PO720 - Output Speed Sensor Circuit Malfunction

Bernard's Blog: Dodge Transmission Output Speed Sensor

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Sep 8, 2009 - The code was straight forward - PO720 - Output Speed Sensor Circuit.... words but if you've never seen the underside of a 1999 Dodge Ram 1500 pickup ...My 99 Dodge 2500 Ram won't accelerate..transmission is NOT ... RR - If the engine revs but the vehicle doesn't speed up then the trans is slipping.

code po720 refers to output shaft speed sensor (OSS) --circuit malfunction ===causes---wiring---OSS sensor---TCM
code po771 refers to shift solenoid (SS0 E --performance stuck off===causes --wiring ---shift solenoid.

code p0720 refers to out put shaft speed (OSS) sensor-circuit malfunction===causes wiring OSS sensor --ECM/TCM
Having replace both sensors means that you still not have fixed the fault. Check the wiring and connectors for moisture an damaged pins and the TCM plays a big part in your problem ( transmission control module)

This is the Output shaft speed sensor. It is located on the tail of the transmission housing on 4x4 units.

P0720-OUTPUT SPEED SENSOR ERROR

WHEN MONITORED
The transmission gear ratio is monitored continuously while the transmission is in gear.

SET CONDITION
If there is an excessive change in output RPM in any gear. This DTC can take up to five minutes of problem identification before illuminating the M.I.L.

POSSIBLE CAUSES[*]Output speed sensor signal circuit open[*]Speed sensor ground circuit open[*]Output speed sensor signal circuit short to ground[*]Speed sensor ground circuit short to ground[*]Output speed sensor signal circuit short to voltage[*]Speed sensor ground circuit short to voltage[*]Output speed sensor[*Powertrain Control Module (PCM)[*]Intermittent wiring and connectorsi cen get you a full flow chart on how to check it out if you wish

p0733 Gear 3 Incorrect ratio

CODE PO720 - OUTPUT SPEED SENSOR MALFUNCTION / CODE PO732 - INCORRECT GEAR RATIO SECOND GEAR / CODE PO781 - FIRST TO SECOND SHIFT MALFUNCTION / CODE POP1247 - TURBOCHARGER BOOST PRESSURE LOW CONDITION. COULD NOT FIND CODE PO1316. LOOK ALL PROBLEMS COULD BECAUSED BY CODE PO720 FAULTY OUTPUT SPEED SENSOR IT CONTROLS TRANSMISSION SHIFTS.

PO7230 is a trouble code for (output speed sensor circuit malfunction) and the speed sensor is located on the extension housing of the transmission.

P1529 indicates that your TCM asked the ECM to turn on the check engine lamp.

The range switch and the output speed sensors are the items that are abnormally affecting the operation of the transmission. The diagnostic logic in your computer can distinguish these issues from one another, so you'll definitely want to do both. You have no diagnostic code for the input speed sensor (P0715) listed, so I have made no recommendation to replace it. In my opinion, it's not a labor-intensive repair, so I wouldn't recommend replacing it unless you have reason to believe it's bad.

DTC - P0720 (OUTPUT SHAFT SPEED SENSOR SYSTEM)
Code No. P0720 Output shaft speed sensor system
If the output from the output shaft speed sensor is continuously 50% lower than the vehicle speed for 1 second or more while driving in 3rd or 4th gear at a speed of 30 km/h or more, it is judged to be an open circuit or short-circuit in the output shaft speed sensor and diagnostic trouble code No. P0720 is output. If diagnostic trouble code No. P0720 is output four times, the transmission is locked into 3rd gear or 2rid gear as a fail-safe measure.
Probable cause
Malfunction of the output shaft speed sensor
Malfunction of the transfer drive gear or driven gear
Malfunction of connector
Malfunction of the TCM

DTC - P0715 (INPUT SHAFT SPEED SENSOR SYSTEM)
Code No. P0715 input shaft speed sensor system
If no output pulse is detected from the input shaft speed sensor for 1 second or more while driving in 3rd or 4th gear at a speed of 30 km/h (19 mph) or more, it is judged to be an open circuit or short-circuit in the input shaft speed sensor and diagnostic trouble code No. P0715 is output. If diagnostic trouble code P0715 is output four times, the transaxle is locked into 3rd gear or 2nd gear as a fail-safe measure.
Probable cause
Malfunction of the input shaft speed sensor
Malfunction of the underdrive clutch retainer
Malfunction of connector
Malfunction of the TCM

Is needed replace.

DTC = P0720
footnote b = MIL (malfunction indicator light) comes on after 2nd occurance
footnote c = tranny control indicator light (TCIL) flashes
circuit = OSS = output shaft speed sensor in the tranny (not the variable speed sensor (VSS) in the diff).
condition = OSS sensor circuit malfunction
probable causes = Short/open circuit, sensor, PCM

My guess? Replacing the OSS will take care of it. I hope you don't have a faulty PCM.

code po720 is the output speed sensor malfunction