Here is an explanation of the code.
DTC P0731 : 1ST GEAR FUNCTION
Circuit Description
DTC is detected when transaxle does not shift into 1st gear when commanded by TCM. TCM monitors actual gear position by checking torque converter slip ratio. Torque converter slip ratio is output shaft revolution signal multiplied by engine speed signal from ECM, divided by gear ratio programmed into TCM. DTC is NOT caused by electrical failure of transaxle circuits, but by mechanical failure.
DTC Confirmation Procedure
1. Connect scan tool. Turn ignition on. Using scan tool, select DATA MONITOR for A/T.
2. Ensure output voltage of Transmission Fluid Temperature (TFT) sensor is 0.4 - 1.5 volts. If voltage is out of range, drive to decrease voltage (warm up fluid) or stop engine to increase voltage (cool down fluid).
3. Using scan tool, select 1ST GR FNCTN P0731 of DTC WORK SUPPORT mode for A/T. Press START.
4. Road test vehicle. Accelerate to 12 - 16 MPH with selector lever in "D" position and overdrive on. Release accelerator pedal fully. Ensure scan tool display GEAR shows 2 after releasing pedal.
5. Accelerate to 12 - 16 MPH. Depress accelerator pedal fully until TESTING changes to STOP VEHICLE or COMPLETED. It will take about 3 seconds. Ensure scan tool display GEAR shows 1 when depressing accelerator.
6. Stop vehicle. Ensure OK is displayed. Check for normal shifting.
Diagnostic Procedure
1. Remove valve body. Check shift solenoid valve "A" and "B" operation. See appropriate tests under COMPONENT TESTS. Repair or replace shift solenoid valve assembly as needed. After repairs, see DTC CONFIRMATION PROCEDURE. If shift solenoid valves "A" and "B" are okay, go to next step.
2. Disassemble valve body assembly. Ensure valves, sleeve and plug slide along valve bore under their own weight, and are free of burrs, dents and scratches. Ensure valve springs are free from damage, deformation and fatigue. Repair valve body assembly as necessary. After repairs, see DTC CONFIRMATION PROCEDURE.
The symptom of jerking and stalling could be caused by the trans, air flow or the throttle position sensor. Go through the following to see if you can come up with anything.
DTC P0120: THROTTLE POSITION SENSOR
NOTE: If DTC P0510 is also present, perform diagnosis for DTC P0510 first.
NOTE: Before performing diagnostic procedure, follow testing procedure.
NOTE: Perform the following DTC confirmation tests in order. Check for DTC after each DTC confirmation test is performed. If DTC is set, perform DIAGNOSTIC PROCEDURE. If DTC is not set, turn ignition off for 10 seconds between each DTC confirmation test.
DTC Confirmation Test "A"
NOTE: Before performing confirmation test "A" ensure battery voltage is greater than 10 volts when engine is idling.
Malfunction "A" is detected when ECM receives an excessively low or high voltage from TP sensor. ECM will enter fail - safe mode. Possible causes are:
"Â TP sensor circuit open or shorted.
"Â Defective TP sensor.
To set DTC, turn ignition on. Using scan tool, select DATA MONITOR. Start engine and drive vehicle for at least 5 seconds at 2 MPH or more. Ensure transmission is not in Neutral. If first trip DTC is detected, go to DIAGNOSTIC PROCEDURE.
DTC Confirmation Test "B"
Malfunction "B" is detected when ECM receives a high voltage from TP sensor under light-load driving conditions. Possible causes are:
"Â TP sensor circuit open or shorted.
"Â Defective TP sensor.
"Â Defective fuel injector.
"Â Defective Camshaft Position (CMP) sensor.
"Â Defective Mass Airflow (MAF) sensor.
To set DTC, turn ignition on. Using scan tool, select DATA MONITOR. Start engine and let it idle for at least 10 seconds. If idle speed is more than 1100 RPM, depress brake pedal and shift A/T into Drive, or M/T into 3rd or 4th gear. If first trip DTC is set, perform DIAGNOSTIC PROCEDURE.
DTC Confirmation Test "C"
Malfunction "C" is detected when ECM receives a low voltage from TP sensor under heavy -load driving conditions. Possible causes are:
"Â TP sensor circuit open or shorted.
"Â Intake air leaks.
"Â Defective TP sensor.
CAUTION: DO NOT use ECM ground terminals when measuring voltage.
To set DTC, start engine and warm to normal operating temperature. Measure voltage between ground and ECM connector terminal No. 61 (Green wire) by backprobing. Drive vehicle under a heavy -load condition with engine speed greater than 2000 RPM and voltage at terminal No. 61 greater than 3 volts for at least 10 consecutive seconds. If first trip DTC is detected, perform DIAGNOSTIC PROCEDURE.
Diagnostic Procedure
1. If malfunction "A" or "B" was duplicated, go to next step. If malfunction "C" was duplicated, adjust TP sensor. Check air intake duct and vacuum hoses for leaks or disconnection. Reconnect or repair as necessary and retest system. If no problems are found, go to next step.
2. Turn ignition off. Loosen and retighten engine ground bolts. Disconnect TP sensor harness connector. Turn ignition on. Measure voltage between ground and TP sensor harness connector terminal No. 3 (Red wire). If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, repair open or short in Red wire between TP sensor
and ECM and retest system.
3. Turn ignition off. Check continuity between ground and TP sensor harness connector terminal No. 1 (Black wire). Continuity should exist. Also, check circuit for short to voltage. Repair circuit as necessary and retest system. If problem does not exist, go to next step.
4. Turn ignition off. Disconnect ECM harness connector. Check continuity of Yellow wire between ECM harness connector terminal No. 92 and TP sensor harness connector terminal No. 2. Continuity should exist. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
CAUTION: DO NOT use ECM ground terminals when measuring voltage.
5. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Stop engine and turn ignition on. Disconnect vacuum hose from throttle opener. Connect a hand-held vacuum pump to throttle opener vacuum port. Apply 11.81 in. Hg. Measure voltage between ground and ECM terminal No. 92 (Yellow wire) by backprobing, with throttle in specified positions. See THROTTLE POSITION (TP) SENSOR VOLTAGE table. If voltage is not as specified, go to next step. If voltage is as specified, go to step 7.
6. Adjust closed throttle position switch. Repeat
step 5. If voltage is now as specified, go to next step. If voltage is still not as specified, replace TP sensor and retest system.
7. If malfunction "A" or "C" was duplicated, go to step 12. If malfunction "B" was duplicated, go to next step.
8. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminal No. 61 (Green wire), with engine at specified speeds. See MASS AIRFLOW SENSOR VOLTAGE table under DTC P0100: MASS AIRFLOW (MAF) SENSOR. Go to next step.
9. If voltage is as specified, go to next step. If voltage is not as specified, disconnect and reconnect MAF sensor harness connector and repeat step 8. If voltage is still not as specified, replace MAF sensor and retest system. If voltage is now as specified, go to next step.
CAUTION: DO NOT use ECM ground terminals when measuring voltage.
10. Ensure engine is at normal operating temperature. On models with NVIS, measure voltage
between ground and ECM terminals No. 66 and 75 (both Red wires) by backprobing. On models without NVIS, measure voltage between ground and ECM terminals No. 76 and 85 (both Red wires) by backprobing. On all models, see PIN VOLTAGE CHARTS article for specifications. If voltages or waveforms are as specified, go to next step. If voltages or waveforms are not as specified, replace camshaft position sensor and retest system.
11. Turn ignition off. Disconnect fuel injector harness connector. Measure resistance between fuel injector terminals (component side). Resistance should be 13.5 - 17.5 ohms at 68 °F (20 ° C). If resistance is as specified, go to next step. If resistance is not as specified, replace defective fuel injector(s) as necessary and retest system.
12. No problem is indicated at this time. Problem may be intermittent. THROTTLE POSITION (TP) SENSOR VOLTAGE
Throttle Position Volts
Fully Closed.15 -. 85
Between Fully Closed & Fully Open.15 -. 85 To 3.5 -4.7
Fully Open 3.5 -4.7
Thursday, January 7th, 2021 AT 1:05 PM
(Merged)