next step. If voltage is less than.5 volts, go to step 5.

4. Use scan tool to check for most current PCM calibration I.D. Number. Refer to manufacturer service bulletins if necessary. If I.D. Number matches, replace PCM, then go to step 8. If I.D number does not match, update PCM with latest calibration, then go to step 8.

5. Remove VSS from transaxle. Connect ohmmeter between VSS terminals. If resistance is 1300-1950 ohms, go to next step. If resistance is not 1300-1950 ohms, replace VSS, then go to step 8.

6. Install VSS into transaxle. Connect ohmmeter between VSS terminals at PCM Blue connector (C1). If resistance is less than 1300 ohms, go to next step. If resistance is more than 1950 ohms, check for open circuit between VSS and PCM. Repair as necessary, then go to step 8.
7. Check for VSS wires shorted together. Repair wires as necessary, then go to next step. If resistance is more than 1300 ohms, check for short to ground in circuits between VSS and PCM. Repair circuits as necessary, then go to next step.

8. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0502". Test drive vehicle. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.