DTC P1571 Traction Control Torque Request Circuit
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PostPosted: Fri Nov 12, 2004 12:56 pm    Post subject: DTC P1571 Traction Control Torque Request Circuit Reply with quote

DTC P1571 Traction Control Torque Request Circuit


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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 connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.
  • For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit . 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 systems.

For an intermittent condition, refer to Symptoms .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

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

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

DTC P1571 Desired Torque Circuit

Step

Action

Values

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.

  1. Install the scan tool.
  2. Turn OFF the ignition.
  3. Disconnect the EBTCM electrical connector. Refer to Electronic Brake Control Module (EBCM) Replacement in Antilock Brakes.
  4. Turn ON the ignition with the engine OFF.
  5. Probe the Desired Torque circuit at the EBTCM electrical connector with the DMM 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 with the DMM 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 with a test lamp connected to B+.

Is the test lamp illuminated?

--

Go to Step 8

Go to Step 6

6

  1. Test the Desired Torque circuit for an open. Refer to Testing for Continuity in Wiring Systems.
  2. 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

  1. Inspect for poor connections at the PCM. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
  2. 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.

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .

Is the action complete?

--

Go to Step 11

--

11

  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option with the scan tool.
  2. Start the engine and idle at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number with the scan tool.
  4. 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 with the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to applicable DTC

System OK

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