Code
P0374
GWM
P — Powertrain
- No Timer A signal pulses
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in Timer A signal circuit
- Corroded or loose connector at sensor/actuator or ECM
- Failed Timer A device (timing actuator, VVT solenoid, or dedicated timing sensor)
- Failed camshaft/crankshaft position sensor affecting Timer A detection
- Blown fuse or faulty power/ground to the timing circuit
- Mechanical timing failure (broken timing chain/belt, jumped timing)
Symptoms
- Malfunction Indicator Lamp (MIL) on
- Engine may not start or is hard to start
- Rough idle, misfire, or running poorly
- Reduced engine power or limp-home mode
- Erratic or no cam timing control (if VVT affected)
- Possible unusual engine noise if mechanical timing failed
What to check
- Read freeze frame data and full DTC list with a scan tool
- Verify vehicle battery voltage and cranking voltage
- Visual inspection of Timer A connector, wiring harness and ECM connector for damage/corrosion
- Check fuses and relays supplying the timing/actuator circuits
- Backprobe the Timer A signal terminal with a multimeter or oscilloscope while cranking/running
- Scan for related codes (cam/crank sensor, VVT solenoid, PCM communication)
Signal parameters
- Signal type: pulsed digital/square-wave from Timer A sensor or switched driver for timing actuator (depends on design)
- Voltage levels: typically 0–5 V logic or 0 V to battery voltage for switch-type outputs (verify vehicle-specific service data)
- Frequency: proportional to engine speed (cranking = lower frequency, rises with RPM); pulses per cam/crank revolution depend on sensor type
- Expected behavior: consistent pulses when cranking and during running; no long gaps or flat line
Diagnostic algorithm
- Verify DTC P0374 present and note freeze-frame data. Clear codes and attempt to re-create the fault to confirm repeatability.
- Check battery and charging system. Low voltage can cause missing signals—ensure good cranking voltage (>9.5 V) during tests.
- Visually inspect Timer A connector, wiring, and ECM connector. Repair any pin damage, corrosion, or loose terminals.
- Check related fuses/relays and supply/ground circuits for the Timer A sensor/actuator; repair as needed.
- Use a digital storage oscilloscope (preferred) or an appropriate multimeter to probe the Timer A signal while cranking and running. Look for absent signal, incorrect voltage levels, or intermittent pulses.
- Perform a wiggle test of the wiring and connectors while monitoring the signal to locate intermittent faults.
- If no signal at the PCM, trace continuity from the sensor/actuator to the PCM pin. Repair/open circuits or shorts to ground/battery.
- If wiring and power/ground are good but no signal, replace the Timer A sensor/actuator per manufacturer procedure and retest.
- If replacement of sensor/actuator does not restore pulses, verify mechanical timing (cam/crank alignment marks) to ensure timing chain/belt integrity.
- If mechanical timing is correct and all wiring/components test good, consult vehicle-specific service info for PCM tests, reflashing, or replacement as last resort.
Likely causes
- Damaged or disconnected wiring/connector to Timer A
- Failed Timer A actuator or sensor (electrical failure)
- Loss of mechanical timing (chain/belt jumped or broken)
- Insufficient power/ground to the circuit (fuse, relay, battery)
- PCM not detecting a good signal (rare)
Fault status
Status
PCM detected no pulse signal from the Timer A circuit. DTC P0374 stored. Engine control may be limited; diagnose wiring, sensor/actuator, power/ground, and mechanical timing to restore proper signal.
Repair difficulty: Medium
Diagnostic time: 1-4 hours
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