GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Express 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 DTC P0730

DTC P0730 Gas

Circuit Description

The powertrain control module (PCM) calculates the gear ratio based on the automatic transmission input shaft speed sensor (AT ISS) and the automatic transmission output shaft speed sensor (AT OSS) readings. The PCM compares the known transmission gear ratio to the calculated ratio for the selected gear ranges. Refer to Range Reference .

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

Conditions for Running the DTC

The engine is running longer than 7 seconds.

    • The system voltage is 8-18 volts.
    • No MAP sensor DTCs P0106, P0107, or P0108.
    • No TP sensor DTCs P0121, P0122, or P0123.
    • No AT OSS DTCs P0502 or P0503.
    • No AT ISS DTCs P0716 or P0717.
    • No TFP manual valve position switch DTC P1810.
    • No 4WD low DTC P1875.
    • The vehicle speed is greater than 8 km/h (5 mph).
    • The TP angle is greater than 15 percent.
    • The TFT is greater than 20°C (68°F).
    • No gear range change for greater than 6.0 seconds.
    • The engine torque must be between 108 N·m (80 lb ft) and:
       - 4.3 L, 5.7 L: 542 N·m (400 lb ft)
       - 8.1 L: 881 N·m (650 lb ft)
    • The engine is running greater than 400 RPM for 7 seconds and not in fuel cutoff.

Conditions for Setting the DTC
    • The following conditions are met for 10 seconds.
    • The Gear Ratio is one of the following:
       - Greater than 2.51 or less than 2.44
       - Greater than 1.50 or less than 1.44
       - Greater than 1.03 or less than 0.97
       - Greater than 2.12 or less than 2.05

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.
    • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
    • 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 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
    • A false or incorrect AT OSS or AT ISS signal can set DTC P0730.
    • DTC P1870 detects an incorrect gear ratio in fourth gear with TCC applied.
    • Inspect for any improperly installed after-market equipment.
    • Sticking or contamination of shift valves may cause intermittent incorrect gear ratios.
    • Refer to the Shift Solenoid Valve State and Gear Ratio table.
    • DTC P0730 defaults to an elevated line pressure condition which may result in TCC partial apply. This may induce idle surge and engine stall.

Test Description

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

  1. This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch could set DTC P1810.

    2.

  2. This step tests for proper ratios in each commanded gear state.

DTC P0730

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls (4.3 L) or Diagnostic System Check - Engine Controls (5.0/5.7 L) or Diagnostic System Check - Engine Controls (8.1 L) in Engine Controls

2

Perform the Transmission Fluid Checking Procedure.

Refer to Transmission Fluid Check .

Is the procedure complete?

--

Go to Step 3

Go to Transmission Fluid Check

3

  1. Install a Scan Tool .
  2. Turn ON the ignition, with the engine OFF.

    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 DTC Failure Records.
  4. Clear the DTCs.
  5. Start the engine.
  6. Apply the parking brake, and select each transmission range: D1, D2, D3, D4, N, R, and P.

Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic .

Does the Scan Tool TFP switch A/B/C display match each selected gear range?

--

Go to Step 4

Go to DTC P1810

4

  1. Drive the vehicle in D3 with greater than 15% TP.
  2. Drive the vehicle above 7 mph for greater than 2 seconds in each specified gear range.
  3. Use the Scan Tool snapshot mode to record the transmission gear ratio for each commanded gear range: REVERSE, 1st, 2nd, and 3rd.

Are the commanded gear ratios within the values for each specified gear range?

Rev: 2.04-2.12

1st: 2.42-2.50

2nd: 1.44-1.50

3rd: 0.25-1.03

Go to Diagnostic Aids

Go to Step 5

5
  1. Connect the J 21867 pressure gauge to the transmission line pressure tap.
  2. Perform the Line Pressure Check Procedure.

    3. Refer to Line Pressure Check .

Is the line pressure within specifications for each selected gear range?

--

Go to Step 6

Go to Step 8

6
  1. Remove the transmission oil pan.

    2. Refer to Automatic Transmission Fluid and Filter Replacement .

  2. Inspect the oil pan and the fluid for contamination.

Was excessive contamination found?

--

Go to Transmission Overhaul in Transmission Unit Repair Manual

Go to Step 7

7

Inspect the transmission for the following conditions:

    • Sticking shift valves
    • Stuck apply pistons

Did you find and correct the condition?

--

Go to Step 10

Go to Transmission Overhaul in Transmission Unit Repair Manual

8

Is the system line pressure low only in the specific gear which indicated an incorrect gear ratio?

--

Go to Step 9

Go to Symptoms - Automatic Transmission

9

Inspect for fluid pressure loss in the following areas:

    • 1-2 SS valve seal
    • 2-3 SS valve seal
    • Valve body passages
    • Valve body gaskets
    • Band apply pistons and seals
    • Clutch apply pistons and seals

Did you find and correct the condition?

--

Go to Step 10

Go to Transmission Overhaul in Transmission Unit Repair Manual

10

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. • Key ON, the engine is running.
    • Drive the vehicle in REVERSE, 1st, 2nd, and 3rd gear.
    • The PCM must see a valid gear ratio range versus the commanded gear ratio.
  4. Select Specific DTC.
  5. Enter DTC P0730.

Has the test run and passed?

--

System OK

Go to Step 1

DTC P0730 Diesel

Circuit Description

The powertrain control module (PCM) calculates a ratio based on the automatic transmission input shaft speed (ISS) sensor and output shaft speed (OSS) sensor readings. The PCM compares the known transmission gear ratio to the calculated ratio, for the selected gear range.

If the PCM detects an incorrect gear ratio, then DTC P0730 sets. DTC P0730 is a type C DTC.

Conditions for Running the DTC
    • No MAP DTCs P0106, P0107, P0108.
    • No AT ISS sensor DTCs P0716 or P0717.
    • No AT OSS sensor DTCs P0722 or P0723.
    • No TFP manual valve position switch DTC P1810.
    • The vehicle speed is greater than 6.4 km/h (5 mph).
    • The APP angle is greater than 25 percent.
    • The TFT is greater than 20°C (68°F).
    • System voltage is 8-18 volts.
    • 10 seconds must have elapsed since the last gear range change.
    • The engine speed is greater than 475 RPM for at least 7 seconds.
    • The engine speed is less than 3,750 RPM.
    • The engine torque is 100-642 N·m (80-475 lb ft).

Conditions for Setting the DTC
    • All of the Conditions for Running the DTC are met for 7 seconds.
    • The Gear Ratio is one of the following:
       - Greater than 2.52 or less than 2.42
       - Greater than 1.50 or less than 1.45
       - Greater than 1.02 or less than 0.98
       - Greater than 0.77 or less than 0.73
       - Greater than 2.12 or less than 2.04

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.
    • 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 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
    • First, diagnose and clear any engine DTCs that are present. Then inspect for any transmission DTCs that may have reset. If a DTC P0717 and a DTC P0730 are both present, diagnose DTC P0717 first.
    • Sticking or contaminated shift valves may cause an undefined gear ratio.
    • Refer to the Shift Solenoid Valve State and Gear Ratio table and the Range Reference table.
    • DTC P1870 detects an incorrect gear ratio in fourth gear with TCC applied.
    • DTC P0730 defaults to an elevated line pressure condition which may result in TCC partial apply. This may induce idle surge and engine stall.

Test Description

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

  1. This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch could set DTC P0730.

    2.

  2. This step tests for proper ratios in each commanded gear state.

P0730

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls

2

Perform the Transmission Fluid Checking Procedure.

Refer to Transmission Fluid Check .

Is the Transmission Fluid Checking Procedure complete?

--

Go to Step 3

Go to Transmission Fluid Check

3

  1. Install a Scan Tool .
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Before clearing the DTC, 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 Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Start the engine.
  6. Apply the parking brake, and select each transmission range: D1, D2, D3, D4, N, R, and P.

    7. Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic .

Does the Scan Tool TFP Switch A/B/C display match each selected gear range?

--

Go to Step 4

Go to DTC P1810

4

  1. Drive the vehicle in REVERSE and D4.
  2. Hold the vehicle speed above 8 km/h (65 mph) for greater than 2 seconds in the specified gear range.
  3. Use the Scan Tool snapshot mode in order to record the transmission gear ratio for each commanded gear range: REVERSE, 1st, 2nd, 3rd and 4th.

Are the gear ratios within the parameters for each specified gear range?

Rev: 2.04-2.12

1st: 2.42-2.52

2nd: 1.45-1.50

3rd: 0.98-1.02

4th: 0.73-0.77

Go to Diagnostic Aids

Go to Step 5

5
  1. Connect the J 21867 pressure gauge to the transmission line pressure tap.
  2. Perform the Line Pressure Check Procedure.

    3. Refer to Line Pressure Check .

Is the line pressure within specifications for each selected gear range?

--

Go to Step 6

Go to Step 8

6
  1. Remove the transmission oil pan.

    2. Refer to Automatic Transmission Fluid and Filter Replacement .

  2. Inspect the oil pan and the fluid for contamination.

Was excessive contamination found?

--

Go to Transmission Overhaul in Transmission Unit Repair Manual

Go to Step 7

7

Inspect the transmission for the following conditions:

    • Sticking shift valves
    • Stuck apply pistons

Was the condition found?

--

Go to Step 10

Go to Transmission Overhaul in Transmission Unit Repair Manual

8

Is the system line pressure low only in the specific gear which indicated an incorrect gear ratio?

--

Go to Step 9

Go to Symptoms - Automatic Transmission

9

Inspect for fluid pressure loss in the following areas:

    • 1-2 SS valve seal
    • 2-3 SS valve seal
    • Valve body passages
    • Valve body gaskets
    • Band apply pistons and seals
    • Clutch apply pistons and seals

Was the condition found?

--

Go to Step 10

Go to Transmission Overhaul in Transmission Unit Repair Manual

10
  1. Change the AT fluid and filter.
  2. Inspect for correct transmission fluid level.

    3. Refer to Transmission Fluid Check .

  3. Add new AT fluid as necessary.

    4. Important: The Clear TAPS function will clear all adapt cells. This may affect transmission performance. The PCM will update the transmission adapt cell values as the vehicle is driven.

  4. Using the Scan Tool , perform the Clear TAPS function.

Did you complete the above procedure?

--

Go to Step 11

--

11

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. • Start the engine.
    • Drive the vehicle in REVERSE, 1st, 2nd, 3rd and 4th gear.
    • The PCM must see a valid gear ratio versus the commanded gear ratio for 7 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0730.

Has the test run and passed?

--

System OK

Go to Step 1