P0721-OUTPUT SPEED SENSOR CIRCUIT PERFORMANCE
For a complete wiring diagram Refer to Section 8W.
Theory of Operation
The transmission system uses two speed sensors. One is used to measure input rpm (primary pulley) and one to measure output rpm (secondary pulley).
The Input Speed sensor detects the primary pulley rpm by the use of a three-wire magnetic pickup device that generates a square wave signal as rotation occurs and is monitored by the Transmission Control Module (TCM). These inputs are essential for proper transmission operation.
- When Monitored:
Ignition on, engine running with the transmission in a valid forward gear.
System voltage between 9.0 and 16+.0 volts.
Vehicle speed greater than 10 Km/h (6 mph).
Accelerator Pedal Position (APP) greater than 12.5%.
Engine rpm greater than 450 rpm with TCC lock-up enabled.
No active DTCs from the following:
- Torque Convertor Clutch (TCC)
- Lock-up Solenoid
- CAN Bus
- Step Motor
- Input or Output Speed Sensor No Signal
- Transmission Range Sensor (TRS)
- Sensor Ground
- Set Condition:
All the below conditions must be present for the period of 5 seconds for the DTC to set:
- Engine speed minus the primary speed is less than 1000 rpm.
- Secondary speed multiplied by the estimated ratio, minus the Primary speed is greater than 1000 rpm.
- Vehicle speed minus the Vehicle speed calculated using the Secondary speed, is greater than or equal to 20 Km/h (12.5 mph)
| Possible Causes |
| ENGINE CAM OR CRANK DTCS PRESENT |
| DIRTY OR DAMAGED OUTPUT SPEED SENSOR |
| (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT HIGH RESISTANCE |
| (T52) OUTPUT SPEED SENSOR SIGNAL CIRCUIT HIGH RESISTANCE |
| (T52) OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE |
| (T130) OUTPUT SPEED SENSOR GROUND CIRCUIT HIGH RESISTANCE |
| (T130) OUTPUT SPEED SENSOR GROUND CIRCUIT SHORT TO VOLTAGE |
| OUTPUT SPEED SENSOR |
| TORQUE CONVERTER CLUTCH |
| TRANSMISSION CONTROL MODULE |
Always perform the CVT Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
Diagnostic Test
1. CHECK TO SEE IF THE DTC IS ACTIVEWith the scan tool, read Transmission DTCs.
Is the status Active for this DTC or is the STARTS SINCE SET counter 2 or less?
Yes
- Go To 2
No
- Go To 11
2. CHECK FOR ENGINE CAM OR CRANK SENSOR DTCS
With the scan tool, check engine DTCs.
Are there any Engine Cam or Crank sensor DTCs present?
Yes
- Refer to the engine category and perform the appropriate symptom(s).
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 3
3. CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT FOR AN OPEN (HIGH RESISTANCE)
Disconnect the Output Speed Sensor harness connector.
Ignition on, engine not running
With the scan tool under TIPM, actuate the Transmission.
Using a 12-volt test light connected to ground, check the (T16) Transmission Control Output circuit at the Output Speed Sensor harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly?
Yes
- Go To 4
No
- Repair the (T16) Transmission Control Output circuit for an open or high resistance.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
4. CHECK THE (T52) OUTPUT SPEED SENSOR SIGNAL CIRCUIT
With the scan tool under TIPM, stop the Transmission actuator.
Turn the ignition off, wait 5 seconds, then turn the ignition on.
Measure the voltage of the (T52) Output Speed Sensor Signal circuit.
Pick the answer that best matches your findings:
Voltage above 9.0 volts
- Go To 5
Voltage below 9.0 volts
- Go To 6
5. CHECK THE (T52) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Ignition on, engine not running
Measure the voltage of the (T52) Output Speed Sensor Signal circuit.
Is the voltage above 0.2 volts?
Yes
- Repair the (T52) Output Speed Sensor Signal circuit for a short to voltage.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. Check for any Service Bulletins for possible causes that may apply. If no problems are found, replace the TCM per the Service Information.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
6. CHECK THE (T52) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR AN OPEN (HIGH RESISTANCE)
Turn the ignition off to the lock position.
Disconnect the TCM C2 harness connector.
Connect a jumper wire between the (T52) Output Speed Sensor Signal circuit and B(+) in the Output Speed Sensor harness connector.
Using a 12-volt test light connected to ground, check the (T52) Output Speed Sensor Signal circuit in the TCM C2 harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly?
Yes
- Go To 7
No
- Repair the (T52) Output Speed Sensor Signal circuit for an open or high resistance.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
7. CHECK THE (T130) OUTPUT SPEED SENSOR GROUND CIRCUIT SHORT TO VOLTAGE
Turn the ignition off to the lock position.
Disconnect the jumper wire.
Disconnect the TCM C2 harness connector.
Ignition on, engine not running
Measure the voltage of the (T130) Output Speed Sensor Ground circuit.
Is the volage above 0.2 volts?
Yes
- Repair the (T130) Output Speed Sensor Ground circuit for a short to voltage
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 8
8. CHECK THE (T130) OUTPUT SPEED SENSOR GROUND CIRCUIT FOR AN OPEN (HIGH RESISTANCE)
Turn the ignition off to the lock position.
Connect a jumper wire between the (T130) Output Speed Sensor Ground circuit in the Output Speed Sensor harness connector and B(+).
Using a 12-volt test light connected to ground, check the (T130) Output Speed Sensor Ground circuit in the TCM C2 harness connector.
Does the test light illuminate brightly?
Yes
- Go To 9
No
- Repair the (T130) Output Speed Sensor Ground circuit for an open or high resistance.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
9. CHECK THE OUTPUT SPEED SENSOR
Turn the ignition off to the lock position.
Remove the Output Speed Sensor per the Service Information.
Check the Output Speed Sensor for any debris buildup or damage.
Did the Output Speed Sensor show any signs of debris buildup or damage?
Yes
- If there is a debris build up, clean the Output Speed Sensor as necessary and reinstall. If damaged or questionable in condition, replace the Output Speed Sensor.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Go To 10
10. REPLACE SPEED SENSOR AND TEST DRIVE VEHICLE
Turn the ignition off to the lock position.
Replace the Output Speed Sensor per the Service Information
Reconnect all previously disconnected harness connectors.
Ignition on, engine not running
With the scan tool, erase all Transmission DTCs.
Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
NOTE: Test drive the vehicle to speeds that will allow Torque Converter lock-up.
With the scan tool, read Transmission DTCs.
Does the DTC P0721 reset?
Yes
- Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. Check for any Service Bulletins for possible causes that may apply. If no problems are found, replace the TCM per the Service Information.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Test Complete.
11. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wires while checking for shorted and open circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform CVT VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)
No
- Test Complete.