Circuit Description
The 2-3 shift solenoid (2-3 SS) valve is fed ignition voltage by circuit 1039/839
and the ground path is provided by the PCM, depending on the solenoids commanded
state. When the PCM commands the solenoid OFF, a ground path is not provided
and the filtered line pressure that is fed to the solenoid is exhausted. When
the PCM commands the solenoid ON, a ground path is provided and the exhaust
port is blocked, stopping the exhaust of line pressure.
The PCM identifies a 2-3 SS valve performance condition by monitoring
the commanded gear versus the gear ratio.
If the PCM detects the gear ratio outside the limits for a particular
commanded gear, then DTC P0756 sets. DTC P0756 is a Type D DTC.
Conditions for Running the DTC
| • | No TP sensor DTCs P0121, P0122 or P0123 are set. |
| • | No VSS DTCs P0502 or P0503 are set. |
| • | No A/T ISS sensor DTCs P0716 or P0717 are set. |
| • | No 1-2, 3-4 SS valve electrical DTC P0753 is set. |
| • | No 2-3 SS valve electrical DTC P0758 is set. |
| • | No TFP manual valve position switch DTC P1810 is set. |
| • | No TCC PWM solenoid valve DTC P1860 is set. |
| • | The engine speed is greater than 500 RPM for 5 seconds
and not in fuel shut off. |
| • | The transmission fluid temperature is greater than 20°C (68°F). |
| • | The transmission is not in PARK or NEUTRAL. |
Conditions for Setting the DTC
DTC P0756 sets when Case 1 occurs once or Case 2
occurs twice during the same trip:
Case 1 (Stuck Off)
| • | The PCM commands 1st gear and: |
| - | the vehicle speed is greater than 11 km/h (7 mph); |
| - | the TP angle is greater than 8%; |
| - | the gear ratio indicates 4th gear (0.65:1 to 0.75:1) for 2 seconds. |
| • | The PCM commands 2nd gear and: |
| - | the vehicle speed is greater than 11 km/h (7 mph); |
| - | the TP angle is greater than 8%; |
| - | the gear ratio indicates 3rd gear (0.95:1 to 1.05:1) for 1 second. |
Case 2 (Stuck On)
| • | The PCM commands 3rd gear and: |
| - | the vehicle speed is greater than 11 km/h (7 mph); |
| - | the TP angle is greater than 8%; |
| - | the gear ratio indicates 2nd gear (1.52:1 to 1.62:1) for 3 seconds. |
| • | The PCM commands 4th gear and: |
| - | the vehicle speed is 35-82 mph; |
| - | the gear ratio indicates 1.05:1 to 2.97:1 for 3 seconds. |
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM commands 3rd gear. |
| • | The PCM commands maximum line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM stores DTC P0756 in PCM history. |
Conditions for Clearing the DTC
| • | A scan tool clears the DTC from the PCM history. |
| • | The PCM clears the DTC from the PCM history if the vehicle completes
40 consecutive warm-up cycles without a 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 transmission fluid for sediment. |
| • | Inspect the transmission filter for debris. |
| • | Ensure that the scan tool commanded gear has correct solenoid
states and ratio. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Important: Do not drive the vehicle for an extended period of time, as additional
internal damage may occur.
-
This
step tests that the PCM commanded all the shifts, that all the shift solenoid
valves responded correctly, but that all the shifts did not occur.
DTC P0756 2-3 Shift Solenoid Valve -- Performance
Step
| Action
| Value(s)
| Yes
| No
|
1
| Was the Powertrain On-Board Diagnostic
(OBD) System Check performed?
| --
|
Go to Step
2
| Go to
Powertrain On Board Diagnostic (OBD) System Check
in Engine Controls
|
2
| Was the transmission
fluid checking procedure performed?
| --
|
Go to Step
3
| Go to
Transmission Fluid Check
|
3
|
- Install the Scan Tool
.
- Turn the ignition switch to the RUN position.
Important: Before clearing the DTCs, use the Scan Tool
in order to record the Freeze Frame and Failure Records for
reference. Using the Clear Info function will erase the stored Freeze Frame
and Failure Records from the PCM.
- Record the Freeze Frame and Failure Records.
- Clear the DTCs.
- Drive the vehicle in D4 range, under the following conditions:
Accelerate the vehicle, ensuring that the PCM commands 1st, 2nd, 3rd
and 4th gears.
Was a 4-3-3-4 or 1-2-2-1 shift pattern detected?
| --
|
Go to Step 4
| Go to Diagnostic Aids
|
4
| Inspect the 2-3 shift solenoid valve/hydraulic circuit
for the following conditions:
| • | An internal malfunction. |
| • | Damaged seals on one or both of the shift solenoid valves. |
| | Refer to Shift Solenoid Leak Test
. |
Did you find and correct the condition?
| --
|
Go to Step 5
| --
|
5
| Perform the following procedure in order to verify the repair:
- Select DTC.
- Select Clear Info.
- Road test the vehicle in D4. Ensure that the transmission completes
the 1-2, 2-3 and 3-4 upshifts with the TP angle at least 8%.
- Monitor TP angle, current gear and gear ratio on the Scan Tool
. Ensure that the gear ratio values
are correct for each gear, for at least 1 second per shift.
- Select Specific DTC.
- Enter DTC P0756.
Has the test run and passed?
| 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
|
Go to Step
1
|
