P0730

DIAGNOSTIC TROUBLE CODE (DTC) P0730 INCORRECT GEAR RATIO





Circuit Description
The Powertrain Control Module (PCM) calculates gear ratio based on the transmission input and Output Speed Sensor (OSS) readings. The PCM compares the known transmission gear ratio to calculated ratio for the particular gear range selected. When the PCM detects an unknown transmission gear ratio, then Diagnostic Trouble Code (DTC) P0730 sets.

Conditions For Setting The DTC
- No Vehicle Speed Sensor (VSS) DTCs P0722 or P0723.
- No Input Speed Sensor (ISS) DTCs P0716 or P0717.
- No Throttle Position (TP) Sensor codes.
- No Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) DTC P1810.
- Engine running.
- Time since last manual gear select lever change is greater than three seconds.
- Transmission not in P (Park) or N (Neutral).
- TP is greater than 12%.
- Manifold Absolute Pressure (MAP) is greater than 10 kPa.
- Vehicle speed is greater than 5 km/h (3 mph).
- Transmission temperature is greater than 20°C (68°F).
- And one of the following conditions occur:
- Gear ratio is greater than 3.13 for seven seconds.
- Gear ratio is less than 2.87 or greater than 2.23 for seven seconds.
- Gear ratio is less than 2.02 or greater than 1.71 for seven seconds.
- Gear ratio is less than 1.54 or greater than 1.07 for seven seconds.
- Gear ratio is less than 0.91 or greater than 0.72 for seven seconds.
- Gear ratio is less than 0.61 for seven seconds.

Action Taken When The DTC Sets
- PCM does not illuminate the Malfunction Indicator Lamp (MIL).
- PCM will command maximum line pressure.
- PCM will freeze shift adapts from being updated.
- PCM will flash the Power Light.
- DTC P0730 will be stored in PCM memory.

Conditions For Clearing The DTC
- Any one of the following occur:
- Gear ratio is between 2.87 - 3.13 for seven seconds.
- Gear ratio is between 1.54 - 1.71 for seven seconds.
- Gear ratio is between 0.91 - 1.07 for seven seconds.
- Gear ratio is between 0.61 - 0.72 for seven seconds.
- Gear ratio is between 2.02 - 2.23 for seven seconds.
- To cancel DTC fail actions, the fault must no longer exist and the ignition must be cycled off for five seconds.
- History DTCs can be cleared by using a Scan Tool.

Diagnostic Aids
- Check for intermittent Input Speed Sensor (ISS) or Output Speed Sensor (OSS) circuit problems.
- Check for possible incorrect calibration

Test Description
The numbers below refer to the step numbers on the diagnostic chart.
3. This step checks for possible low fluid level causing slipping resulting in an undefined gear ratio.
4. This step checks for correct gear ratios for commanded gears.
5. This step checks for low line pressure.





DTC P0730 - Incorrect Gear Ratio