P0751

Shift Solenoid:

CIRCUIT DESCRIPTION
The 1-2 Shift Solenoid Valve (1-2 SS Valve) controls the fluid flow acting on the 1-2 and 3-4 shift valves. The solenoid is a normally-open exhaust valve. With the 2-3 Shift Solenoid Valve (2-3 SS Valve), the 1-2 SS Valve allows four different shifting combinations. When the VCM detects a 1-1-4-4 only or 2-2-3-3 only shift pattern depending on the state of the mechanical failure, then DTC P0751 sets. DTC P0751 is a type B DTC.

CONDITIONS FOR SETTING THE DTC
^ No TP DTCs P0122 or P0123.
^ No VSS Assy. DTC P0502.
^ No TCC Stuck ON DTC P0742.
^ No 1-2 SS Valve DTC P0753.
^ No 2-3 SS Valve DTC P0758.
^ No TFP Val. Position Sw. DTC P1810.
^ No TCC PWM Sol. Valve DTC P1860.
^ No TCC Sol. Valve DTC P1864.
^ No 3-2 SS Valve Assy. DTC P1886.
^ The gear range is D4.
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The engine speed is greater than 400 RPM for 8 seconds.
^ The transmission temperature is 20-130°C (68-266°F).
^ Not in fuel cutoff.

All the above conditions are met and the combination of Case 1,2,3, and 4 or 1,2,3, and 5 occurs two consecutive times.

Case 1
^ The VCM commands a 1-2 shift.
^ The TP angle is 18-45%.
^ The TP angle is constant within +/- 3%.
^ The vehicle speed is 856 km/h (5-35 mph).
^ Within 3 seconds, the engine speed in 2nd gear is 100 RPM greater than the last speed in 1st gear.

Case 2
^ The VCM commands a 2-3 shift.
^ The TP angle is 18-45%.
^ The TP angle is constant within +/- 3%.
^ The vehicle speed is 32-80 km/h (20-50 mph).
^ Within 2 seconds, the engine speed in 3rd gear is 150 RPM less than the last speed in 2nd gear.

Case 3
^ The VCM commands a 3-4 shift.
^ The TP angle is 1445%.
^ The TP angle is constant within +/- 3%.
^ The vehicle speed is 48105 km/h (30-65 mph).
^ Within 3.5 seconds, the engine speed in 3rd gear is 20 RPM greater than the last speed in 4th gear.

Case 4
^ The VCM commands 4th gear.
^ The TCC is ON.
^ The TP angle is 9-35%.
^ The speed ratio is 0.85-1.2 (speed ratio is engine speed divided by output speed).
^ The TCC slip speed is 200-1000 RPM for 4 seconds.

Case 5
^ The VCM commands 4th gear.
^ The TCC is ON.
^ The TP is 9-35%.
^ The speed ratio is 0.6-0.8.
^ The TCC slip speed is -20 to +40 RPM for 4 seconds.

ACTION TAKEN WHEN THE DTC SETS
The VCM illuminates the Malfunction Indicator Lamp (MIL).

CONDITIONS FOR CLEARING THE MIL/DTC
^ The VCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
^ A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.

DIAGNOSTIC AIDS
^ Verify that the transmission meets the specifications in the 4L60E shift speed chart.
^ 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 chart.

2. This Step tests that the scan tool commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.