Code
P1571
SATURN
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 the TCS/ABS/ESC module or actuator
- Blown fuse or faulty relay supplying the TCS/ESC/ABS module
- Faulty TCS/ESC/ABS module (internal driver failure)
- Faulty actuator (pump motor, solenoid) that loads the circuit abnormally
- Poor chassis or module ground
Symptoms
- Traction Control/ESC warning lamp illuminated
- Traction control disabled (no TCS intervention)
- Possible ABS/TCS warning lamps if systems share components
- Loss of traction control or limited stability control function
- No audible pump or solenoid operation when system would normally activate
What to check
- Retrieve freeze frame and read all stored codes with a scan tool; note any ABS/TCS or communication codes
- Visually inspect wiring, connectors, and pins for corrosion, damage, or looseness at the TCS/ABS/ESC module and actuator
- Check fuses and relays related to ABS/TCS/ESC for continuity and correct operation
- Backprobe the PWM circuit at the module with the connector connected and engine/vehicle in the state required to command TCS (use appropriate safety procedures)
- Use an oscilloscope to look for a PWM square wave on the circuit while commanding TCS or performing a road test (or simulated request)
- Check module power and ground circuits for proper voltage and resistance to ground
Signal parameters
- Typical PWM output: square wave referenced to chassis ground; amplitude ~0–battery voltage (0–12V)
- Typical expected PWM frequency: commonly between 50–200 Hz (varies by vehicle); duty cycle varies 0–100% depending on commanded output
- When system is idle/disabled expect 0 Hz (no frequency); when commanded expect a steady PWM waveform—use manufacturer spec if available
Diagnostic algorithm
- Connect a professional scan tool. Record P1571 and any related ABS/TCS codes and freeze frame data.
- Inspect visually: fuses, relays, module and actuator connectors, wiring harness for damage or corrosion. Repair obvious problems.
- Verify module power and ground with a multimeter. Repair poor power/ground before further testing.
- Backprobe the PWM output at the module connector. With a scope (preferred) or logic probe, command TCS (or perform specified procedure) and observe for a PWM waveform. Note frequency and duty cycle.
- If no PWM at the module output: check for related input signals and communication to the module (CAN) and repair as needed. If module receives correct inputs but produces no output, suspect module internal driver failure—consult manufacturer service info for pin-level tests.
- If PWM is present at module but absent at actuator connector: test continuity of the PWM conductor to the actuator, check for short to ground or battery, and inspect connectors. Repair wiring as needed.
- If wiring and actuator test good but system still faults, substitute/repair the TCS/ABS/ESC module per service procedures.
- Clear codes and verify repair by performing test drive and re-scanning for reoccurrence.
Likely causes
- Damaged connector or corroded pins at the TCS/ABS module
- Open or short in the PWM output conductor between module and actuator
- Faulty module output driver (module failure)
- Blown fuse or failed power/ground to the module
Fault status
Status
TCS PWM circuit frequency not detected. Traction control functionality may be disabled until the circuit and module are repaired.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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