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Heavy Duty L96




DTC P1516, P2101, P2119, or P2176 (Heavy Duty L96)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P1516
- Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance

DTC P2101
- Throttle Actuator Position Performance

DTC P2119
- Throttle Closed Position Performance

DTC P2176
- Minimum Throttle Position Not Learned

Diagnostic Fault Information





Circuit/System Description

The engine control module (ECM) controls the throttle valve by applying a varying voltage to the control circuits of the throttle actuator control (TAC) motor. The ECM monitors the duty cycle that is required to actuate the throttle valve. The ECM monitors the throttle position (TP) sensors 1 and 2 to determine the actual throttle valve position.

Conditions for Running the DTC

P1516
* The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
* DTC P1516 runs continuously when the above conditions are met.

P2101
* DTC P0606 and P1682 is not set.
* The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
* The engine is running or the following conditions are met:

- The engine is not running.
- The ignition voltage is greater than 11 V.
- The TAC system is not in the Battery Saver mode.
- The ECM is commanding the throttle.
- The ECM has learned the minimum throttle position.

* DTC P2101 runs continuously when the above conditions are met.

P2119
* DTCs P0121, P0122, P0123, P0222, P0223, P06A3, or P1682 is not set.
* The ignition is ON.
* The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
* The TP sensor 1 voltage is greater than 1.7 V
* The TP sensor 2 voltage is greater than 1.8 V
* The ECM is not commanding the throttle blade.
* DTC P2119 runs continuously when the above conditions are met.

P2176
* The ignition is ON.
* The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
* The ECM enables the minimum throttle learn procedure.
* DTC P2176 runs continuously when the above conditions are met.

Conditions for Setting the DTC

P1516

The actual throttle position does not match the predicted throttle position for greater than 1 s.

P2101

The actual throttle position does not match the predicted throttle position for greater than 1 s.

P2119

The ECM detects that the throttle blade did not return to the default position when the TAC motor is de-energized for greater than 1 s.

P2176

The ECM detects that both throttle position (TP) sensors were greater than a predetermined voltage during the minimum throttle learn procedure for greater than 2 s.

Action Taken When the DTC Sets

P1516, P2101, and P2176
* DTCs P1516, P2101, and P2176 are Type A DTCs.
* The control module commands the TAC system to operate in the Reduced Engine Power mode.
* A message center or an indicator displays Reduced Engine Power.
* Under certain conditions, the control module commands the engine OFF.

P2119
* DTC P2119 is a Type C DTC.
* The driver information center, if equipped, may display a message.

Conditions for Clearing the MIL/DTC

* DTCs P1516, P2101, and P2176 are Type A DTCs.
* DTC P2119 is a Type C DTC.

Diagnostic Aids

* Inspect for a condition in which the throttle valve may have been held open. For example, ice may have formed in the throttle bore causing the throttle valve not to close.
* A high resistance condition on the throttle position and throttle actuator control circuits could cause a DTC to set.
* A low battery condition may cause a DTC to set.

Reference Information
Schematic Reference

Engine Controls Schematics (except L96) ([1][2]Electrical Diagrams)Engine Controls Schematics (L96) ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Throttle Actuator Control (TAC) System Description (Throttle Actuator Control (TAC) System Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Verification

Note: A low battery voltage or charging system condition may cause a DTC to set.

1. Ignition ON, observe the DTC information with a scan tool. DTC P0121, P0122, P0123, P0222, P0223, P0562, P0621, P0622, or P2135 should not set.

• If a DTC sets, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.

2. Clear the DTCs with a scan tool. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.
3. Ignition ON, observe the scan tool TAC Motor parameter. The reading should display Enabled.
4. Observe the DTC information with a scan tool. DTC P1516, P2101, P2119, or P2176 should not set.

Note: If there is a condition with the throttle body, the TAC Motor Command parameter will go to 99 % for a predetermined amount of time and then a DTC sets. Once a DTC is set, the TAC Motor Command parameter will go to 0 % and the TAC Motor parameter will display Disabled.

5. Perform the Throttle Sweep Test while observing the TAC Motor parameter with a scan tool. The TAC Motor parameter should display Enabled while the Throttle Sweep Test is in progress.

Note: Before replacing the throttle body assembly, make sure the throttle control circuits are not shorted to B+.

• If not the specified value, replace the throttle body assembly.

6. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Warning

Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.

1. Ignition OFF, verify the following conditions do not exist with the throttle body assembly:

* A throttle blade that is not in the rest position
* A throttle blade that is binding open or closed
* A throttle blade that is free to move open or closed without spring pressure

• If a condition is found, replace the throttle body assembly.

Note: Disconnecting the throttle body harness connector may cause additional DTCs to set.

2. Ignition OFF, disconnect the harness connector at the throttle body assembly.
3. Ignition ON, verify that a test lamp does not illuminate between each control circuit listed below and ground.

* TAC Motor Control Closed circuit terminal A
* TAC Motor Control Open circuit terminal B

• If test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Ignition ON, verify that a test lamp does not illuminate between each control circuit listed below and B+.

* TAC Motor Control Closed circuit terminal A
* TAC Motor Control Open circuit terminal B

• If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

5. Ignition OFF, set the DMM to the 40 V scale, select the Min/Max Recording Mode, and set the Peak Min/Max response time to 1 ms.

Note:
* The DMM Min/Max Recording Mode and the response time of 1 ms must be reset after testing each circuit or a lower voltage will be recorded.
* The ignition must be OFF and the ECM completely powered down before testing each circuit or a lower voltage will be recorded.

6. Ignition OFF, measure the voltage using the DMM Min/Max Recording Mode function on each circuit listed below as the ignition is turned ON. The Max voltage should be within 1 V of B+.

* TAC Motor Control Closed circuit terminal A
* TAC Motor Control Open circuit terminal B

• If not within the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

7. If all circuits and connections test normal, replace the throttle body assembly.

Repair Instructions

* Throttle Body Assembly Replacement (Removal and Replacement)
* Control Module References (Control Module References) for Engine Control Module replacement, programming, and setup

Repair Verification

1. Install any components that have been removed or replaced during diagnosis.
2. Perform any adjustments, programming or setup procedures that are required when a component is removed or replaced.
3. Clear the DTCs with a scan tool.
4. Turn OFF the ignition for 60 s.
5. Perform the Throttle Sweep Test while observing the TAC Motor parameter with a scan tool. The TAC Motor parameter should display Enabled while the Throttle Sweep Test is in progress.

• If Disabled is displayed, a condition still exists.

6. If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) and perform the appropriate diagnostic procedure.

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