Dodge Ram Truck 1500-2500-3500. Manual — part 1724
P0720-LOW OUTPUT SPEED SENSOR - RPM ABOVE 15 MPH (DIESEL) (CONTINUED)
For the Transmission circuit diagram (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - SCHE-
MATICS AND DIAGRAMS)
For a complete wiring diagramRefer to Section 8W
Theory of Operation
•
When Monitored:
Continuously with the ignition on, engine running, and gear selector NOT in park or neutral.
•
Set Condition:
This DTC will set if the vehicle speed (reported from the CAB module) is above 24 Kmh (15 mph), and the
monitored Output Shaft Speed is below 60 RPM for 2.6 seconds.
Possible Causes
PARK/NEUTRAL DTC PRESENT
(T13) SENSOR GROUND CIRCUIT OPEN
(T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT OPEN
(T13) SENSOR GROUND CIRCUIT SHORT TO ANOTHER CIRCUIT
(T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO GROUND
(T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO ANOTHER CIRCUIT
(T13) SENSOR GROUND CIRCUIT SHORT TO VOLTAGE
(T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
OUTPUT SPEED SENSOR
ENGINE CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Diagnostic Test
1.
CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Record the Freeze Frame data for the reported DTC.
With the scan tool, erase DTCs.
Turn the ignition off to the lock position.
Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.
NOTE: It may be necessary to road test the vehicle to duplicate the original set conditions.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Yes
>> Go To 2
No
>> Go To 11
21 - 828
AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS
DR/DH
P0720-LOW OUTPUT SPEED SENSOR - RPM ABOVE 15 MPH (DIESEL) (CONTINUED)
2.
CHECK IF A PARK/NEUTRAL DTC IS PRESENT
Is there a Park/Neutral DTC present?
Yes
>> Refer to the Transmission category and perform the appropriate symptom(s). (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
No
>> Go To 3
3.
CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the ECM C2 harness connector.
Disconnect the Output Speed Sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary
Measure the resistance of the (T14) Output Speed Sensor Signal cir-
cuit between the ECM C2 harness connector and the Output Speed
Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes
>> Go To 4
No
>> Repair the (T14) Output Speed Sensor Signal circuit for an
open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
4.
CHECK THE (T13) SENSOR GROUND CIRCUIT FOR AN OPEN
Measure the resistance of the (T13) Sensor Ground circuit between
the ECM C2 harness connector and the Output Speed Sensor harness
connector.
Is the resistance below 5.0 ohms?
Yes
>> Go To 5
No
>> Repair the (T13) Sensor Ground circuit for an open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
DR/DH
AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS
21 - 829
P0720-LOW OUTPUT SPEED SENSOR - RPM ABOVE 15 MPH (DIESEL) (CONTINUED)
5.
CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
Measure the resistance between ground and the (T14) Output Speed
Sensor Signal circuit.
Is the resistance greater than 100K ohms?
Yes
>> Go To 6
No
>> Repair the (T14) Output Speed Sensor Signal circuit for a
short to ground.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
6.
CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Measure the resistance between the (T14) Output Speed Sensor Sig-
nal circuit and all other circuits in the ECM C2 harness connector.
Is the resistance greater than 100K ohms between the (T14)
Output Speed Sensor Signal circuit and any other circuit(s) in
the ECM C2 harness connector?
Yes
>> Go To 7
No
>> Repair the (T14) Output Speed Sensor Signal circuit for a
short to another circuit(s).
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
21 - 830
AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS
DR/DH
P0720-LOW OUTPUT SPEED SENSOR - RPM ABOVE 15 MPH (DIESEL) (CONTINUED)
7.
CHECK THE (T13) SENSOR GROUND CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Measure the resistance between the (T13) Sensor Ground circuit and
all other circuits in the ECM C2 harness connector.
Is the resistance greater than 100K ohms?
Yes
>> Go To 8
No
>> Repair the (T13) Sensor Ground circuit for a short to
another circuit(s).
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
8.
CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
Ignition on, engine not running.
Measure the voltage of the (T14) Output Speed Sensor Signal circuit
in the Output Speed Sensor harness connector.
Is there any voltage present?
Yes
>> Repair the (T14) Output Speed Sensor Signal circuit for a
short to voltage.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No
>> Go To 9
9.
CHECK THE (T13) SENSOR GROUND CIRCUIT FOR A SHORT TO VOLTAGE
Measure the voltage of the (T13) Sensor Ground circuit in the Output
Speed Sensor harness connector.
Is there any voltage present?
Yes
>> Repair the (T13) Sensor Ground circuit for a short to volt-
age.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No
>> Go To 10
DR/DH
AUTOMATIC TRANSMISSION - 48RE - DIESEL - ELECTRICAL DIAGNOSTICS
21 - 831
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