P0755

DTC P0755 Transaxle Shift B Solenoid Problem Diagnostic Chart:

Transmission Controls' Wiring Schematic:

CIRCUIT DESCRIPTION
The 4T60E is an electronically shifted transaxle. Within the transaxle are 4 solenoids for shift and Torque Converter Clutch (TCC) control. The shift A solenoid is energized for lst and 4th gear operation. The shift B is energized for lst gear as well as 2nd gear operation. The other two solenoids are for TCC operation. We will deal with shift control only here.

When the ignition switch is turned "ON," both shift solenoids receive 12 volts from CKT 241. The Powertrain Control Module (PCM) will ground CKT 1223 and CKT 1222 for lst gear until a shift to second gear is commanded. When vehicle speed and Throttle Position (TP) sensor reach calibrated values the PCM will turn "OFF" the ground for the shift A solenoid and 2nd gear is engaged. Further increases in speed will result in the PCM turning "OFF" the ground for the shift B solenoid, engaging 3rd gear. In 3rd gear, both solenoids are de-energized. In 4th gear, only the shift A solenoid is energized.

All Park Reverse Neutral Drive Low (PRNDL) indications are ignored as far as transaxle shifting is concerned except for manual low gear. If the PRNDL inputs indicate manual low has been selected the PCM will keep both shift solenoids energized until 5400 RPM, when the PCM will force a shift by de-energizing the shift A solenoid. Manual 2nd and manual 3rd are controlled hydraulically within the transaxle.


DIAGNOSTIC TROUBLE CODE (DTC) PO755 WILL SET WHEN
^ Shift B is failed in the "OFF" position, which will cause the transaxle to be in 4th gear. and:

- Desired gear is 1st.
- Throttle angle is greater than 3%.
- Vehicle Speed Sensor (VSS) is greater than 5 mph.
- No DTC P0122, P0l23, or P0502 present.
- Engine speed divided by vehicle speed does not indicate 1st gear.
- Above conditions for 3.5 seconds.

Or

^ Shift B is failed in the "ON" position, which will cause the transaxle to be in 1st gear and:

- Desired gear is 4th.
- PRNDL is in 3rd or 4th.
- Throttle angle is greater than 10%.
- No DTC P0122, P0123, or P0705 present.
- Engine speed divided by vehicle speed does not indicate 4th gear.


ACTION TAKEN (PCM WILL DEFAULT TO)
When DTC P0755 is set, the transaxle will be forced into 3rd gear. If DTC P0755 is set due to a grounded CKT 1223, you will have 1st and 2nd gear operation only. If CKT 1223 is open, you will have 3rd and 4th gear operation only. When the fault goes away, you will have normal operation for the balance of the key cycle.

DTC P0755 does not illuminate the Malfunction Indicator Lamp (MIL).