DTC P1571 Traction Control Torque Request Circuit. Buick Century 1997

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1997 🢒 Century 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P1571 Traction Control Torque Request Circuit

Engine Controls Components
Gen Control, Volts Lamp, Shift Select Switch, EBTCM Module
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The traction control system uses the antilock brake system in conjunction with the 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 spark timing.

•	Altering air/fuel ratio.

•	Altering boost PWM (VIN 1).

•	Shutting OFF up to three 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 Electronic Brake and Traction Control Module (EBTCM) 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 traction control not active, Desired Torque should vary between 99% and 100%. The Desired Torque display on the scan tool is not the PWM duty cycle.

Conditions for Setting the DTC

Desired torque signal PWM duty cycle is less than 5% or greater than 95%.
The conditions exists for up to 10 seconds

Action Taken When the DTC Sets

•	The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

•	The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

•	A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

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

•	Poor Connection or Damaged Harness.

Inspect PCM harness for an open or short to ground in the desired torque PWM circuit, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

•	Intermittent Test

Using a scan tool, observe Desired Torque display while moving 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 Fail 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	Value(s)	Yes	No
1	Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to the Powertrain On Board Diagnostic (OBD) System Check
2	Turn ON the ignition switch. Observe (Traction Control) Desired Torque display on the scan tool. Is (Traction Control) Desired Torque at or near the specified value?	100%	Go to Step 4	Go to Step 3
3	Turn OFF the ignition switch. Disconnect the Electronic Brake and Traction Control Module (EBTCM). Turn ON the ignition switch. Using a J 39200 Digital Multimeter, measure voltage between the TCS Desired Torque circuit at the EBTCM harness connector and ground. Does voltage measure the specified value?	5V	Go to Step 4	Go to Step 6
4	Turn OFF the ignition switch. Connect J 39700-25 ABS/TCS Pinout Box and Adapter to the EBTCM and to the EBTCM harness connector. Connect the digital multimeter to measure AC frequency between the TCS Desired Torque circuit and ground. Turn ON the ignition switch. Observe frequency on the digital multimeter. Is frequency between the specified values?	120 -135 Hz	Go to Step 5	Go to Step 7
5	Set the digital multimeter to % duty cycle. Connect the digital multimeter to measure duty cycle between the TCS Desired Torque circuit and ground. Turn ON the ignition switch. Observe duty cycle on the digital multimeter. Is duty cycle between the specified values?	5-95%	Go to Step 9	Go to Step 7
6	Turn OFF the ignition switch. Disconnect the PCM. Turn ON the ignition switch. 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 Repair Procedures in Electrical Diagnosis. Was a problem found?	--	Go to Step 11	Go to Step 9
7	Check for a poor connection at the EBTCM. If a problem is found, repair as necessary. Refer to Repair Procedures in Electrical Diagnosis. Was a problem found?	--	Go to Step 11	Go to Step 8
8	Replace the EBTCM. Refer to On-Vehicle Service in ABS/TCS. Is action complete?	--	Go to Step 11	--
9	Check for a poor connection at the PCM. If a problem is found, repair as necessary. Refer to Repair Procedu in Electrical Diagnosis. Was a problem found?	--	Go to Step 11	Go Step 10
10	Replace the PCM. Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is action complete?	--	Go to Step 11	--
11	Clear DTCs. Turn ON the ignition switch. Observe (Traction Control) Desired Torque on the scan tool. Is (Traction Control) Desired Torque at or near the specified value?	100%	System OK	Go to Step 2