Hey Drivers,

I am having some issues with my Vette that are keeping it in the garage. It is a 2008 base model, 6 speed manual.

Last week I was driving my car up my driveway, which is somewhat of a slope. I am in first gear pulling up the driveway and I get a "SERVICE TRACTION SYSTEM" message in my dashboard. I then tried to reverse the car to drive it later that day, and I couldn't get the car into the reverse gear.

I plugged an ODB 2 reader into the data port under the steering wheel and got a P0502 message "Vehicle Speed Sensor A Circuit Low" is this causing the reverse lockout solenoid to engage? Can I switch out the sensor and be good to go? Or is it something that can be resolved by cleaning the contacts on the sensor?

I did some searching on here before I made this post trying to find the answer, but I was unable to find any posts that were a duplicate issue of what I am experiencing. Any help would be greatly appreciated. I do not want to be forced to get the car towed to the dealer for repairs if it is as easy as replacing one sensor.

I have attached a couple of images below to help illustrate exactly what I saw when I was troubleshooting this issue.

Thanks in advance for the help.

 

P0502 is normally the VSS sensor in the top of the diff going south, or connector unplugged, and just needs to be replace or connector and socket pins cleaned and the connector plugged back in.

Black sensor on top of the diff is the VSS, and so could be a bad connection at the sensor connector, or just the sensor bad isntead.


As for the car locking the trans out of reverse, since the ECM can not get a Zero speed reading to make sure that car is not moving, this may be the reason for that,
To add to this, although the reverse solenoid has engaged, you can brute force your way past it via the shifter to get the car into reverse, or just disconnect the battery to power off the solenoid, put the car into reverse, then re-connect the battery

As for testing,
Circuit/System Testing
Disconnect the ECM harness connector X1.
Measure for 1,300-1,500 ohms at 25°C (77°F) between the VSS high signal circuit terminal 71 and the VSS low signal circuit terminal 72.
⇒ If the value is greater than 1,500 ohms test the VSS high signal circuit and the VSS low signal circuit for an open/high resistance. If the circuits/connections test normal, replace the vehicle speed sensor.

⇒ If the value is less than 1,300 ohms test the VSS high signal and the VSS low signal circuits for a shorted together condition. If the circuits/connections test normal, replace the vehicle speed sensor.

Measure for more than 10 ohms of resistance between the VSS high signal circuit terminal 71 and ground.
⇒ If the value is less than the specified range, repair the short to ground.

Measure for more than 10 ohms of resistance between the VSS low signal circuit terminal 72 and ground.
⇒ If the value is less than the specified range, repair the short to ground.

Reconnect the ECM connector. Disconnect the VSS connector.
Ignition ON, test the VSS high signal circuit terminal B for a short to voltage.
⇒ If all circuits/connections test normal, test or replace the VSS.