Here is the instruction show you guide on how to repair Allison 3000 and 4000 Gen5 transmission P0720 Output shaft speed sensor circuit.
Related Contents:
Allison DOC GEN5 Diagnostic Software 2025.02
NEXIQ USB Link 3 Diagnostic Tool
DIAGNOSTIC RESPONSE:
DNS, Lock in current range
CIRCUIT DESCRIPTION:
The speed sensors are devices which convert mechanical motion to an electrical signal. This test detects an output speed sensor circuit short to battery, ground, or open.
ACTION TAKEN WHEN THE DTC SETS:
When DTC P0720 is active, the following conditions occur:
1 If the DTC sets while shift not in process, remains in current range.
2 If the DTC sets while shift is in process, complete shift and lock in that range.
3 There is no response to shift selector requests.
4 DTC is stored in TCM history.
5 The CHECK TRANS light illuminates.
6 The TCM inhibits TCC engagement.
7 The TCM freezes shift adapts.
CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tol to clear the DTC from the TCM history.The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.
DIAGNOSTIC AIDS:
DTC P0720 may be caused by:
1 W140 and/or W160 shorted to another wire in chassis harness or to ground.
2 W140 and/or W160 high resistance or open circuit.
3 Broken or defective connector assemblies allowing pushed back pins to short together.
4Unlocked connectors, missing seal plugs allowing moisture in connectors.
5 Fatigued wires at speed sensor connectors (broken strands).
6 Incorrect pin crimps or expanded terminals.
7 Defective output shaft speed sensor.
8 Defective TCM.
9 Wire pair not twisted or not sufficiently twisted.
NOTE:Confirm that the sped sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300mm.These twists must extend the entire length of the wiring harness to within at least 50mmof the speed sensor connector.
NOTE:
The OEM Transmission warranty, or the extended cover and mission specifications.
Review applicable information in CONTROL SYSTEM AND TRANSMISSION SPECIFICATIONS to find additional connector diagrams, and troubleshooting tips.
