P0730 - Incorrect Gear Ratio
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Incorrect Gear Ratio (P0730).
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Incorrect Gear Ratio – Coil Resistance | Resistance (Ω) | 3 - 30 Ω (typical) | Connector disconnected at 20°C |
| Incorrect Gear Ratio – Duty Cycle | PWM (%) | 5 - 95 % (modulates with target) | Engine running, actuator in control |
| Incorrect Gear Ratio – Supply Voltage | Voltage (V) | 11.8 - 14.4 V | Ignition ON at connector |
Connector disconnected at 20°C
Engine running, actuator in control
Ignition ON at connector
Oscilloscope Waveform Analysis
2 ms/div, 20 V/divPossible Causes
Chafed or pinched wiring harness along the signal path to Incorrect Gear Ratio
Internal mechanical wear or carbon deposits inside Incorrect Gear Ratio
Defective internal output driver or reference circuit in the control module for Incorrect Gear Ratio
Symptoms
4
Recommended Solution
Review freeze-frame environmental data and perform fundamental voltage-drop and resistance checks on the circuit.
Verify loaded supply voltage and harness terminal pins at Incorrect Gear Ratio.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Incorrect Gear Ratio.
Check supply and the low-side driver at the ECM connector. Replace the actuator or repair the circuit based on the readings.
Mechanic's Tip
Use the scan-tool output test with the scope on the control side at the same time. If duty changes but the actuator does not move, the valve is stuck — not the electrical fault you were chasing.