Any of you experts out there familiar with the code P0757. The Tech II showed no definition for the trouble code(older software?).

Thanks,
Carlos

 

The long DTC description is below. You also have a service bulletin about this problem as follows:

DTC P0757 Set, SES Lamp Illuminated, Poor Performance of Transmission, Transmission Slipping (Clean Transmission Valve Body and Case Oil Passages of Debris) #01-07-30-038

DTC P0757 Set, SES Lamp Illuminated, Poor Performance of Transmission, Transmission Slipping (Clean Transmission Valve Body and Case Oil Passages of Debris)

Condition
Some customers may comment on any of the following conditions:

The SES lamp is illuminated.
No 3rd and 4th gear.
The transmission does not shift correctly.
The transmission feels like it shifts to Neutral or a loss of drive occurs.
The vehicle free wheels above 48 km/h (30 mph). High RPM needed to overcome the free wheeling.

Cause
The most likely cause is chips or debris plugging the bleed orifice of the 2-3 shift valve. This will cause the transmission to stay in 2nd gear and return to 1st gear when and/or if the PCM attempts a 3-4 shift.

DTC P0757 code may also be set if the 2-3 shift valve were stuck or hung-up in its bore. Inspect the 2-3 shift valve and the 2-3 shuttle valve for free movement or damage and clean the valves, the bore and the valve body passages.

Correction
The 1-2 and 2-3 shift solenoid valves (also called A and B solenoids) are identical devices that control the movement of the 1-2 and 2-3 shift valves (the 3-4 shift valve is not directly controlled by a shift solenoid).

The solenoids are normally-open (not energized electrically) exhaust valves that work in combination to shift the transmission into four different forward gears. Opening and closing the exhaust valves within the solenoids redirect the transmission fluid, hydraulically moving shift valves and the corresponding shifting of the transmission gears.

The PCM energizes (turns On) or de-energizes (turns Off) each solenoid by either grounding or removing the ground to the solenoid through a quad driver (switch) within the PCM. This allows current flow through the coil winding of the solenoid which causes movement of the internal plunger, blocking or opening an internal orifice.

The 2-3 shift solenoid (SS) valve controls the fluid flow acting on the 2-3 shift valves.

The vehicle speed sensor (VSS) assembly provides vehicle speed information to the PCM. The VSS assembly is a permanent magnet (PM) generator. The PM generator produces a pulsing AC voltage as rotor teeth on the transmission output shaft pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. Output voltage varies with speed from a minimum of 0.5 volts at 100 RPM of the transmission output shaft to more than 100 volts at 8000 RPM of the transmission output shaft. The PCM uses the pulsing voltage to determine vehicle speed. The PCM uses the vehicle speed signal to determine shift timing and TCC scheduling.

Estimated gear ratio is calculated by the PCM, using the estimated torque converter turbine speed (estimated turbine speed is calculated from engine speed and engine torque) divided by the transmission output speed (VSS). The estimated gear ratio is displayed on the Tech 2 as a range of 0.00:1 to 8.00:1.

P0757 will be set, stored within the PCM, when the PCM has detected an incorrect shift pattern when both of the following occur:

The PCM commands third gear for 1 second or more.
The engine torque is 68-542 N·m(50-400 lb ft).
The engine speed is greater than 1.44 times the TCC slip speed.
The PCM then computes the estimated gear ratio and then compares the estimated gear ratio with what the third gear ratio should be (1.00:1). If the computed gear ratio is in the range of 1.575:1 to 1.825:1, the PCM has determined the transmission is not in 3 rd gear. It is, in fact, in second gear hydraulically.
All conditions are met for more than 2 seconds.
AND

The PCM commands fourth gear for 1 second or more.
The engine torque is 0-542 N·m(0-400 lb ft).
The engine speed is greater than 1.13 times the TCC slip speed.
The PCM then computes the estimated gear ratio and compares the estimated gear ratio with the expected fourth gear ratio (.696:1). If the computed gear ratio is in the range of 1.8:1 to 3.26:1, the PCM has determined the transmission is not in 4th gear. It is, in fact, in first or second gear hydraulically.
All conditions are met for more than 2 seconds.
The PCM then takes the following actions:

Records the operating conditions when the DTC was set, so it may be retrieved with the Tech 2 from the Freeze frame and Failure Records.
Illuminates the malfunction indicator lamp (MIL).
Commands 3rd gear.
Commands maximum line pressure.
Will not allow TCC engagement.
Freezes transmission shift adapt functions.
Stores the P0757 as a history trouble code when the ignition is shut off.


The long DTC description:

DTC P0757
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 shift pattern, then DTC P0757 sets. DTC P0757 is a type A DTC.

Conditions for Running the DTC
No TP sensor DTCs P1120 or P1220.
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 engine speed is greater than 450 RPM for 5 seconds.
The engine is not in fuel cutoff.
The gear range is D4.
The TP angle is greater than 10 percent.
The transmission fluid temperature is 20-130°C (68-266°F).
The system voltage is 10-18 volts.
The transmission output speed is 150 RPM or greater.
Conditions for Setting the DTC
DTC P0757 sets if both of the following conditions occur:

Condition 1
The PCM commands third gear for 1 second.
The estimated gear ratio is 1.6-1.8.
Speed ratio is 0.5 or greater.
The engine torque is 68-542 N·m (50-400 lb ft).
All conditions are met for 2 seconds.
Condition 2
The PCM commands fourth gear for 1 second.
The estimated gear ratio is 1.8-3.3.
Speed ratio is 0.5 or greater.
The engine torque is 0-542 N·m (0-400 lb ft).
All conditions are met for 2 seconds.
Action Taken When the DTC Sets
The PCM illuminates the malfunction indicator lamp (MIL).
The PCM commands third gear only.
The PCM commands maximum line pressure.
The PCM inhibits TCC engagement.
The PCM inhibits 4th gear if in hot mode.
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.

I hope this helps.

:cheers:

 

It's most likely a result of your TC and built tranny, I had the same problem. I called Ed Wright and he said it's a common problem for "built" transmissions. He asked me to send back the PCM and he made some changes to correct the problem, haven't seen it since.