checked her codes today. not getting any service nothing lights or messages, just wanted to check the codes.

all history codes:

P0461
P1431
P1571

U1255

i think the first three were PCM codes and the last one was an IPC code i think, anyway, i reset them all, turned key off, restarrted car, checked em again and another P1571 history code just popped up, i think thats the one that for some reason these early cars just like to show but i cant remember for sure. thanks in advance

 

Here is a list of codes:

http://www.ae1m.com/c5codes.html

P0461 Fuel Level Sensor 1 Circuit Performance
P1431 Fuel Level Sensor 2 Circuit Performance
P1571 ASR Desired Torque

U1255 Serial Data Line Malfunction

 

DTC P1571 Traction Control Torque Request Circuit




Circuit Description
The PCM supplies 5 volts on the desired torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases, the PCM disables a number of fuel injectors. This diagnostic tests for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal, this DTC sets.

Conditions for Running the DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
Conditions for Setting the DTC
The desired torque signal is not received by the PCM for 3 seconds.

Action Taken When the DTC Sets
The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the MIL/DTC
A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL/DTC.
Diagnostic Aids

Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.
Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).

The following may cause an intermittent:
Poor connections; Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
Corrosion
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
For an intermittent condition, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

This step determines if the EBTCM is receiving the 5 volts from the PCM. Use the connector test kit adaptor J 35616-A when probing the EBTCM connector.

If no DTCs are set, inspect connections at the EBTCM.

DTC P1571 Desired Torque Circuit Step
Action
Value(s)
Yes
No

1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important
Perform this diagnostic procedure only if the customer's concern is related to the ABS and/or the Traction Control systems. Refer to Diagnostic System Check - ABS in Antilock Brakes System.


Install the scan tool.
Turn OFF the ignition.
Disconnect the EBTCM electrical connector.
Turn ON the ignition leaving the engine OFF.
Probe the Desired Torque circuit at the EBTCM electrical connector using the DMM J 39200 connected to ground.
Does the DMM display near the specified value?
5V
Go to Step 3
Go to Step 4

3

Important
Verify communication between the scan tool and the EBTCM before you continue with this diagnostic. Refer to Diagnostic System Check - ABS in Antilock Brakes System.


Are any ABS/TCS/BCM DTCs set?
--
Go to Diagnostic System Check - Body Control System in Body Control Systems or Diagnostic System Check - ABS in Antilock Brake System
Go to Diagnostic Aids

4
Probe the Desired Torque circuit at the EBTCM electrical connector using the DMM J 39200 connected to ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the DMM display near the specified value?
B+
Go to Step 7
Go to Step 5

5
Probe the Desired Torque circuit at the EBTCM electrical connector using a test lamp connected to B+.

Is the test lamp illuminated?
--
Go to Step 8
Go to Step 6

6
Test the Desired Torque circuit for an open. Refer to Testing for Continuity in Wiring Systems.
If you find an open circuit, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 9

7
Repair the short to B+ on the Desired Torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 11
--

8
Repair the short to ground on the Desired Torque circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?
--
Go to Step 11
--

9
Inspect for poor connections at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If you find a poor connection, repair the terminal as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 10

10

Important:
Program the replacement PCM. Refer to PCM/TAC Module Replacement .


Replace the PCM.

Is the action complete?
--
Go to Step 11
--

11
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
Idle the engine at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate vehicle within the Conditions for Running this DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test failed?
--
Go to Step 2
Go to Step 12

12
Select the Capture Info option and the Review Info option using the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?
--
Go to applicable DTC
System OK

 

Before you get too deep in to troubleshooting these issues, there are a couple of things that you can check. C5's are known to have ground issues. The older your car is the more likley you are to expierence problems with corrosion.
My 98 had some serious electrical problems and just cleaning the grounds solved 90% of them.

Your fuel system problems can very well be ground related! The ground point for that circuit is located on the drivers side frame rail, just aft of the rear wheel. If you look in betweem the wheel and the inner fender well you should see it. It will be an eyelet type ground. make sure that you soak the stud and nut in WD-40 or PB Blaster and wire brush the stud and nut prior to removal. If it wrings off i have a solution for that too!

Here are a few pics:


Woops,,just noticed something! The picture shows that the ground lug is attached with a screw vise a stud and a nut. My stud broke off and I reconnected it using a self tapping sheet metal screw. works like a champ!!!

Clean the eyelet and area on the frame where it contacts. It needs to be very clean. The other thing that can cause the fuel sys code is a dirty fuel sender. Run some red line or Chevron Techron fuel sys cleaner in a couple of tanks if the ground cleaning does not correct the issue. The ground on the other side of the frame in the exact same position is for your EBTCM! Clean that one too!

Here is a post on how to clean ALL the other types of grounds on the car. Doing this maintenance has helped numerous other forum members and saved them many dollars!

http://forums.corvetteforum.com/show...al+information

If you have any questions about this topic, PLEASE let me know.

Bill Curlee