Circuit Description
The PCM calculates the gear ratio based on data from the automatic transmission input shaft speed (A/T ISS) sensor and the vehicle speed sensor (VSS). The PCM compares the known transmission gear ratio to a calculated ratio for each gear range selected. The VSS output is translated to RPM and mph by the PCM for various uses.
If the PCM detects an incorrect gear ratio because of excessive slip within the transmission, then DTC P0730 sets. DTC P0730 is a type C DTC.
Conditions for Running the DTC
| • | No TP sensor DTCs P0121, P0122 or P0123 are set. |
| • | No VSS DTC P0502 or P0503 is set. |
| • | No A/T ISS sensor DTC P0716 or P0717 is set. |
| • | No TFP manual valve position switch DTC P1810 is set. |
| • | The engine speed is greater than 500 RPM for 5 seconds and not in fuel shut off. |
| • | The transmission is not in PARK or NEUTRAL. |
| • | The TP angle is greater than 14%. |
| • | The vehicle speed is greater than 11 km/h (7 mph). |
| • | The transmission fluid temperature is greater than 20°C (68°F). |
| • | The engine torque is 70-270 N·m (50-200 lb ft). |
| • | The time since the last gear range change is greater than 3 seconds. |
Conditions for Setting the DTC
DTC P0730 sets when one of the following conditions occurs for 7 seconds:
| • | The gear ratio is more than 2.97:1. |
| • | The gear ratio is 2.43:1 to 2.87:1. |
| • | The gear ratio is 1.62:1 to 2.33:1. |
| • | The gear ratio is 1.05:1 to 1.52:1. |
| • | The gear ratio is 0.75:1 to 0.95:1. |
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. |
| • | 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 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 the connectors at the controller, the component and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Wiring Systems. |
| • | Ask the customer about vehicle overloading, exceeding the trailer towing limit or towing in overdrive. |
| • | Refer to Range Reference . |
| • | Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Intermittent Conditions in Engine Controls - 3.8L. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for low fluid level, which may cause slipping and result in an undefined gear ratio.
-
This step verifies that the correct gear ratios occur for commanded gears.
-
This step tests for low line pressure.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls | |
2 | Visually inspect the transmission cooling system for fluid leaks. Refer to Fluid Leak Diagnosis . Was a condition found? | -- | ||
Was the transmission fluid checking procedure performed? | -- | Go to Transmission Fluid Check | ||
Important: Before clearing the DTCs, use the Scan Tool in order to record the Failure Records for reference. Using the Clear Info function will erase the stored Failure Records from the PCM. Did the commanded gear ratio match the specified ranges? | Reverse: 2.33:1 to 2.43:1 1st: 2.87:1 to 2.97:1 2nd: 1.52:1 to 1.62:1 3rd: 0.95:1 to 1.05:1 4th: 0.65:1 to 0.75:1 | Go to Diagnostic Aids | ||
Perform the line pressure check. Refer to the Line Pressure Check . Was a condition found? | -- | Go to Symptom Diagnosis | ||
6 | Inspect for clutch slippage. Refer to Symptom Diagnosis . Was a condition found and corrected? | -- | -- | |
7 | Repair the transmission cooling system as necessary. Refer to Fluid Leak Diagnosis . Is the repair complete? | -- | -- | |
8 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Reverse: 2.33:1 to 2.43:1 1st: 2.87:1 to 2.97:1 2nd: 1.52:1 to 1.62:1 3rd: 0.95:1 to 1.05:1 4th: 0.65:1 to 0.75:1 | System OK |
