DTC P0730 Incorrect Gear Ratio Gas LQ4
| Table 1: | 4L80-E Range Reference, modified for DTCs P1870 & P1871 |
| Table 2: | DTC P0730 |
Range | Gear | 1-2 Sol | 2-3 Sol | Fourth Clutch | Overrun Clutch | O/D Roller Clutch | FWD Clutch | Direct Clutch | Front Band | Interm. Sprag Clutch | Interm Clutch | Lo Roller Clutch | Rear Band |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Overdrive | 1st | On | Off | -- | -- | H | A | -- | -- | * | -- | H | -- |
2nd | Off | Off | -- | -- | H | A | -- | -- | H | A | O | -- | |
3rd | Off | On | -- | -- | H | A | A | -- | O | A | O | -- | |
4th | On | On | A | -- | O | A | A | -- | O | A | O | -- | |
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Circuit Description
The powertrain control module (PCM) calculates the gear ratio based on the automatic transmission input (shaft) speed sensor (ISS) and output (shaft) speed sensor (OSS) readings. The PCM compares the known transmission gear ratio to the calculated ratio for the selected gear ranges.
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 following conditions are met for 10 seconds.
| • | The system voltage is 8.0-18.0 volts. |
| • | No MAP sensor DTCs P0106, P0107, or P0108. |
| • | No TP sensor DTCs P0121, P0122, or P0123. |
| • | No 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 vehicle speed is greater than 8 km/h (5 mph). |
| • | The TP angle is greater than 15%. |
| • | The TFT is greater than 20°C (68°F). |
| • | No gear range change for greater than 6.0 seconds. |
| • | The engine torque is 110 N·m (80 lb ft) to 542 N·m (400 lb ft). |
| • | The engine is running greater than 300 RPM for 7 seconds and not in fuel cutoff. |
Conditions for Setting the DTC
| • | The engine is running longer than 7 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 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
| • | First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
| • | A false or incorrect OSS or 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. |
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? | -- | ||||||||||||||
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Is the procedure complete? | -- | 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? | -- | |||||||||||||||
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 | ||||||||||||||
5 |
Refer to the Line Pressure Check . Is the line pressure within specifications for each selected gear range? | -- | ||||||||||||||
6 |
Refer to Automatic Transmission Fluid and Filter Replacement . Was excessive contamination found? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||||||
7 | Inspect the transmission for the following conditions:
Did you find and correct the condition? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||||||
8 | Is the system line pressure low only in the specific gear which indicated an incorrect gear ratio? | -- | Go to Symptom Diagnosis Low Line Pressure | |||||||||||||
9 | Inspect for fluid pressure loss in the following areas:
Did you find and correct the condition? | -- | Go to Transmission Overhaul in the 4L80-E Section of the Transmission Unit Repair Manual | |||||||||||||
10 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
