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Old 10-09-2011, 11:07 PM   #2
Bill Dearborn
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Member Since: Oct 1999
Location: Charlotte (formerly Endicott, NY) NC
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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 . 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 .


Bill
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