Diagnostic Instructions
DTC Descriptor
DTC P1731: 1st Gear Ratio Incorrect - with Engine Brake
Diagnostic Fault Information
Component
| Cause
| DTCs
|
Valve Body Assembly
|
| • | incorrect transmission fluid level |
| • | clogged hydraulic system |
| • | plugged or restricted passages |
| P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780, P1731
|
Line Pressure Control (PC) Solenoid Valve
|
| • | incorrect transmission fluid level |
| • | clogged hydraulic system |
| • | mechanically stuck in the applied position |
| P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780, P1731
|
Shift Solenoid (SS) Valve
|
| • | incorrect transmission fluid level |
| • | clogged hydraulic system |
| • | mechanically stuck in the applied position |
| P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780, P1731
|
Pressure Control (PC) Solenoid Valve
|
| • | incorrect transmission fluid level |
| • | clogged hydraulic system |
| • | mechanically stuck in the applied position |
| P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780, P1731
|
Fluid Pump Cover Assembly
| Fluid pump cover vanes and fluid pump rotor broken
| P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780, P1731
|
Circuit/System Description
The shift control solenoid assembly (SLC1, SLC2, SLC3, SLB1) and the line pressure control solenoid (SLT) are installed on the front valve body. The solenoids linearly control hydraulic pressure in response to signals output from the transmission control
module (TCM). SLC1, SLC2, SLC3, SLB1 controls hydraulic pressure to the clutches (C1, C2, C3) and brake (B1) for smooth shifting. According to each shift control solenoid assembly, the transmission shifts from 1st gear into 6th gear and vice versa. As a fail-safe
function, if any shift control solenoid assembly abnormality occurs, the TCM will disable the current to the solenoids.
Conditions for Running the DTC
| • | The ignition voltage is between 10.2 V and 15.5 V. |
| • | The engine speed is greater than 500 RPM for 2 seconds. |
| • | The transmission is not in emergency mode. |
| • | TCM communication is normal. |
| • | Transmission fluid temperature is higher than 20°C (68°F). |
| • | DTCs P0716. P0717, P0721 and P0722 are not set. |
Conditions for Setting the DTC
| • | Driving in D range, 1st gear with engine break. |
| • | Engine torque is less than 1 N·m (0.75 ft-lb). |
| • | Measured gear ratio deviates more than 20% from expected ratio. |
| • | Determined after 12 times lasting 1 s or more. |
Action Taken When the DTC Sets
| • | DTC P1731 is a Type C DTC |
| • | Torque limitation in "D" range 150 N·m (110 ft-lb), in "R" range 170 N·m (125 ft-lb). |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM turns OFF all solenoids. |
| • | The TCM allows the vehicle to operate only in second gear and "R" range after a stop. |
Conditions for Clearing the DTC
| • | DTC P1731 is a Type C DTC. |
| • | Measured gear ratio deviates less than 4% from expected ratio. |
Diagnostic Aids
When attempting to set transmission performance DTCs, observe the Freeze Frame and Failure Records to assist in duplicating the failure conditions. Ensure the transmission fluid level, colour and odor is correct and there are no leaks. If there are any
other transmission DTCs set, diagnose those first.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Description and Operation
Transmission Component and System Description
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify the transmission fluid level , colour and odor is correct.
- Operate the vehicle to induce a shift from fifth to sixth gear while observing the following scan tool parameters. The scan tool parameters has to change the proper value referring to the current gear, compare the proper values with: transmission
system description and operation
Transmission System Description and Operation. Perform this action 2 times.
| • | Clutch Pressure Control Solenoid Valve 1 Current |
| • | Clutch Pressure Control Solenoid Valve 2 Current |
| • | Clutch Pressure Control Solenoid Valve 3 Current |
| • | Brake Band Pressure Control Solenoid Valve Current |
| ⇒ | If the scan tool parameter does not change the proper value and no other DTC than P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780, P1731 is set, go to Circuit/System Testing. |
| ⇒ | If any other DTC is set, diagnose that DTC first. |
Circuit/System Testing
Dynamic Test
- Perform the line pressure check
Line Pressure Check.
- Perform the transmission fluid check
Transmission Fluid Check.
- If all circuits test normal, replace the K71 Transmission Control Module (TCM). Verify the DTC does not reset.
| ⇒ | If the DTC resets replace the control valve body. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
