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Makes 🢒 Chevrolet 🢒 1999 🢒 Malibu 🢒 Engine 🢒 Engine Controls - 3.1L (LG8) 🢒 DTC P0730 Incorrect Gear Ratio

DTC P0730 Incorrect Gear Ratio 2.4L

Circuit Description

The 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. Refer to Range Reference .

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

Conditions for Running the DTC
    • No TP DTCs P0121, P0122, or P0123.
    • No VSS DTCs P0502 or P0503.
    • No A/T ISS DTCs P0716 or P0717.
    • No TFP manual valve position switch DTC P1810.
    • The engine is running.
    • The TFP manual valve position switch is not indicating PARK or NEUTRAL.
    • The transmission fluid temperature is greater than 21°C (70°F).
    • The time since the gear select lever change is greater than 6 seconds.
    • The TP is greater than 15%.
    • The vehicle speed is greater than 8 km/h (5 mph).

Conditions for Setting the DTC

One of the following conditions occurs for 7 seconds:

    • The gear ratio is greater than 3.13:1.
    • The gear ratio is 2.23:1 to 2.87:1.
    • The gear ratio is 1.71:1 to 2.02:1.
    • The gear ratio is 1.07:1 to 1.54:1.
    • The gear ratio is 0.72:1 to 0.91:1.
    • The gear ratio is less than 0.61:1.

Action Taken When the DTC Sets
    • The PCM does not illuminate the malfunction indicator lamp (MIL).
    • The PCM commands maximum line pressure.
    • The PCM freezes shift adapts from being updated.
    • The PCM stores DTC P0730 in PCM history.

Conditions for Clearing the DTC
    • A scan tool clears the DTC from PCM history.
    • The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
    • The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch 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 conditions.
    • Inspect for intermittent automatic transmission output (shaft) speed sensor (A/T OSS) circuit conditions.
    • Inspect for an incorrect calibration.

Test Description

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

  1. This step tests for low fluid level, which may cause slipping, and result in an incorrect gear ratio.

    2.

  2. This step verifies that the correct gear ratios occur for commanded gears.

    3.

  3. This step tests for low line pressure.

DTC P0730 Incorrect Gear Ratio (2.4L)

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Visually inspect the transmission cooling system for fluid leaks.
  2. Repair leaks as necessary.

Refer to Fluid Leak Diagnosis .

Is the repair complete?

--

Go to Step 7

Go to Step 3

3

Was the Transmission Fluid Checking Procedure performed?

--

Go to Step 4

Go to Transmission Fluid Check

4

  1. Install the Scan Tool .
  2. Turn the ignition switch to the RUN position.

    3. Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

  3. Record the Failure Records.
  4. Clear the DTCs.
  5. Use the scan tool snapshot mode in order to record the transmission gear ratios.
  6. Drive the vehicle in transmission gear ranges 1, 2, 3 and D with the TP greater than 15%, and the vehicle speed greater than 8 km/h (5 mph).
  7. Record each transmission gear.

Did the commanded gear ratio match the specified ranges?

REVERSE: 2.02:1-2.23:1

1st: 2.87:1-3.13:1

2nd: 1.54:1-1.71:1

3rd: 0.91:1-1.07:1

4th: 0.61:1-0.72:1

Go to Diagnostic Aids

Go to Step 5

5

Perform the Line Pressure Check Procedure.

Refer to Line Pressure Check .

Is the line pressure within specifications?

--

Go to Step 7

Go to Step 6

6
  1. Inspect for excessive clutch wear.

    2. Refer to Clutch Plate Diagnosis .

  2. Repair as necessary.

Is the repair complete?

--

Go to Step 7

--

7

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • Drive the vehicle in D4 with the throttle greater than 15% in order to obtain any one of the following gear ratios for 7 seconds.
    • REVERSE: 2.02:1-2.23:1
    • 1st: 2.87:1-3.13:1
    • 2nd: 1.54:1-1.71:1
    • 3rd: 0.91:1-1.07:1
    • 4th: 0.61:1-0.72:1
  4. Select Specific DTC.
  5. Enter DTC P0730.

Has the test run and passed?

--

System OK

Go to Step 1

DTC P0730 Incorrect Gear Ratio 3.1L

Circuit Description

The 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. Refer to Range Reference .

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

Conditions for Running the DTC
    • No TP DTCs P0121, P0122 or P0123.
    • No VSS DTCs P0502 or P0503.
    • No A/T ISS DTCs P0716 or P0717.
    • No TFP manual valve position switch DTC P1810.
    • The engine is running.
    • The TFP manual valve position switch is not indicating PARK or NEUTRAL.
    • The transmission fluid temperature is greater than 21°C (70°F).
    • Engine torque is greater than 25 N·m (20 lb ft).
    • The time since the gear select lever change is greater than 6 seconds.
    • The TP is greater than 15%.
    • The vehicle speed is greater than 8 km/h (5 mph).

Conditions for Setting the DTC

One of the following conditions occurs for 7 seconds:

    • The gear ratio is greater than 3.13:1.
    • The gear ratio is 2.23:1 to 2.87:1.
    • The gear ratio is 1.71:1 to 2.02:1.
    • The gear ratio is 1.07:1 to 1.54:1.
    • The gear ratio is 0.72:1 to 0.91:1.
    • The gear ratio is less than 0.61:1.

Action Taken When the DTC Sets
    • The PCM does not illuminate the malfunction indicator lamp (MIL).
    • The PCM commands maximum line pressure.
    • The PCM freezes shift adapts from being updated.
    • The PCM stores DTC P0730 in PCM history.

Conditions for Clearing the DTC
    • A scan tool clears the DTC from PCM history.
    • The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
    • The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch 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 conditions.
    • Inspect for intermittent automatic transmission output (shaft) speed sensor (A/T OSS) circuit conditions.
    • Inspect for an incorrect calibration.

Test Description

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

  1. This step tests for low fluid level, which may cause slipping, and result in an incorrect gear ratio.

    2.

  2. This step verifies that the correct gear ratios occur for commanded gears.

    3.

  3. This step tests for low line pressure.

DTC P0730 Incorrect Gear Ratio (3.1L)

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Visually inspect the transmission cooling system for fluid leaks.
  2. Repair leaks as necessary.

Refer to Fluid Leak Diagnosis .

Is the repair complete?

--

Go to Step 7

Go to Step 3

3

Was the Transmission Fluid Checking Procedure performed?

--

Go to Step 4

Go to Transmission Fluid Check

4

  1. Install the Scan Tool
  2. Turn the ignition switch to the RUN position.

    3. Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

  3. Record the Failure Records.
  4. Clear the DTCs.
  5. Use the scan tool snapshot mode in order to record the transmission gear ratios.
  6. Drive the vehicle in transmission gear ranges 1, 2, 3 and D with the TP greater than 15%, and the vehicle speed greater than 8 km/h (5 mph).
  7. Record each transmission gear.

Did the commanded gear ratio match the specified ranges?

REVERSE: 2.02:1-2.23:1

1st: 2.87:1-3.13:1

2nd: 1.54:1-1.71:1

3rd: 0.91:1-1.07:1

4th: 0.61:1-0.72:1

Go to Diagnostic Aids

Go to Step 5

5

Perform the Line Pressure Check Procedure.

Refer to Line Pressure Check .

Is the line pressure within specifications?

--

Go to Step 7

Go to Step 6

6
  1. Inspect for excessive clutch wear.

    2. Refer to Clutch Plate Diagnosis .

  2. Repair as necessary.

    3. Refer to Unit Repair.

Is the repair complete?

--

Go to Step 7

--

7

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • Drive the vehicle in D4 with the throttle greater than 15% in order to obtain any one of the following gear ratios for 7 seconds.
    • REVERSE: 2.02:1-2.23:1
    • 1st: 2.87:1-3.13:1
    • 2nd: 1.54:1-1.71:1
    • 3rd: 0.91:1-1.07:1
    • 4th: 0.61:1-0.72:1
  4. Select Specific DTC.
  5. Enter DTC P0730.

Has the test run and passed?

--

System OK

Go to Step 1