P0751
Diagnostic Chart:
Diagnostic Chart (cont'd):
Diagnostic Chart:
Shift Solenoid:
CIRCUIT DESCRIPTION
The 1-2 Shift Solenoid Valve (1-2 SS Valve) controls fluid flow acting on the 1-2 shift valve and the 3-4 shift valve. The 1-2 SS Valve is a normally-open exhaust valve. Used with the 2-3 Shift Solenoid Valve (2-3 SS Valve), the 1-2 SS Valve allows four different shifting combinations.
When the PCM detects a 1-1-4-4 only or a 2-2-3-3 only shift pattern, then DTC P0751 sets. The pattern that the PCM detects depends on the mechanical failure. DTC P0751 is a type B DTC.
CONDITIONS FOR SETTING THE DTC
No Throttle Position (TP) DTCs P0122 or P0123
No Vehicle Speed Sensor (VSS) 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
Previous shift time is greater than 0.0 seconds.
The gear range is D4.
The engine speed is greater than 400 RPM for 8 seconds and not in fuel cutoff.
The vehicle speed is greater than 8 km/h (5 mph).
Transmission temperature is between 20 and 130°C (68 and 268°F).
The traction control is not active.
All the above conditions have been met and the combination of Conditions 1,2,3, and 4 or 1,2,3, and 5 occur two consecutive times.
Condition 1
- Commanded 1-2 shift
- The TP angle is 8-42%.
- The TP angle is constant within +1-3%.
- Vehicle speed is 8-64 km/h (5-40 mph).
- Within 3.75 seconds, the engine speed in 2nd gear must be 150 RPM greater than the last speed in 1st gear.
Condition 2
- Commanded 2-3 shift
- The TP angle is 9-32%.
- The TP angle is constant within +1-3%.
- Vehicle speed is between 32 and 72 km/h (20 and 45 mph).
- Within 2.25 seconds, the engine speed in 3rd gear must be 150 RPM less than the last speed in 2nd gear.
Condition 3
- Commanded 3-4 shift
- The TP angle is 9-27%.
- The TP angle is constant within +/-3%.
- The vehicle speed is 68-105 km/h (42-65 mph).
- Within 3.5 seconds the engine speed in 3rd gear must be 15 RPM greater than the last speed in 4th gear.
Condition 4
- Commanded 4th gear
- The TCC is ON.
- The TP angle is 9-27%.
- The speed ratio is 42-47 (the speed ratio is the engine speed the output speed).
- The TCC slip speed is 500-1000 RPM for 5 seconds.
Condition 5
- Commanded 4th gear
- The TCC is ON.
- The TP is 9-27%.
- The Speed ratio is 30-34 (the speed ratio is the engine speed + the output speed). The TCC slip speed is 2040 RPM for 5 seconds.
ACTION TAKEN WHEN THE DTC SETS
The PCM illuminates the Malfunction Indicator Lamp (MIL).
CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
- A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
- The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.
DIAGNOSTIC AIDS
- Verify that the transmission meets the specifications in the Shift Speed.
- More than one shift may occur because of other internal transmission failures.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic chart.
2. Step 2 verifies that the TFP Valve Position Switch is functioning normally.
3. Step 3 verifies that the following sequence occurs:
- The scan tool commands all shifts.
- All the shift solenoids respond properly. Not all the shifts occur.