DTC P1571 Traction Control Torque Request Circuit. Pontiac Bonneville 2000

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2000 🢒 Bonneville 🢒 DTC 🢒 DTC P1571 Traction Control Torque Request Circuit

Engine Controls Components
OBD II Symbol Description Notice
EBCM, Generator, Engine Oil Level Switch
Handling ESD Sensitive Parts Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The traction control system uses the antilock brake system in conjunction with the powertrain control module (PCM) fuel and ignition controls to limit drive wheel slippage during acceleration. The PCM controlled portion of the traction control system reduces engine torque by any or all of the following methods:

•	Retarding the spark timing

•	Altering the air/fuel ratio

•	Altering the boost PWM (VIN 1)

•	Shutting OFF up to 3 injectors

To determine the amount of torque reduction required, the PCM monitors the TCS Desired Torque PWM signal from the electronic brake and traction control module (EBTCM). The PCM also provides a TCS delivered torque PWM informing the EBTCM of how much torque is being produced by the engine. The Desired Torque display on the scan tool indicates the amount of engine torque requested by the EBTCM. With the traction control inactive, the Desired Torque should vary between 99 and 100 percent . The Desired Torque display on the scan tool is not the PWM duty cycle.

Conditions for Running the DTC

The traction control is active.

Conditions for Setting the DTC

•	The desired torque signal PWM duty cycle is less than 5 percent or more than 95 percent .

•	The conditions exist for up to 10 seconds.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The history DTC clears after 40 malfunction free warm-up cycles.

•	The PCM receives a clear code command from the scan tool.

Diagnostic Aids

An intermittent may be caused by a faulty connection, rubbed through wire insulation, or a wire broken inside the insulation. Check for the following conditions:

•	A faulty connection or a damaged harness--Inspect the PCM harness for an open or a short to ground in the desired torque PWM circuit, improper mating, broken locks, improperly formed or damaged terminals, faulty terminal to wire connections, and damaged harnesses.

•	Using a scan tool, observe the Desired Torque display while moving the related connectors and wiring harness. If the failure is induced, the displayed value will change. This may help to isolate the location of the malfunction.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

DTC P1571 - TCS Desired Torque Circuit

Step	Action	Values	Yes	No
1	Was the Powertrain On Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Turn ON the ignition. Observe the traction control Desired Torque display on the scan tool. Is the Desired Torque approximately equal to the specified value?	100 percent	Go to Step 4	Go to Step 3
3	Turn OFF the ignition. Disconnect the electronic brake and traction control module (EBTCM). Turn ON the ignition, leaving the engine OFF. Use a digital multimeter (DMM) in order to measure the voltage between the TCS desired torque circuit and ground at the EBTCM harness connector. Does the voltage equal the specified value?	5 V	Go to Step 4	Go to Step 6
4	Turn OFF the ignition. Connect a J 39700 ABS/TCS pinout box and aJ 39700-300 adapter to the EBCM and to the EBCM harness connector. Use the DMM to measure the AC frequency between the TCS desired torque circuit and ground. Turn ON the ignition, leaving the engine OFF. Observe the frequency on the digital multimeter. Is the frequency within the specified range?	120-135 Hz	Go to Step 5	Go to Step 7
5	Set the DMM to percent duty cycle. Use the DMM to measure the duty cycle between the TCS desired torque circuit and ground. Turn ON the ignition, leaving the engine OFF. Observe the duty cycle on the digital multimeter. Is the duty cycle within the specified range?	5-95 percent	Go to Step 9	Go to Step 7
6	Turn OFF the ignition. Disconnect the PCM. Turn ON the ignition, leaving the engine OFF. Check the TCS desired torque circuit for an open, a short to ground, or a short to voltage. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems . Was a problem found?	--	Go to Step 11	Go to Step 9
7	Check for a faulty connection at the EBTCM. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems . Was a problem found?	--	Go to Step 11	Go to Step 8
8	Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Did you complete the repair?	--	Go to Step 11	--
9	Check for a faulty connection at the PCM. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems . Was a problem found?	--	Go to Step 11	Go Step 10
10	Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair?	--	Go to Step 11	--
11	Clear the DTCs. Turn ON the ignition switch. Observe the traction control Desired Torque on the scan tool. Does the Desired Torque approximately equal the specified value?	100 percent	System OK	Go to Step 2