True I'm going to re check it and see if I can see something that might be wrong

 

Another cheap check would be to make sure your alignment is OK. If thats out or the steering wheel is off center it can confuse the VSES.

If its a component thats gone bad, from what I see here the SWPS is the most common. Thats where I'd focus my attention. The accelerometers could be the issue and are easier to change as they are more accessible.

The EBCM is an expensive module and I'd leave that until last. If all else failed the EBCM can be rebuilt by absfixer at a fraction of the cost of a new one.

Document ID# 670697
2002 Chevrolet Corvette
DTC C1281, C1283, or C1286
Circuit Description

The vehicle stability enhancement system (VSES) is activated by the electronic brake control mdoule (EBCM) calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle's yaw motion by applying differential braking to the left or right front wheel.

The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error. The side slip rate error is a function of the lateral acceleration minus the product of the yaw rate and vehicle speed. The yaw rate error and side slip rate error are combined to produce the total delta velocity error. When the delta velocity error becomes too large and the VSES system activates, the drivers steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.

The VSES activations generally occur during aggressive driving, in the turns or bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the brake pedal will feel different than the ABS pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.
Conditions for Running the DTC

* C1281 The steer angle has been centered.
* The VSES is active.
* The direction (understeer or oversteer) of the delta velocity error has not changed.
* The centered lateral acceleration value is less than 0.5 g.
* The yaw rate error is less than 6 degrees/second.
* The side slip error is greater than 1.8 meters/second*second.

C1283

The vehicle speed is greater than 40 km/h (25 mph).
C1286

The steer angle has been centered.
Conditions for Setting the DTC
C1281

One of the following conditions exists:

* The VSES is engaged for 10 seconds with the delta velocity error always in either understeer or oversteer. Under this condition, this DTC will set by itself.
* The yaw rate error is greater than 10 degrees/second for 5 seconds. Under this condition, this DTC will set along with DTC C1282.
* The yaw rate error is greater than 10 degrees/second with the vehicle speed less than 60 km/h (37 mph) and the acceleration pedal is pressed more than 25 percent of the pedal travel range for 1 second during the VSES activation. Under this condition, this DTC will set along with DTC C1282.
* With the yaw rate less than 8 degrees/second, the side slip error is greater than 4.9 meters/second*second for 5 seconds. Under this condition, this DTC will set along with DTC C1284.
* With the vehicle speed greater than 10 km/h (6.2 mph) and less than 100 km/h (62 mph) and the centered yaw rate has a value that is positive and is greater than 10 degrees/second, the oversteer term is negative for 2 seconds. The oversteer term is the yaw rate value times the lateral acceleration value. Under this condition, this DTC will set along with DTC C1284.
* With the steer rate less than 80 degrees/second, the difference between the 2 steering sensor signals (Phase A and Phase B) is greater than 20 degrees for 1 second. Under this condition, this DTC will set along with DTC C1287.

C1283

The vehicle has driven for 10 minutes without completing steer angle centering.
C1286

The steering sensor bias moves greater than 40 degrees after steer centering was accomplished.
Action Taken When the DTC Sets

* The EBCM disables the VSES for the duration of the ignition cycle.
* The Traction Control and Active Handling indicator turns ON.
* The DIC displays the Service Active Handling message.
* The ABS remains functional.

Conditions for Clearing the DTC

* The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
* The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

* The scan tool may display 2 additional characters after the DTC. Take note of the 2 character code and any other DTCs that are set. The 2 character code is an engineering aid used in order to determine the specific criteria which caused the DTC to set.
* During diagnosis, park the vehicle on a level surface.
* Check the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
* Find out from the driver under what conditions the DTC was set (when the DIC displayed the Service Active Handling message). This information will help to duplicate the failure.
* The Snapshot function on the scan tool can help find an intermittent DTC.

Test Description

Perform the Steering Position Sensor Test in order to verify that the steering wheel position sensor (SWPS) is operating properly.

Verify that the lateral accelerometer input parameter is within the valid range.

Verify that the yaw rate input parameter is within the valid range.