DTC P0756 2-3 Shift Solenoid Valve Performance 5.7L
Circuit Description
The 2-3 shift solenoid (SS) valve controls the fluid flow acting on
the 2-3 shift valves. The 2-3 SS valve is a normally-open exhaust valve that
is used with the 1-2 SS valve in order to allow four different shifting
combinations.
When the PCM detects a 1-2-2-1 or a 4-3-3-4 shift pattern, depending
on the state of the mechanical failure, then DTC P0756 sets. DTC P0756
is a type A DTC.
Conditions for Running the DTC
| • | No TP sensor DTCs P0122 or P0123. |
| • | No VSS assembly DTCs P0502 or P0503. |
| • | No TCC solenoid valve DTC P0740. |
| • | No TCC stuck ON DTC P0742. |
| • | No 1-2 SS valve DTC P0753. |
| • | No 2-3 SS valve DTC P0758. |
| • | No 3-2 SS valve assembly DTC P0785. |
| • | No TFP manual valve position switch DTC P1810. |
| • | No TCC PWM solenoid valve DTC P1860. |
| • | The vehicle speed is greater than 8 km/h (5 mph). |
| • | The engine vacuum is 0-105 kPa. |
| • | The engine torque is 40-400 lb ft. |
| • | The TP angle is 10-50%. |
| • | The TP angle is constant within +/-7%. |
| • | The engine speed is greater than 450 RPM for 5 seconds. |
| • | The engine is not in fuel cutoff. |
| • | The transmission fluid temperature is 20-130°C (68-266°F). |
| • | The PCM commands a 1-2, 2-3, and 3-4 shift. |
Conditions for Setting the DTC
DTC P0756 sets if the following conditions occur three times:
| • | Third gear is commanded for 2 to 6 seconds. |
| • | The speed ratio in 3rd gear does not drop more than 0.3 from the
last speed ratio in 2nd gear (speed ratio is engine speed divided by transmission
output speed). |
| • | The TCC slip speed in 3rd gear remains 400 RPM higher than
the last TCC slip speed in 2nd gear. |
All of the above conditions are met for 1.5 seconds and one of
the following conditions occurs:
Condition 1
| • | The engine torque is 0-400 lb ft. |
| • | First gear is commanded. |
| • | The TP angle is greater than 25%. |
| • | The transmission output speed is 400-1500 RPM. |
| • | The speed ratio is 0.7 to 3.0. |
| • | The TCC slip speed is -2000 to 0 RPM. |
| • | All conditions are met for 1.5 seconds. |
Condition 2
| • | Fourth gear is commanded for 1.5 seconds. |
| • | The transmission output speed is 1000-3000 RPM. |
| • | The speed ratio is 1.68 to 3.0. |
| • | The TCC slip speed is 1000 to 3000 RPM. |
| • | All conditions are met for 1 second. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | The PCM commands 3rd gear only. |
| • | The PCM commands maximum line pressure. |
| • | The PCM inhibits TCC engagement. |
| • | The PCM freezes shift adapts from being updated. |
| • | 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 P0756 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 fault no longer
exists and/or the ignition switch is OFF long enough in order to power down
the PCM. |
Diagnostic Aids
| • | Verify that the transmission meets the specifications in the
Shift Speed
table. |
| • | Ensure that the proper transmission oil filter assembly is being
used in conjunction with the applicable transmission oil pan. |
| • | Other internal transmission failures may cause more than one shift
to occur. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that the PCM commanded all shifts, and all shift
solenoids responded correctly, but all the shifts did not occur.
DTC P0756 2-3 SS Valve Performance (5.7L)
Step
| Action
| Value(s)
| Yes
| No
|
1
| Did you perform the Powertrain Diagnostic System Check?
| --
|
Go to Step
2
| Go to
Powertrain On Board Diagnostic (OBD) System Check
in Engine Controls
|
2
|
- 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.
- Drive the vehicle in D4 range under the following conditions:
Accelerate the vehicle, ensuring that the PCM commands 1st, 2nd, 3rd
and 4th gears.
Did you detect a 1-2-2-1 or 4-3-3-4 shift pattern?
| --
|
Go to Step 3
| Go to
Diagnostic Aids
|
3
| Inspect the shift solenoid/hydraulic
circuit for the following conditions:
| • | An internal malfunction |
| • | Damaged seals on the shift solenoid valve. |
| | Refer to Shift Solenoid Leak Test
. |
Did you find and correct the condition?
| --
|
Go to Step 4
| --
|
4
| Perform the following procedure
in order to verify the repair:
- Select DTC.
- Select Clear Info.
- Drive the vehicle in D4 under the following conditions (only if
traffic and road conditions permit):
| • | Hold the throttle at 40% and accelerate to 64 km/h (40 mph). |
| • | Stop the vehicle, engine idling. |
| • | Hold the throttle at 15% and accelerate to 80 km/h (55 mph). |
- Select Specific DTC.
- Enter DTC P0756.
Has the test run and passed?
| --
| System OK
|
Go to Step 1
|
