P0720

P0720-OUTPUT SPEED SENSOR CIRCUIT





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Output Speed sensor is used to determine gear position by applying the signal to a static shift schedule map. The Output Speed sensor is also used together with Input Speed sensor to calculate gear ratios. The Transmission Control Module (TCM) compares Output shaft speed to Vehicle speed buss messages to diagnosis the system. If the TCM detects a fault with the Output speed signal, it switches to vehicle speed to determine gear position.

- When Monitored:
No solenoid or TRS DTCs set.

The calculated Output Speed based on Input Speed is greater than 250 rpm.

Transmission Range in Drive.

Engine Speed is greater than 300 rpm.

Transmission is not currently in a gear change.

- Set Condition:
500 consecutive tests without Output Speed sensor pulses.





Always perform the AW60T Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK IF THE DTC IS CURRENT
1. Using the scan tool, read TCM DTCs.
2. Record the Environmental Data and any DTCs.
3. Clear DTCs.
4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.

NOTE: It may be necessary to road test the vehicle to duplicate the original set conditions.

5. Read TCM DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Go To 4

2. CHECK THE INTERNAL OUTPUT SPEED SENSOR




1. Turn the ignition off to the lock position.
2. Disconnect TCM harness connector and remove the TCM from the transmission.
3. Measure the resistance of the internal Output Speed sensor between the appropriate terminals of the TCM transmission connector.

Is the resistance 602k Ohms (± 12k Ohms)?

Yes

- Go To 3

No

- Replace the internal Output Speed sensor.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

3. CHECK THE INTERNAL OUTPUT SPEED SENSOR FOR A SHORT TO GROUND




1. Measure the resistance of the internal Output Speed Sensor between ground the appropriate terminals of the TCM transmission connector.

Is the resistance below 100k Ohms?

Yes

- Remove the Transmission Side cover and inspect the internal harness for short to ground. Service and Repair. If no short is found, replace the Output Speed senor.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

No

- Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the TCM. AW60T TCM Programming Procedure.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

4. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Use the Freeze Frame Data to help duplicate the conditions in which the DTC originally set. Pay particular attention to the DTC set conditions, such as, VSS, MAP, ECT, and Load
3. Using the schematics as a guide, visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires.
4. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.
5. Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
6. Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

No

- Test Complete.