Circuit Description
The 2-3 shift solenoid (SS) valve is a normally-open exhaust
valve that, in conjunction with the 1-2 shift solenoid (SS) valve,
allows four different shifting combinations. Refer to
Shift Solenoid Valve State and Gear Ratio
. The 2-3 SS valve
is attached to the control valve body, within the transmission.
The PCM monitors the actual gear ratio, and compares the actual gear
ratio with the commanded gear ratio. DTC P0757 sets under two conditions:
• | A stuck OFF 2-3 SS valve |
• | A stuck OFF 2-3 shift valve |
When the PCM detects a 1-2-2-1 shift pattern, then
DTC P0757 sets. DTC P0757 is a type A DTC.
Conditions for Running the DTC
• | No TP DTCs P0121, P0122 or P0123. |
• | No VSS DTCs P0502 or P0503. |
• | No AT ISS DTCs P0716 or P0717. |
• | No shift solenoid electrical DTCs P0753 or P0758. |
• | No engine torque DTC P1644. |
• | No TFP manual valve position switch DTC P1810. |
• | The system voltage is 8-18 volts. |
• | The engine run time is greater than 5 seconds. |
• | The TFP manual valve position switch is not indicating Park, Reverse,
or Neutral. |
• | The transmission fluid temperature is greater than 21°C (70°F). |
• | The TP is greater than 8 percent. |
• | The input speed is greater than 50 RPM. |
• | The vehicle speed is greater than 8 km/h (5 mph). |
Conditions for Setting the DTC
• | The PCM commands 3rd gear and the gear ratio is 1.54:1-1.71:1,
2nd gear, for 3 seconds. |
• | The PCM commands 4th gear and the gear ratio is 2.87:1-3.13:1,
1st gear, for 2 seconds. |
Action Taken When the DTC Sets
• | The PCM illuminates the malfunction indicator lamp (MIL). |
• | The PCM commands an immediate landing to 2nd gear. |
• | The PCM commands maximum line pressure. |
• | The PCM inhibits TCC engagement. |
• | The PCM freezes transmission adapt functions. |
• | The PCM records the operating conditions when the Conditions for
Setting the DTC are met. The PCM stores this information as Freeze Frame
and Failure Records. |
• | The PCM stores DTC P0757 in PCM history. |
Conditions for Clearing the MIL/DTC
• | The PCM turns OFF the MIL during the third consecutive trip in
which the diagnostic test runs and passes. |
• | A scan tool can clear the MIL/DTC. |
• | The PCM clears the DTC from PCM history if the vehicle completes
40 warm-up cycles without an emission-related
diagnostic fault occurring. |
• | The PCM cancels the DTC default actions when the ignition switch
is OFF long enough in order to power down the PCM. |
Diagnostic Aids
• | If you clear DTC P0757, and then cannot reset DTC P0757,
inspect for the following conditions: |
- | Restricted fluid circuits |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies a 1-2-2-1
shift pattern.
-
This step tests for a mechanical or hydraulic
condition causing the 2-3 SS valve to be stuck OFF, or the circuit
to be applied.
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
|
2
| Did you perform the Transmission Fluid Checking
Procedure?
| --
| Go to
Step 3
| Go to
Transmission Fluid Check
|
3
|
- Install a scan tool.
- Turn ON the ignition, with the engine OFF.
Important: Before clearing the DTC, use the scan tool in order to record the Freeze
Frame and Failure Records. Using the Clear Info function erases the Freeze
Frame and Failure Records from the PCM.
- Record the DTC Freeze Frame and Failure Records.
- Clear the DTC.
- Use the scan tool snapshot mode in order to record current gear
and gear ratio.
- Drive the vehicle in D4, in order to obtain a 1-2, 2-3
and 3-4 shifts with a TP greater than 8%.
Are current gear and gear ratio within the specified values?
| 1st/4th
2.87:1-3.13:1
2nd/3rd
1.54:1-1.71:1
| Go to
Step 4
| Go to Diagnostic Aids
|
4
|
- Inspect the 2-3 shift circuit for the following conditions:
• | 2-3 SS valve mechanically stuck OFF. |
• | Damaged 2-3 SS valve O-ring |
• | 2-3 shift valve stuck in the released position. |
- Repair the circuit as necessary.
Refer to
Transmission Overhaul
in Transmission Unit Repair Manual.
Did you complete the repair?
| --
| Go to
Step 5
| --
|
5
| Perform the following
procedure in order to verify the repair:
- Select DTC.
- Select Clear Info.
- Operate the vehicle under the following conditions:
• | Drive the vehicle in D4. |
• | Allow the transmission to shift through all the gears. |
• | Monitor the current gear and gear ratios. The actual gear ratios
must match the commanded gears for 0.75 seconds, for all gears. |
- Select Specific DTC.
- Enter DTC P0757.
Has the test run and passed?
| --
| System OK
| Go to
Step 1
|