DTC P0721-P0723, P077C, P077D, P172A, or P172B

Automatic Transmission - 10L80 MHS MQC | Diagnostic Information and Procedures | Document ID: 5224463 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P0721 Output Shaft Speed Sensor Performance DTC P0722 Output Shaft Speed Sensor Circuit No Signal DTC P0723 Output Shaft Speed Sensor Circuit Intermittent DTC P077C Output Shaft Speed Sensor Circuit Low DTC P077D Output Shaft Speed Sensor Circuit High DTC P172A Output Shaft Speed Sensor Direction Not Plausible - Forward DTC P172B Output Shaft Speed Sensor Direction Not Plausible - Reverse Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performanc
9 V Reference	P077C**	P077C**	P077D	P0721, P0722, P0723, P172A, P172B
Signal	P077C	P077C	P077D *	P0721, P0722, P0723, P172A, P172B
* Internal control module or component damage may occur if the circuit shorts to B+. ** Additional DTCs may set

Typical Scan Tool Data Output Shaft Speed Sensor Short to Short to Circuit Ground Open Voltage Operating Conditions: Engine = Running

Circuit	Short to Ground	Open	Short to Voltage
Parameter Normal Range: 500 to 7,500 RPM
Signal	0 RPM	0 RPM	0 RPM

Sensor Supply Circuit Status

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition = On Parameter Normal Range: Okay
9 V Reference	Malfunction	Okay	Malfunction

Circuit/System Description For an overview of the component/system, refer to: Electronic Component Description

Circuit	Description
9 V Reference	Regulated voltage supplied by the control module.
Signal	The sensor produces a frequency modulated signal.

	Component	Description
	B14A Automatic Transmission Output Speed Sensor	The sensor contains a hall-effect sensor and additional electronics that processes the signal. It detects the change of strength of the magnetic field caused by the reluctor ring. When the strength changes, the sensor changes the amount of current it consumes. This results in a square wave signal of current and voltage. The control module detects the frequency in which the signal changes, which is proportional to the rotational speed.
	K71 Transmission Control Module	The control module contains a microprocessor used to process input data to control outputs. The control module receives information from a variety of sensors, switches and serial data information from other control modules. This information is used to control a combination of solenoid valves to obtain the correct line pressure, gear ratio and torque converter clutch operation.
	Reluctor Ring	The reluctor ring has 68 teeth, magnetic segments, or indentations.

Component	Description
	The reluctor ring is part of the component: Output Shaft Assembly

The sensor is an input to the control module K71. The input signal is used to determine the rotational speed of the component: Output Shaft Assembly Conditions for Running the DTC P0721, P172A, P172B { P077C, P077D } Engine Speed = Greater than 499 RPM Battery Voltage = Greater than 9 V Ignition and Start Signal = 9 to 32 V Ignition and Start Switch Signal = On { P077C, P077D } Transmission Service Fast Learn = Disabled Frequency the DTC runs = Continuously — After the running conditions are met P0722, P0723 { P0722 } DTC P0723, P077C, P077D = Not set DTCs related to the following system/component = Not Set – B14A Automatic Transmission Output Speed Sensor – B65 Manifold Absolute Pressure and Intake Air Temperature Sensor – B75 Mass Airflow Sensor – B107 Accelerator Pedal Position Sensor – Q14 Exhaust Gas Recirculation Valve – Q17 Fuel Injector – Engine Misfire – Fuel Trim System { P0722 } Accelerator Pedal Position Sensor = Greater than 3% Battery Voltage = Greater than 9 V { P0722 } Engine Torque = Greater than 30 Nm (22 lb ft) Ignition and Start Signal = 9 to 32 V Ignition and Start Switch Signal = On Frequency the DTC runs = Continuously — After the running conditions are met P077C, P077D { P077C } DTC P077D = Not set { P077D } DTC P077C = Not set Battery Voltage = Greater than 10 V Ignition and Start Signal = 9 to 32 V Ignition and Start Switch Signal = On Transmission Service Fast Learn = Disabled Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P0721 Output Speed Sensor Direction Signal = Not Plausible — For greater than 3.5 s P0722 Output Speed Sensor = Less than 31 RPM — For greater than 4 s P0723 Output Speed Sensor = Decreases greater than 649 RPM — For greater than 7.5 s P077C Output Speed Sensor = Less than 0.25 V / Short to Ground — For greater than 1 s P077D Output Speed Sensor = Greater than 4.75 V / Short to Voltage — For greater than 1 s P172A Current Gear = Forward Gear & Output Shaft Speed Sensor Direction ≠ Forward — For greater than 2.5 s P172B Current Gear = Reverse Gear & Output Shaft Speed Sensor Direction ≠ Reverse — For greater than 2.5 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC Autostart/Autostop = Disabled — If equipped Grade braking = Disabled Manual Shift Control = Disabled Neutral Idle Mode = Disabled Powertrain braking = Disabled Tap Up & Tap Down = Disabled TCC Control = Disabled Transmission Adaptive Pressure Control = Freeze current adapt values Transmission gear allowed = Reverse or Gear 5 Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Reference Information Schematic Reference Automatic Transmission Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Special Tools EL-38522 Variable Signal Generator Circuit/System Verification

1. Ignition » On / Vehicle » In Service Mode
2. Verify the scan tool parameter: Sensor Supply 2 Circuit Status = Okay ⇒ If not the specified state Refer to: Circuit/System Testing ⇓ If the specified state

Caution

Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

3. Raise and support the vehicle.
4. Engine » Running
5. Transmission » D
6. Verify the scan tool parameter: Output Shaft Speed Sensor = The value should change smoothly and gradually as the vehicle speed is increased and decreased. ⇒ If the value does not change smoothly and gradually Refer to: Circuit/System Testing ⇓ If the value changes smoothly and gradually
7. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC is not set
8. All OK. Circuit/System Testing
9. Ignition/Vehicle & All vehicle systems » Off

Note

When the following connector is disconnected, the ignition cannot be turned off due to lack of a valid park input to the TCM. If the ignition needs to be turned off, the connector will need to be reconnected.

2. Disconnect the electrical connector: X1 @ T12 Automatic Transmission
3. Ignition » On / Vehicle » In Service Mode
4. Test for 8.3 to 9.6 V between the test points: 9 V Reference circuit terminal 7 & Ground ⇒ If less than 8.3 V 4.1. Ignition/Vehicle » Off 4.2. Disconnect the electrical connector: K71 Transmission Control Module 4.3. Test for infinite resistance between the test points: 9 V Reference circuit terminal 7 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 4.4. Test for less than 2 Ω between the test points: 9 V Reference circuit terminal 7 @ Component harness & Terminal 7 @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K71 Transmission Control Module ⇒ If greater than 9.6 V 4.1. Ignition/Vehicle » Off 4.2. Disconnect the electrical connector: K71 Transmission Control Module 4.3. Ignition » On / Vehicle » In Service Mode 4.4. Test for less than 1 V between the test points: 9 V Reference circuit terminal 7 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K71 Transmission Control Module ⇓ If between 8.3 and 9.6 V
5. Ignition/Vehicle » Off
6. Install » EL-38522 Variable Signal Generator Voltage » 5 V Frequency » 5 kHz Duty Cycle » 10% Black lead @ Battery Negative Post Red lead @ Signal circuit terminal 4
7. Ignition » On / Vehicle » In Service Mode
8. Verify the scan tool parameter: { 10L60 } Output Shaft Speed Sensor = 6,400 to 6,600 RPM { 10L80, 10L90 } Output Shaft Speed Sensor = 4,300 to 4,500 RPM ⇒ If not within specified range 8.1. Ignition/Vehicle » Off 8.2. Disconnect the electrical connector: K71 Transmission Control Module 8.3. Ignition » On / Vehicle » In Service Mode 8.4. Test for less than 1 V between the test points: Signal circuit terminal 4 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇓ If less than 1 V 8.5. Ignition/Vehicle » Off 8.6. Test for infinite resistance between the test points: Signal circuit terminal 4 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 8.7. Test for less than 2 Ω between the test points: Signal circuit terminal 4 @ Component harness & Terminal 14 @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K71 Transmission Control Module ⇓ If within the specified range
9. Verify the scan tool parameter: Output Speed Sensor Direction = Forward ⇒ If not the specified state Replace the component: K71 Transmission Control Module ⇓ If the specified state
10. Setup » EL-38522 Variable Signal Generator Voltage » 5 V Frequency » 600 Hz Duty Cycle » 10% Black lead @ Battery Negative Post Red lead @ Signal circuit terminal 4
11. Verify the scan tool parameter: Output Speed Sensor Direction = Reverse ⇒ If not the specified state Replace the component: K71 Transmission Control Module ⇓ If the specified state
12. Remove » EL-38522 Variable Signal Generator
13. Connect the electrical connector. X1 @ T12 Automatic Transmission
14. Ignition/Vehicle » Off
15. Remove the component: Automatic Transmission Fluid Pan
16. Disconnect the electrical connector: B14A Automatic Transmission Output Speed Sensor
17. Ignition » On / Vehicle » In Service Mode
18. Test for 8.3 to 9.6 V between the test points: 9 V Reference circuit terminal 2 & Ground ⇒ If not between 8.3 and 9.6 V Replace the component: Automatic Transmission Wiring Harness ⇓ If between 8.3 and 9.6 V
19. Ignition/Vehicle » Off
20. Install » EL-38522 Variable Signal Generator Voltage » 5 V Frequency » 5 kHz Duty Cycle » 10% Black lead @ Battery Negative Post Red lead @ Signal circuit terminal 1
21. Ignition » On / Vehicle » In Service Mode
22. Verify the scan tool parameter: { 10L60 } Output Shaft Speed Sensor = 6,400 to 6,600 RPM { 10L80, 10L90 } Output Shaft Speed Sensor = 4,300 to 4,500 RPM ⇒ If not within specified range Replace the component: Automatic Transmission Wiring Harness ⇓ If not within specified range
23. Test or replace the component: B14A Automatic Transmission Output Speed Sensor Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Q77 Transmission Control Solenoid Valve Characterization Programming Automatic Transmission Fluid, Fluid Pan and/or Filter Replacement Automatic Transmission Output Speed Sensor Replacement — B14A Automatic Transmission Output Speed Sensor Automatic Transmission Wiring Harness Replacement For control module replacement, programming, and setup refer to: Control Module References Additional Procedures Transmission Service Fast Learn Procedure — Perform only when the component/system is serviced.