Do you have exact calc for tc/ah nannies?
12-27-2010, 07:13 PM
#1
Race Director
Thread Starter
Do you have exact calc for tc/ah nannies?
I use a lot of different brands/sizes of rims/tires. Does anyone have access/documentation to the exact formula?
Some work, some throw codes.
Please no approximations.
For 2004 c5z.
Thanks if you can help.
Some work, some throw codes.
Please no approximations.
For 2004 c5z.
Thanks if you can help.
12-29-2010, 06:21 PM
#2
Pro
I wonder, but don't know, if any insight would be in this SAE paper:
Chevrolet C5 Corvette Vehicle Dynamic Control System
Here's the abstract:
Edit: Hmmm.... This paper was released in 1998 so it may not apply to 2nd generation system in your 2004. Maybe you could track down the authors somehow and ask them.
Chevrolet C5 Corvette Vehicle Dynamic Control System
Here's the abstract:
This paper will explain the C5 Corvette Active Handling (AH) control strategy formulated around the base vehicle characteristics and additional integrated components. The new chassis control strategy uses electrohydraulic brake pressure at all four corners to input braking forces independent of the driver. AH was designed to assist the driver in controlling the vehicle during limit handling situations. The primary inputs to the chassis control strategy are vehicle speed, steering wheel angle, yaw rate about a vertical axis passing through the vehicle's c.g., brake pressure and lateral acceleration.
12-29-2010, 08:04 PM
#4
Pro
Sure thing. I hope it is helpful.
If you go to sae.org and use "Corvette" as a search term, you will find that GM has allowed their engineers to publish a number of papers about our cars over the years.
If you go to sae.org and use "Corvette" as a search term, you will find that GM has allowed their engineers to publish a number of papers about our cars over the years.
12-29-2010, 09:26 PM
#5
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I have that paper. It provides a detailed description of what they do but not a lot of implementation (how) details. I doubt the newer version of AH works any differently than what is described in that paper.
I suspect there is some variation between EBCMs. I know some people had traction control issues if they ran equal diameter tires front and rear. I could do that with my 03Z running 710s and not have any issues. If I drove home from an autocross on the 710s I could run 60 or 70 miles without TC activating. Other people had problems within a short distance. I do know TC will activate almost instantly if you swap your stock front and rear wheel/tire setup. It will even activate the rear brakes while coasting down hill in nuetral.
AH doesn't depend on tire diameter as it is activated by comparing cornering Gs and actual yaw rate Vs intended yaw rate. AH only needs to read the wheel speed of the wheel it is braking to determine when it is in a lock up state.
Bill
I suspect there is some variation between EBCMs. I know some people had traction control issues if they ran equal diameter tires front and rear. I could do that with my 03Z running 710s and not have any issues. If I drove home from an autocross on the 710s I could run 60 or 70 miles without TC activating. Other people had problems within a short distance. I do know TC will activate almost instantly if you swap your stock front and rear wheel/tire setup. It will even activate the rear brakes while coasting down hill in nuetral.
AH doesn't depend on tire diameter as it is activated by comparing cornering Gs and actual yaw rate Vs intended yaw rate. AH only needs to read the wheel speed of the wheel it is braking to determine when it is in a lock up state.
Bill
01-14-2011, 07:58 PM
#7
Race Director
Thread Starter
I am getting occasional codes service tc/ah when I first start driving & tc/ah turns off.
Tire sizes are
F 25.4 dia R 26.4
Stock sizes are
F25.4 R 26.1
I would have thought this is close enough to stock that I would not have issues.
Tire sizes are
F 25.4 dia R 26.4
Stock sizes are
F25.4 R 26.1
I would have thought this is close enough to stock that I would not have issues.
01-15-2011, 03:37 PM
#9
Race Director
Thread Starter
Once a drive, and it stays on the whole drive. Then next ignition cycle it clears & then next day or two comes back same. It may be the steering position sensor.
Would still like that tire size spreadsheet if anyone has.
Would still like that tire size spreadsheet if anyone has.
01-16-2011, 02:07 AM
#10
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Bill
01-16-2011, 02:19 PM
#11
Race Director
Thread Starter
It's 1288 I think the problem is the connection going to the steering wheel position sensor. I took it apart & inspected it & put back together with silicone tape to minimize movement in the connection.
I found a c6 thread about the problem in those cars & while I just get a code & message to service, the c6 locks up a brake, ouch.
It may be fretting.
http://www.underhoodservice.com/Arti...ff_anyway.aspx
Or a bad SWPS.
Thanks.
I found a c6 thread about the problem in those cars & while I just get a code & message to service, the c6 locks up a brake, ouch.
It may be fretting.
http://www.underhoodservice.com/Arti...ff_anyway.aspx
Or a bad SWPS.
Thanks.
01-16-2011, 03:03 PM
#12
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Dtc c1288
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
The ignition is ON.
Conditions for Setting the DTC
C1287
One of the following conditions exists:
The steering wheel position sensor is synchronized and the steer rate (speed that the steering wheel appears to be turning) is greater than 1100 degrees/second.
The steer rate is less than 80 degrees/second and the difference in the phase angle between Phase A and Phase B is greater than 20 degrees.
The 2 steering sensor signals (Phase A and Phase B) do not agree for 1 second. Under this condition, this DTC will set along with DTC C1281.
C1288
One of the following conditions exists:
Both Phase A and Phase B are greater than 4.9 volts for 1.6 seconds.
Both Phase A and Phase B are less than 0.2 volts for 1.6 seconds.
The difference in the changes in Phase A and Phase B is greater than 35.2 degrees for 9.76 milliseconds.
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
The numbers below refer to the step numbers on the diagnostic table.
Perform the Steering Position Sensor Test in order to verify if the steering wheel position sensor (SWPS) is operating properly.
Tests for the proper operation of the steering wheel position signal A circuit in the low voltage range.
Tests for the proper operation of the steering wheel position signal B circuit in the low voltage range.
Tests for the proper operation of the steering wheel position signal A circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
Tests for the proper operation of the steering wheel position signal B circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
Tests for a short to voltage in the 5-volt reference circuit.
Tests for a high resistance or an open in the low reference circuit.
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
The ignition is ON.
Conditions for Setting the DTC
C1287
One of the following conditions exists:
The steering wheel position sensor is synchronized and the steer rate (speed that the steering wheel appears to be turning) is greater than 1100 degrees/second.
The steer rate is less than 80 degrees/second and the difference in the phase angle between Phase A and Phase B is greater than 20 degrees.
The 2 steering sensor signals (Phase A and Phase B) do not agree for 1 second. Under this condition, this DTC will set along with DTC C1281.
C1288
One of the following conditions exists:
Both Phase A and Phase B are greater than 4.9 volts for 1.6 seconds.
Both Phase A and Phase B are less than 0.2 volts for 1.6 seconds.
The difference in the changes in Phase A and Phase B is greater than 35.2 degrees for 9.76 milliseconds.
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
The numbers below refer to the step numbers on the diagnostic table.
Perform the Steering Position Sensor Test in order to verify if the steering wheel position sensor (SWPS) is operating properly.
Tests for the proper operation of the steering wheel position signal A circuit in the low voltage range.
Tests for the proper operation of the steering wheel position signal B circuit in the low voltage range.
Tests for the proper operation of the steering wheel position signal A circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
Tests for the proper operation of the steering wheel position signal B circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
Tests for a short to voltage in the 5-volt reference circuit.
Tests for a high resistance or an open in the low reference circuit.
01-16-2011, 03:04 PM
#13
Drifting
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Here's what the Manual Says about TCS/AH for a '04
Traction Control System (TCS) (NW9)
When drive wheel slip is noted while the brake is not applied, the EBCM will enter traction control mode.
First, the EBCM requests the PCM to reduce the amount of torque to the drive wheels via the requested torque signal circuit. The PCM reduces torque to the drive wheels by retarding spark timing and turning off fuel injectors. The PCM reports the amount torque delivered to the drive wheels via the delivered torque signal circuit.
If the engine torque reduction does not eliminate drive wheel slip, the EBCM will actively apply the drive wheel brakes. During traction control braking, hydraulic pressure in each drive wheel circuit is controlled to prevent the drive wheels from slipping. The master cylinder isolation valve closes in order to isolate the master cylinder from the rest of the hydraulic system. The prime valve then opens in order to allow the pump to accumulate brake fluid in order to build hydraulic pressure for braking. The drive wheel inlet and outlet solenoid valves then open and close in order to perform the following functions:
Pressure hold
Pressure increase
Pressure decrease
Vehicle Stability Enhancement System (VSES)
The vehicle stability enhancement system (VSES) includes an additional level of vehicle control to the EBCM. The VSES is activated by the 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 driver's steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.
The EBCM also uses the input from the brake fluid pressure sensor for more accurate braking control during VSES.
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.
Rear Stability Control
When the vehicle performs a high speed turn or curve, the EBCM will enter rear stability control mode. The vehicle speed is greater than 48 km/h (30 mph) and the vehicle lateral acceleration is greater than 0.6 g. The vehicle will exit rear stability control when the vehicle speed is less than 40 km/h (25 mph) or the vehicle lateral acceleration is less than 0.4 g.
During a rear stability control event, the EBCM performs a pressure increase on the outside rear brake and a pressure hold on the inside rear brake. The driver may hear the pump motor run and may feel a vibration in the brake pedal.
When drive wheel slip is noted while the brake is not applied, the EBCM will enter traction control mode.
First, the EBCM requests the PCM to reduce the amount of torque to the drive wheels via the requested torque signal circuit. The PCM reduces torque to the drive wheels by retarding spark timing and turning off fuel injectors. The PCM reports the amount torque delivered to the drive wheels via the delivered torque signal circuit.
If the engine torque reduction does not eliminate drive wheel slip, the EBCM will actively apply the drive wheel brakes. During traction control braking, hydraulic pressure in each drive wheel circuit is controlled to prevent the drive wheels from slipping. The master cylinder isolation valve closes in order to isolate the master cylinder from the rest of the hydraulic system. The prime valve then opens in order to allow the pump to accumulate brake fluid in order to build hydraulic pressure for braking. The drive wheel inlet and outlet solenoid valves then open and close in order to perform the following functions:
Pressure hold
Pressure increase
Pressure decrease
Vehicle Stability Enhancement System (VSES)
The vehicle stability enhancement system (VSES) includes an additional level of vehicle control to the EBCM. The VSES is activated by the 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 driver's steering inputs combined with the differential braking will attempt to bring the delta velocity error toward zero.
The EBCM also uses the input from the brake fluid pressure sensor for more accurate braking control during VSES.
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.
Rear Stability Control
When the vehicle performs a high speed turn or curve, the EBCM will enter rear stability control mode. The vehicle speed is greater than 48 km/h (30 mph) and the vehicle lateral acceleration is greater than 0.6 g. The vehicle will exit rear stability control when the vehicle speed is less than 40 km/h (25 mph) or the vehicle lateral acceleration is less than 0.4 g.
During a rear stability control event, the EBCM performs a pressure increase on the outside rear brake and a pressure hold on the inside rear brake. The driver may hear the pump motor run and may feel a vibration in the brake pedal.
