Circuit Description
The powertrain control module (PCM) calculates the gear ratio based on the automatic transmission input shaft speed sensor (AT ISS) and output shaft speed sensor (AT OSS) input. 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
| • | No MAP sensor DTCs P0106, P0107, or P0108. |
| • | No TP sensor DTCs P0121, P0122, or P0123. |
| • | No AT OSS DTCs P0502 or P0503. |
| • | No ISS DTCs P0716 or P0717. |
| • | No TFP manual valve position switch DTC P1810. |
| • | No 4WD low DTC P1875. |
| • | The system voltage is 8-18 volts. |
| • | The vehicle speed is greater than 8 km/h (5 mph). |
| • | The throttle angle is greater than 15 percent. |
| • | The TFT is greater than 20°C (68°F). |
| • | No gear range change for greater than 6 seconds. |
| • | The engine torque must be between 108 N·m (80 lb ft) and: |
| - | 6.0L: 542 N·m (400 lb ft) |
| - | 8.1L: 881 N·m (650 lb ft) |
| • | The engine is running greater than 7 seconds. |
| • | The transfer ratio is 0.95-1.05. |
Conditions for Setting the DTC
The following gear ratios are met for 10 seconds:
| • | 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 aftermarket equipment. |
| • | Sticking or contamination of shift valves may cause intermittent incorrect gear ratios. |
| • | Refer to Shift Solenoid Valve State and Gear Ratio . |
| • | DTC P0730 defaults to an elevated line pressure which may result in partial TCC apply. This may produce an idle surge that could stall the engine. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch could set DTC P1810.
-
This step tests for proper ratios in each commanded gear state.
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 - 6.0L or Diagnostic System Check - Engine Controls in Engine Controls - 8.1L | ||||||||||||
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Did you perform the Transmission Fluid Checking Procedure? | -- | Go to Step 3 | Go to Transmission Fluid Check | ||||||||||||
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. 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 | |||||||||||||
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 |
Refer to the Line Pressure Check . Is the line pressure within specifications for each selected gear range? | -- | Go to Step 6 | Go to Step 8 | ||||||||||||
6 |
Refer to Automatic Transmission Fluid and Filter Replacement . 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:
Did you find and correct the condition? | -- | Go to Step 10 | Go to Transmission Overhaul in Transmission Unit Repair Manual | ||||||||||||
8 | Is low line pressure indicated for the specific gear that displayed incorrect gear ratio? | -- | Go to Step 9 | |||||||||||||
9 | Inspect for fluid pressure loss in the following areas:
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:
Has the test run and passed? | -- | System OK | Go to Step 1 |
