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. The 2-3 SS valve is attached to the lower 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 P0756 sets under two conditions:
| • | A stuck ON 2-3 SS valve |
| • | A stuck ON 2-3 shift valve |
If the PCM detects a 4-3-3-4 shift pattern, then DTC P0756 sets. DTC P0756 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 IMS DTCs P1820, P1822, P1823 or P1825. |
| • | No shift solenoid electrical DTCs P1842, P1843, P1845 or P1847. |
| • | The engine run time is greater than 5 seconds. |
| • | The IMS indicates D1, D2, D3 or D4. |
| • | The transmission fluid temperature is 20-133°C (68-271°F). |
| • | The TP angle is 10 percent or greater. |
| • | The vehicle speed is 8 km/h (5 mph) or greater. |
| • | The engine torque is 80-395 N·m (59-291 lb ft). |
Conditions for Setting the DTC
The following conditions occur twice during the same trip:
| • | The PCM commands 1st gear and the gear ratio is 0.65:1-0.71:1, 4th gear, for 1 second. |
| • | The PCM commands 2nd gear and the gear ratio is 0.95:1-1.05:1, 3rd gear, for 0.5 second. |
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 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. |
Diagnostic Aids
| • | If you clear DTC P0756, and then cannot reset DTC P0756, the following conditions may exist: |
| - | Fluid contamination |
| - | Plugged fluid circuits |
| - | Restricted fluid circuits |
| • | Refer to Shift Solenoid Valve State and Gear Ratio . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies a 4-3-3-4 shift pattern.
-
This step tests for a mechanical or hydraulic condition causing the 2-3 SS valve to be stuck ON, 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 | ||||||
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. Are commanded gear and gear ratio within the specified parameters? | 1st/4th 0.65:1-0.71:1 2nd/3rd 0.95:1-1.05:1 | Go to Step 4 | Go to Diagnostic Aids | |||||||
Refer to Transmission Overhaul in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the repair? | -- | Go to Step 5 | -- | |||||||
5 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK | Go to Step 1 |
