CySevans

Help!

https://ls1tech.com/forums/showthrea...69#post2853869

This is on my mother-in-law's 2001 coupe.

Thanks!

IRace2ChevyII

Take it to the top

CySevans

I found this to be extremely helpful:

http://www.stengel.net/diccodes.htm

With this, I pulled the DIC codes and found a C1288 in the TCS system.

Oddly, the above list doesn't show a C1288, but fortunately I already ran accross this:

C1288:
Circuit Description
The Steering Wheel Position Sensor provides the EBCM with an analog voltage reading from 0.2 - 4.8 V depending on the steering wheel angle. The EBCM uses the analog voltage for the centering routine. The EBCM runs a centering routine when the vehicle speed goes above 10 km/h (6 mph) . When the vehicle reaches 10 km/h (6 mph) , the EBCM monitors the Steering Wheel Position Sensor inputs (Phase A, Phase B and Analog voltage) to see if the steering wheel is moving. If the steering wheel is not moving for a set period of time then the EBCM assumes the vehicle is going in a straight line. At this point, the EBCM looks at the analog voltage signal and reads the voltage. This voltage, normally around 2.5 V, is then considered the center position and the digital degrees also become zero at the same time. This centering routine is necessary to compensate for wear in the steering and suspension. Wear in the steering and suspension can result in a change in the relationship between the steering wheel and the front wheels. By running the centering routine, the EBCM can compensate for these changes by changing the digital and analog center position.

Conditions for Setting the DTC
The Steering Wheel Position Sensor analog output voltages falls outside 0.2 - 4.8 V range.

Action Taken When the DTC Sets
ABS and TCS remain enabled, Active Handling(TM) is disabled.


Indicators that turn on: Car Icon (TCS indicator)
Messages displayed on the DTC: Service Active HNDLG
Service Vehicle Soon

Diagnostic Aids
The following are possible causes:


A Steering Wheel Position Sensor circuit open.
A Steering Wheel Position Sensor shorted. Perform an inspection of the wiring and of the connectors. Failure to carefully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis causes part replacement with reappearance of the malfunction.
Test Description
The numbers below refer to step numbers on the diagnostic table.


Checks for a short to voltage.
Checks for a short to ground.
Checks for an open.

CySevans

DTC C1287 or C1288
Circuit Description
The vehicle stability enhancement system (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 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.

CySevans

Also found out there's a TSB on this:

Re: TSB #01-05-25-004 (WP) 7:06 PM 6/28/2002

Yellow: Traction Control/Handling Lamp On, Drivers Info Center Displays Service Active Hndlg (Handling) (Repair/Reprogram ABS Module) #01-05-25-004
Yellow: Traction Control/Handling Lamp On and Driver's Info Center Displays Service Active Hndlg (Handling) (Repair/Reprogram ABS Module)
2001 Chevrolet Corvette
Condition
Some customers may comment that the "Yellow" message, "Service Traction Active Handling", is illuminated on the Driver's Information Center.
The technician may find chassis DTC C1288 -- Vehicle Stability Enhancement System (VSES) Steering Wheel Sensor Phase A and B. When this code is set, the VSES is turned off; ABS and TCS remain operational.
Correction
Verify the Techline equipment has been updated with TIS software 20.5 or newer. If it has not been updated, do so now. This software was broadcast to dealerships on January 1, 2001. CD #1 for 2001 was mailed in early January, 2001.
Install the scan tool to the vehicle.
Enter the chassis applications.
Select F1: ABS/TCS/VSES.
Select F4: ID Information.
Select F1: Controller Information 2.
If the DE Calibration P/N is 12212175 (this calibration went into production 11/30/00 after VIN 15114788), refer to the Service Information for diagnosis.
If the DE Calibration P/N is 12204887, it will be necessary to update the ABS module.
Important
The update cannot be performed until fuse #25 (Body Control Module-Ignition 1, Instrument Panel Control) 10 amp is removed from the Instrument Panel fuse block which is located on the passenger's side of the vehicle (under the Instrument Panel and under the toe board).
Without removal of the fuse (prior to requesting information), unsuccessful reprogramming may occur.

Power down the scan tool.
Turn OFF the ignition and remove the key.
Remove fuse #25, (Body Control Module-Ignition 1, Instrument Panel Control) 10 amp.
Using the scan tool, perform the usual SPS reprogramming of the ABS module.
Power down the scan tool.
Turn OFF the ignition and remove the key.
Replace fuse #25, (Body Control Module-Ignition 1, Instrument Panel Control) 10 amp.
Verify the ABS DE Calibration P/N. If it is not P/N 12212175, redo the SPS programing procedure listed above.
Clear the codes from all the modules.
Warranty Information
For vehicles repaired under warranty, use.
Labor Operation
Description
Labor Time

N8520*
ABS Module - Reprogram
0.6 hr

*This is a unique labor operation to be used only with this bulletin. It will not be published in the Labor Time Guide.
ms.

CySevans

Above information courtesy of Corvette Forum. Gotta love search features.

CAM 00SS

So it's a software/programming upgrade?

Did ya get her fixed up?

CySevans

Well, the current working theory is that the vibration in the front caused by warped rotors is throwing off the steering wheel sensor and causing it to set the code. So, I am having her get the brakes fixed by one of her mechanic friends. Once the vibration is gone, I'll reset the code. If it stays gone, there's the answer.

But, yes, it's also possible that this TSB is in the loop as well. Could also be corroded grounds making poor contact. Something that these Vettes apparently have a problem with in moist, tropical environments. Thus, study all of this carefully because you may have to deal with it at some point, too.

CAM 00SS

I hear ya.

Right now the only trouble we have with the Vette is traction, or lack thereof. I would like to replace the run-flats before they are completely worn out.

I know Nitto makes tires for 18 inch rims, but I have been unsuccessful at finding the drag radials. The BF Goodrich G-force T/A's look pretty meaty, as do the Nitto NT555's. Any suggestions?

<EDIT> Okay, I found the drag radials, they just don't offer them in the exact size that comes stock on the Corvette. The closest I can get it P285/35 ZR 18's. They are just over 100 dollars cheaper than the OE run flats per each.

IRace2ChevyII

Plans for tonight?

CySevans

Oh, gosh. Forgot to call you.

Saturday?

Cinda is booked tonight (gym), I'm booked tomorrow night and possibly Thursday night (poker) and Friday night (pool).

Oh, what a tangled web we weave.

CySevans

It had nothing to do with the brakes or the alignment. There's definitely an electrical problem either with the sensors or the grounds.

She has it being worked on by a "friend" who is apparently a good mechanic, but doesn't appear to be too electrical system savvy because she said he pulled the steering wheel to look at the sensor without following the troubleshooting procedures to ohm it out or check the grounds. Well, it's her car and she can do with it as she pleases.

CySevans

I convinced my mother-in-law to let me have the car this morning (I let her drive the Z06) because the guy monkeyed with it all week and was about to throw anywhere between $65 and $900 worth of parts at it. He never checked the sensor (didn't ohm it out - I doubt he even knows what this means), and never checked the firmware. He did at least look at the grounds and determine they were okay (at least he says he did). Alignment was fine. Brakes are done (at least he got that right).

First thing this morning, I took it to the dealer and had them check the sensor and run the diags again. Didn't find any problems with the sensor, and could not repro the actual failure while connected to the computer. I told them to check the TSB that referred to C1288 error code on the '01 and '02 model years. They couldn't find anything on it. I pulled up the TSB on CorvetteForum in the Service Manager's office, and he pulled it up in the GM database. There was also a code C1287 set in the history on the car that wasn't there when I looked at it, so at first the mechanic was reluctant to do anything. I asked him to please at least check the software revision on the Steering Sensor Calibration and update it if it's the older version so at least we can rule that out. He did. Cost me $95 (primarily for diagnostic fees). Problem solved - haven't seen the error since, and I've been driving it most of the day.

Needless to say, I would have been real upset if this guy "friend" threw $1000 in parts + labor at this problem only to find out that it would not have made any difference. I'll recommend to my mother-in-law that she just have him do simple mechanical work and leave the high-tech stuff to me.

CySevans

Oh, Chris, as far as tire suggestions, I am running the Toyo Proxes T1-S tires. They don't get near the traction that the Nittos did, nor do they get as much dry traction as the F1 Supercar OEM tires. The Toyo's were the only decent tire I could find that had the OEM sizes for the Z06, and they cost me half as much as the Supercar tires. The coupe is a different story, though. Not sure where you can get tires for that. Too bad Nitto doesn't make the 555R-II's in the Vette sizes (or do they?). That would make for some great performance to have those all around like I had on the Trans Am. It would be a shame to put straight drag radials on the Vette and lose cornering performance.

boos2

Hey Vince, Chris if your want DR's BFG makes a DR in Vette size. Well your vette size Chris. Vince's tires are bigger. I put on some Kuhmos before I sold my vette, they were a great tire for the money. Non -run flat though but the do make a run-flat version. Nittos 18" DR is for the Lightning.

Vince, I was going to suggest taking the car to Jayson at MTI. He was VERY helpful when I was have electrical problems with my vette and he didn't charge me anything unless I actually needed a part. All the diagnosing and scanning, etc he did all for free. That is one reason I will be loyal to MTI when I get another vette.

Mike

CySevans

Well, it wasn't my Vette, and the type of software update it needed could only be provided by the dealership, so I was stuck anyway you look at it.

Yes, Jason was very helpful when I had MTI programming on the Trans Am. I will definitely use him and MTI in the future. Right now, I am very content with the Z06 in its stock form. It does everything I want it to do (except hook-up with the street tires ).