not sure what the po721 code is. I know the 720 is the oss sensor that i already replaced shifting eratic not sure what gear it wants to be in can anyone help thanks

 

P0721 Output Speed Sensor Range/Performance

 

so its the same as the 720 any ideas on the problem

 

I dont have a clue but I am sure some of the pros will be by to lend a hand..

 

thanx anyway nolan

 

Heres a bump for ya someone will be by...

 

could it be rfi noise from the fuel pump or alt. If so any way to check them

 

Did you clean/replace the one in the diff too? I can never remember which sensor is which...

 

P0721 OSS Noisy OSS Erratic signal, sensor, intermittent circuit

Edit: may be the plug or wiring?

 

checked wiring did nt see anny bad spots in wire cleaned connector plugs still doing it replaced sensor in diff also still giving me the code od light blinks as soon as its shifts the first time

 

Here is the diagnostic flow chart for these codes (taken fro my Ford dvd manual) I just copied and pasted, so illustrations are not included.


PINPOINT TEST F: TURBINE SHAFT SPEED (TSS) AND OUTPUT SHAFT SPEED (OSS) SENSORS
CONDITIONS DETAILS/RESULTS/ACTIONS
NOTE: Refer to the Output Shaft Speed (OSS) Sensor Connector illustration preceding these pinpoint tests.
F1 ELECTRONIC DIAGNOSTICS
Check to make sure the transmission harness connector is fully seated, terminals are fully engaged in connector and in good condition before proceeding.






Diagnostic Data Link



PCM

Select PID/Data Monitor and Record.
Select the following PIDs: TSS, OSS.


Does vehicle enter PID/Data Monitor and Record?
Yes
REMAIN in PID/Data. GO to F2 .

No
REPEAT procedure to ENTER PID. If vehicle did not enter PID, REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual for diagnosis of PCM.
F2 DRIVE CYCLE TEST
While monitoring the appropriate sensor PID, drive the vehicle so that the transmission upshifts and downshifts through all gears.


Does the TSS, or OSS Speed PID increase and decrease with engine and vehicle speed or is the sensor signal erratic (drop to zero or near zero and return to normal operation)?
Yes
If the TSS or OSS Speed PID increase and decrease with engine and vehicle speed, CLEAR all DTCs. ROAD TEST to verify if concern is still present. If concern is still present, REFER to Diagnosis By Symptom in this section for diagnosis.

If the sensor signal is erratic, INSPECT for intermittent concern in the internal/external harness, sensor or connector.

No
If the TSS, or OSS Speed PID does not increase and decrease with engine and vehicle speed, INSPECT for open or short in vehicle harness, sensor, a PCM concern, or internal hardware concern.

If the sensor signal is steady, GO to F3 .
F3 CHECK RESISTANCE OF TSS OR OSS SENSOR
Disconnect the appropriate vehicle harness connector from the TSS and or OSS sensor.

For TSS or OSS: Measure the resistance between pin 1 and pin 2 at the sensor.
Record the resistance. Resistance should be as follows:
Sensor Resistance (ohms)
TSS — PTO Only Applications 496-1,244
TSS — Non-PTO Applications 781-1,979
OSS — All Applications 781-1,979



Is the resistance within specification for the appropriate sensor?
Yes
REFER to Diagnosis By Symptom in this section for concern diagnosis.

No
For TSS and OSS, INSTALL a new sensor.