Land Rover OBD-II Trouble Codes
-------------------------------------------------The diagnostic trouble codes (DTCs) P2105, P2106, P2111, and P2112 all relate to issues with the Throttle Actuator Control (TAC) system, indicating problems with the throttle actuator. Here's a breakdown of each code:
Electronic Throttle Processor Error,
TAC Module Performance Fault,
PCM Internal Throttle Logic,
Drive-By-Wire System Shutdown,
Actuator Control Feedback Error,
Diagnostic Overview
The System: These codes relate to the Throttle Actuator Control (TAC) system. In many modern vehicles, the TAC logic is a dedicated "micro-processor" inside the main Engine Control Module (PCM/ECM) that handles the high-speed movements of the throttle blade.
P2107 (Processor Fault): This is an internal self-test failure. The PCM has detected that its own internal processor responsible for throttle control is not calculating data correctly.
P2108 (Performance Fault): The PCM sees that the throttle motor is not responding to commands as quickly or as accurately as the programmed software expects.
Common Failure Points
Low Battery Voltage: This is the #1 "ghost" cause. If the battery is weak or the alternator is failing, the sudden high-current draw required to move the throttle motor can cause the PCM processor to "glitch" and throw a P2107.
Throttle Body Obstruction: Heavy carbon buildup or a physical object can jam the butterfly valve. If the motor tries to move the valve and hits resistance, it triggers the P2108 performance code.
Internal PCM Damage: Since P2107 specifically mentions the "processor," it can sometimes indicate that the PCM itself has suffered an internal hardware failure, often due to a short circuit in the wiring harness.
Wiring Harness Interference: High-voltage "noise" from failing spark plug wires or a bad alternator diode can interfere with the sensitive data signals between the pedal and the PCM.
Troubleshooting Steps
Hard Reset: Disconnect the negative battery terminal for 30 minutes. This can sometimes clear a "logic freeze" in the PCM processor.
Inspect the Connector: Unplug the throttle body and look for Terminal Fretting. Tiny vibrations can cause the metal pins to wear down, leading to intermittent data loss.
The "Snap" Test: With the intake boot removed and the engine off, gently push the throttle blade with your finger. It should move smoothly and "snap" back to a slightly open position via spring tension. If it feels "crunchy" or sticks, the unit is bad.
Check Grounds: Ensure the main engine-to-chassis ground strap is clean and tight. Poor grounding is a major cause of processor communication errors.
Would you like me to find the specific "Throttle Body Relearn" steps for your vehicle, which is often required after fixing these codes?
How to Diagnose P2107 and P2108 Throttle Codes
This video explains how to differentiate between a mechanical throttle body failure and a software/electronic issue within the PCM's actuator control module.
1. **P2105 - Throttle Actuator Control System - Forced Engine Shutdown:**
- This code indicates that the Throttle Actuator Control (TAC) system has forced an engine shutdown.
2. **P2106 - Throttle Actuator Control System - Forced Limited Power:**
- P2106 suggests that the TAC system has forced the engine into a limited power mode.
3. **P2111 - Throttle Actuator Control System - Stuck Open:**
- Indicates that the TAC system has detected a problem where the throttle actuator is stuck in the open position.
4. **P2112 - Throttle Actuator Control System - Stuck Closed:**
- P2112 points to a situation where the TAC system has identified a problem with the throttle actuator being stuck in the closed position.
### Possible Causes:
1. **Faulty Throttle Actuator Control Motor:** Issues with the motor responsible for controlling the throttle.
2. **Wiring Issues:** Problems with the wiring or connectors associated with the Throttle Actuator Control system.
3. **Throttle Position Sensor Issues:** Malfunctioning throttle position sensor affecting the TAC system.
4. **Faulty Throttle Body:** Problems within the throttle body itself that impact TAC system operation.
5. **Connector Problems:** Faulty connectors or terminal issues in the wiring harness related to the TAC system.
6. **Mechanical Obstruction:** Physical obstructions or issues within the throttle body preventing proper movement.
7. **Electronic Control Module (ECM) Issues:** Problems with the ECM responsible for managing the TAC system.
### Diagnostic Steps:
1. **Inspect Throttle Actuator Control Motor:** Check the Throttle Actuator Control motor for signs of damage or wear. If it appears faulty, consider replacement.
2. **Check Wiring and Connectors:** Inspect the wiring and connectors associated with the Throttle Actuator Control system. Look for any signs of damage, corrosion, or loose connections.
3. **Test Throttle Position Sensor:** Check the throttle position sensor for proper operation. Replace if necessary.
4. **Verify Throttle Body Functionality:** Ensure that the throttle body is mechanically sound and functioning correctly.
5. **Perform Continuity Tests:** Check for continuity in the wiring from the Throttle Actuator Control motor to the ECM.
6. **Check for Short or Open Circuits:** Look for short circuits or open circuits in the Throttle Actuator Control system wiring.
7. **Verify Throttle Body Movement:** Ensure that the throttle body can move freely and is not mechanically obstructed.
8. **Verify ECM Operation:** Test the ECM for proper operation. Replace if necessary.
9. **Clear Codes:** After addressing any identified issues, clear the trouble codes and monitor the system for recurrence.
10. **Consider Professional Assistance:** If you are unsure about diagnosing or addressing these issues yourself, or if the faults persist, it's advisable to consult with a qualified mechanic or technician.
These codes indicate critical issues with the Throttle Actuator Control system, potentially leading to forced engine shutdown or limited power. Addressing the root cause is crucial for proper engine performance and safety. If in doubt or if the faults persist, seeking professional assistance is recommended for a thorough diagnosis and effective repair.
