SES Light Help

[TransAm11973]

Hey guys I am throwing a SES light. Code is P0751 lower transmission, shift solenoid A circuit perf stuck off. Gonna take it back to the place that rebuilt my transmission, have a warrenty on it. Any info or help would be greatly appreciated.

[konigandy6]

Circuit Description
The 1-2 shift solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The 1-2 SS valve is a normally-open exhaust valve that is used with the 2-3 SS valve, in order to allow four different shifting combinations.

When the PCM detects a 1-1-4-4 or a 2-2-3-3 shift pattern, depending on the state of the mechanical failure, then DTC P0751 sets. DTC P0751 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 engine speed is greater than 450 RPM for 5 seconds.

• The engine is not in fuel cutoff.

• The TP angle is 10-35%.

• The TP angle is constant +/-5%.

• The gear range is D4.

• The transmission fluid temperature is 20-130°C (68-266°F).

• The PCM commands a 1-2, 2-3, and 3-4 shift.

• The TCC is commanded ON.

• The vehicle speed is greater than 8 km/h (5 mph).

Conditions for Setting the DTC
DTC P0751 sets if the following conditions occur three times:

• Within 2 seconds, the engine speed in 2nd gear is 80 RPM greater than the last speed in 1st gear.

• Within 2 seconds, the engine speed in 3rd gear is 50 RPM less than the last speed in 2nd gear.

• Within 2 seconds, the engine speed in 4th gear is 10 RPM greater than the last speed in 3rd gear.

All of the above conditions are met and one of the following conditions occurs:

Condition 1
• The speed ratio is 0.95 to 1.2 (speed ratio is engine speed divided by transmission output speed).

• The TCC slip speed is 200-1000 RPM for 4 seconds.

Condition 2
• The speed ratio is 0.65 to 0.8.

• The TCC slip speed is -20 to +40 RPM for 4 seconds.

Action Taken When the DTC Sets
• The PCM illuminates the malfunction indicator lamp (MIL).

• The PCM commands D2 line pressure.

• The PCM inhibits 3-2 downshifts if the vehicle speed is greater than 48 km/h (30 mph).

• 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 P0751 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.

• Other internal transmission failures may cause more than one shift to occur.

• Refer to the Shift Solenoid Valve State and Gear Ratio table.

[konigandy6]

Don't know if that helps at all... but I just punched the DTC into GM's service info site. Might need to talk to a GM trans tech.

[TransAm11973]

yeah thanks, i had looked at the same thing. Hoping someone on here with a decent amount of trans repair experience can give me a little more indepth info on it. How hard to fix etc. thanks for the post up its good info