| Table 1: | 4L80-E Range Reference, modified for DTCs P1870 & P1871 |
| Table 2: | P0730 (97 C/K & G600 VCM) |
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 Vehicle Control Module (VCM) calculates the gear ratio based on the Automatic Transmission Input Shaft Speed (A/T ISS) and Output Shaft Speed (OSS) Sensor readings. The VCM compares the known transmission gear ratio to the calculated ratio for the selected gear ranges.
If the VCM detects an unknown transmission gear ratio, then DTC P0730 sets. DTC P0730 is a type D DTC.
Conditions for Setting the DTC
The following conditions are met for 10 seconds.
| • | No Manifold Absolute Pressure (MAP) DTCs P0106, P0107, or P0108. |
| • | No Throttle Position (TP) DTCs P0121, P0122, or P0123. |
| • | No OSS DTCs P0502 or PO503. |
| • | No A/T ISS DTCs P0716 or P0717. |
| • | No TFP Val. Position Sw. DTC P1810. |
| • | No 4WD Low DTC P1875. |
| • | The Vehicle Speed is greater than 7 km/h (4 mph). |
| • | The TP Angle is greater than 15%. |
| • | The TFT is greater than 20°C (68°F). |
| • | 30 seconds must have elapsed since the last gear range change. |
| • | The engine torque is 110-542 N·m (80-400 lb ft). |
| • | The engine is running greater than 475 RPM for 5 seconds. |
| • | The Gear Ratio is one of the following: |
| - | Greater than 2.50 or less than 2.42 |
| - | Greater than 1.50 or less than 1.44 |
| - | Greater than 1.03 or less than 0.25 |
| - | Greater than 2.12 or less than 2.04 |
Action Taken When the DTC Sets
| • | The VCM does not illuminate the Malfunction Indicator Lamp (MIL). |
| • | The VCM commands maximum line pressure. |
| • | The VCM freezes shift adapts. |
| • | DTC P0730 is stored in VCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM. |
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 A/T OSS or A/T 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 Val. Position Sw. could set DTC P1810.
-
This step tests for proper ratios in each commanded gear state.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||||||
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 for reference. The Clear Info function will erase the stored Failure Records from the VCM. Does the scan tool TFP Switch A/B/C display match each selected gear range? (Refer to the Range Signal table). | -- | Go to DTC P1810 TFP Val. Position Switch in this section | ||||||||||||||
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 | Refer to Diagnostic Aids | ||||||||||||||
5 |
Refer to the Line Pressure Check . Is the line pressure within specifications for each selected gear range? | -- | ||||||||||||||
6 |
Refer to Changing the Fluid and Filter, in On-Vehicle Service. Did you find excessive contamination? | -- | Go to Transmission Overhaul Procedure, in Unit Repair | |||||||||||||
7 | Inspect the transmission for the following problems:
Did you find the condition? | -- | Go to Transmission Overhaul Procedure, in Unit Repair | |||||||||||||
8 | Is the system line pressure low only in the specific gear which indicated an incorrect gear ratio? | -- | Go to System Diagnosis Table; Low Line Pressure | |||||||||||||
9 | Inspect for fluid pressure loss in the following areas:
Did you find the condition? | -- | Go to Transmission Overhaul Procedure, in Unit Repair | |||||||||||||
10 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
