Code
P1194
PLYMOUTH
P — Powertrain
Incorrect Or Irrational Performance Has Been Detected For The PWM
AI status
Completed
Completed
100%
Causes
- Damaged or corroded wiring or connector at the controlled actuator
- Short to battery or ground in the PWM circuit
- High circuit resistance or intermittent open
- Failed or sticking PWM-driven actuator (IAC valve, purge/EVAP solenoid, VVT/solenoid, fuel pump control module, etc.)
- Faulty ECM/PCM or driver transistor
- Poor or missing ground or supply voltage to the circuit
Symptoms
- Malfunction indicator lamp (MIL/CEL) illuminated
- Erratic idle, stalling, rough running or surging
- Actuator not responding or behaving unpredictably
- Reduced performance or limp-home mode (depending on affected circuit)
- Related systems (fuel, EVAP, VVT, idle control) operating abnormally
What to check
- Read freeze frame and all stored codes; note related codes and conditions
- Perform visual inspection of wiring, connectors and grounds for damage, corrosion or looseness
- Backprobe connector and compare commanded vs actual duty cycle with scanner or oscilloscope
- Check supply voltage and ground at actuator connector with key on and engine running
- Wiggle harness while observing live data to reproduce fault
- Measure resistance of actuator (where applicable) and compare to specification
Signal parameters
- Duty cycle range: 0% to 100% (commanded vs actual should track)
- Typical PWM frequency: commonly 20 Hz to several hundred Hz depending on actuator (consult service data)
- Voltage amplitude: pulses generally swing between ground and supply (0 V to ~5–12 V depending on circuit)
- Use an oscilloscope to verify clean square waveform, correct frequency and proportional duty
- ECM command and actuator response should correlate in live data (commanded duty vs measured)
Diagnostic algorithm
- Capture freeze frame and live data, note which actuator/circuit is reported and operating conditions when fault set.
- Clear codes and attempt to re-create. If intermittent, perform wiggle test and drive cycle while monitoring live duty readings.
- Visually inspect the harness, connector and ground for the reported circuit; repair any damage.
- Backprobe the actuator connector. With a scan tool or multimeter/scope, compare commanded duty to actual measured signal at the actuator.
- Check supply voltage and ground integrity at the connector. Repair poor grounds or low supply voltage before further testing.
- If the measured PWM does not match command at the actuator but the ECM is commanding correctly, suspect wiring/connector between ECM and actuator. Repair or replace as needed.
- If wiring checks good but actuator does not respond correctly, bench-test or temporarily substitute a known-good actuator (if feasible) to confirm component failure.
- If actuator and wiring test good but PWM is still irrational at the ECM output, suspect ECM driver failure — confirm with scope and consult manufacturer technical service information before replacing ECM.
- After repairs, clear codes and perform functional/road test to verify the fault does not return.
Likely causes
- Open or intermittent harness between ECM and actuator
- Connector corrosion or bent pins causing intermittent contacts
- Actuator internal failure causing unexpected duty response
- Shorted output transistor inside ECM
- Low battery or unstable supply voltage affecting PWM performance
Fault status
Status
ECM detected PWM control signal behavior outside expected parameters (incorrect/irrational duty, frequency or waveform). Fault stored and MIL may be set.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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