P0730

Diagnostic Chart:

Description:

Circuit Description

The Powertrain Control Module (PCM) calculates gear ratio based on the transmission input and output speeds. The PCM compares the known transmission gear ratio to the calculated ratio for the selected gear range.

When the PCM detects an unknown transmission gear ratio, then DTC P0730 sets. DTC P0730 is a type D DTC.

Conditions for Setting the DTC

^ No Vehicle Speed (VSS) sensor DTCs P0502 or P0503.

^ No Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) DTC P1810

^ No Input Speed Sensor DTCs P0716 or P0717

^ No Throttle position (TP) Sensor DTCs P0121, P0122, or P0123

^ The engine is running.

^ The TFP Val. Position Sw. is not indicating Park or Neutral.

^ The TP is greater than 15%.

^ The vehicle speed is greater than 16 km/h (10 mph).

^ The transmission fluid temperature is greater than -10°C (14°F).

^ The MAP is greater than 20 kPa.

^ Engine torque is greater than 25N.m (20 lb. ft.).

^ The last manual range change was at least 3 seconds ago.

And one of the following conditions occurs:

^ The gear ratio is less than 1:2.87, or greater than 1:3.13, for 7 seconds.

^ The gear ratio is less than 1:1.54, or greater than 1:1.71, for 7 seconds.

^ The gear ratio is less than 1:0.91, or greater than 1:1.07, for 7 seconds.

^ The gear ratio is less than 1:0.61, or greater than 1:0.72, for 7 seconds.

^ The gear ratio is less than 1:2.02, or greater than 1:2.23, for 7 seconds.

Action Taken When the DTC Sets

^ The PCM commands maximum line pressure.

^ The PCM freezes shift adapts from being updated.

^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

^ DTC P0730 is stored in the PCM history.

Conditions for Clearing the DTC

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

Diagnostic Aids

^ Inspect for intermittent Automatic Transmission Input (Shaft) Speed Sensor (A/T ISS) circuit problems.

^ Inspect for intermittent Automatic Transmission Output (Shaft) Speed Sensor (A/T OSS) circuit problems.

^ Inspect for an incorrect calibration.

Test Description

The numbers below refer to the Step numbers on the diagnostic table.

3. This Step tests for low fluid level, which may cause slipping, and result in an undefined gear ratio.

4. This Step verifies that the correct gear ratios occur for commanded gears.

5. This Step tests for low line pressure.

7. When DTC P0730 sets, the PCM commands maximum line pressure and does not inhibit TCC engagement. This can lead to excessive heat build-up, causing the Torque Converter to "balloon." You must replace the Torque Converter.