Code
P1571
OLDSMOBILE
P — Powertrain
TCS PWM Circuit No Frequency
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the TCS PWM circuit
- Corroded or loose connector at TCS module, PCM or actuator
- Failed TCS actuator/pump/solenoid (PWM-driven device)
- Faulty TCS or ABS control module
- Low or intermittent supply voltage (battery, fuse, ignition feed)
- Poor ground for the TCS/PCM
Symptoms
- TCS/Traction Control lamp illuminated or TCS disabled message
- Reduced traction control or loss of traction control function
- ABS warning may also be present
- Vehicle may not apply brake modulation or torque reduction during wheel slip
- No PWM frequency present when inducing slip (measured at actuator/command wire)
What to check
- Read and record all stored DTCs and freeze-frame data with a scan tool
- Verify battery voltage (12.4–12.9 V nominal) and check fuses/ignition feeds to TCS/ABS module
- Visually inspect wiring and connectors for damage, corrosion, bent pins or moisture
- Check for related codes (wheel speed sensors, module communications)
- Backprobe the PWM output connector and monitor for voltage/frequency while commanded (use oscilloscope or frequency-capable meter)
- Wiggle wiring while monitoring to look for intermittent faults
Signal parameters
- Expected: PWM signal present on TCS actuator command wire when TCS is active (approximate)
- Frequency: typically in the low Hz to low hundreds of Hz range (approx 2–200 Hz depending on model) — consult vehicle-specific data
- Duty cycle: varies from 0–100% depending on commanded apply
- Voltage amplitude: typically 0–12 V (module ground switching or open-drain style) — verify against vehicle wiring diagrams
Diagnostic algorithm
- Connect a professional scan tool, read all codes and data, record freeze-frame data and clear codes.
- Verify battery voltage and inspect fuses and power/ground to the TCS/ABS module; repair any low supply or open fuse.
- Visually inspect PWM output wiring, connectors and grounds for damage or corrosion; repair any faults.
- With the scan tool, command TCS function (or induce controlled wheel slip) while backprobing the PWM output at the module and at the actuator connector; observe with an oscilloscope or frequency-capable DMM for presence of PWM frequency.
- If no PWM at module output but wiring and supply/ground are good, suspect module fault. If PWM present at module but not at actuator, check continuity and resistance of actuator coil/solenoid; replace actuator if open/shorted or out-of-spec.
- Repair wiring or replace faulty connector/pins; re-test system and clear codes.
- If module replacement is required, follow vehicle-specific programming/relearn procedures before final verification.
- After repairs, road-test and re-scan to confirm P1571 does not return.
Likely causes
- Damaged harness or pinback at PWM output connector
- Failed PWM-driven solenoid/actuator (open coil or internal failure)
- Faulty TCS/ABS control module not generating PWM
- Blown fuse or poor power/ground to module
Fault status
Status
No frequency detected on the Traction Control System (TCS) PWM output circuit; traction control disabled until circuit is restored.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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