P2112-ELECTRONIC THROTTLE CONTROL - UNABLE TO OPEN
For a complete wiring diagram, refer to the Wiring Information.
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Thoery of operation
The Electronic Throttle Control (ETC) system uses two Accelerator Pedal Position (APP) Sensors to monitor the accelerator pedal position. The APP Sensors 1 and 2 are located within the pedal assembly. Each sensor has a 5-Volt reference circuit, a low reference circuit and a signal circuit. Processors are also used to monitor the ETC system data. The processors are located within the Powertrain Control Module (PCM). Each signal circuit provides processors with a signal voltage proportional to pedal movement. The processors share and monitor data to verify that the indicated APP calculation is correct.
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When Monitored:
Ignition on and battery voltage greater than 10.0 Volts.
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Set Condition:
Just after key on, the throttle is opened and closed to test the system. If the TP Sensor does not return to Limp Position at the end of this test, this DTC will set. One trip fault and the code will set within five seconds. ETC light is flashing.
Possible Causes |
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| THROTTLE PLATE STUCK AT OR BELOW LIMP HOME POSITION |
| (K126) ETC NEGATIVE CIRCUIT SHORTED TO VOLTAGE |
| (K124) ETC POSITIVE CIRCUIT OPEN |
| (K126) ETC NEGATIVE CIRCUIT OPEN |
| (K124) ETC POSITIVE CIRCUIT SHORTED TO GROUND |
| (K126) ETC NEGATIVE CIRCUIT SHORTED TO GROUND |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
1. ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
| 1. | Ignition on, engine not running. |
| NOTE: | The PCM tests the ETC Motor by opening and closing the Throttle Plate before starting the engine. If during this test the throttle plate does not return to the closed position this DTC sets. |
| 2. | With the scan tool, read the active DTCs. |
| NOTE: | Diagnose any TP Sensor, Battery voltage and 5 Volt Supply DTCs before continuing. |
Is the DTC Active at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| 1. | Turn the ignition off. |
| NOTE: | The PCM tests the ETC Motor by opening and closing the Throttle Plate before starting the engine. If during this test the Throttle plate does not open this DTC sets. |
| 2. | Remove the Air Cleaner Assembly from the Throttle Body. (Refer to 09 - Engine/Air Intake System/AIR CLEANER - Removal) |
| 3. | Check for any signs of a foreign material causing the Throttle to remain open. |
| 4. | Using a scan tool, under System Tests, perform the ETC Throttle Follower Test. |
| 5. | Have an assistant watch the throttle plate to verify it moves during the test. |
Does the Throttle Plate move?
Yes
- Go To 3
No
- Remove the debris if possible or replace the Throttle Body Assembly. (Refer to 14 - Fuel System/Fuel Injection/THROTTLE BODY - Removal) . Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
3. (K126) ETC NEGATIVE CIRCUIT SHORTED TO VOLTAGE
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| 1. | Turn the ignition off. |
| 2. | Disconnect the Throttle Body harness connector. |
| 3. | Disconnect the PCM C2 harness connector. |
| 4. | Ignition on, engine not running. |
| 5. | Measure the voltage on the (K126) ETC Negative circuit at the Throttle Body harness connector. |
Is there any voltage present?
Yes
- Repair the short to voltage on the (K126) ETC Negative circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
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Go To 4
4. (K124) ETC POSITIVE CIRCUIT OPEN
| 1. | Turn the ignition off. |
Do not probe the PCM harness connectors. Probing the PCM harness
connectors will damage the PCM terminals resulting in poor terminal
to pin connection. Install the GPEC Diagnostic Adaptor to perform
the diagnosis.
CAUTION:
| 2. | Connect the Adapter, GPEC Diagnostic 10436 . |
| 3. | Measure the resistance of the (K124) ETC Positive circuit from the Throttle Body harness connector to the GPEC Adaptor. |
Is the resistance below 5.0 Ohms?
Yes
- Go To 5
No
- Repair the open in the (K124) ETC Positive circuit.
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Perform the POWERTRAIN
VERIFICATION TEST. (Refer to
28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard
Procedure).
5. (K126) ETC NEGATIVE CIRCUIT OPEN
| 1. | Measure the resistance of the (K126) ETC Negative circuit from the Throttle Body harness connector to the GPEC Adaptor. |
Is the resistance below 5.0 Ohms?
Yes
- Go To 6
No
- Repair the open in the (K126) ETC Negative circuit.
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Perform the POWERTRAIN
VERIFICATION TEST. (Refer to
28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard
Procedure).
6. (K124) ETC POSITIVE CIRCUIT SHORTED TO GROUND
 |
| 1. | Measure the resistance between a known good ground and the (K124) ETC Positive circuit at the Throttle Body harness connector. |
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (K124) ETC Positive circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
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Go To 7
7. (K126) ETC NEGATIVE CIRCUIT SHORTED TO GROUND
 |
| 1. | Measure the resistance between a known good ground and the (K126) ETC Negative circuit at the Throttle Body harness connector. |
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (K126) ETC Negative circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
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Go To 8
8. POWERTRAIN CONTROL MODULE (PCM)
| 1. | Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM). |
| 2. | Look for any chafed, pierced, pinched or partially broken wires. |
| 3. | Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. |
| 4. | Perform any Technical Service Bulletins that may apply. |
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Replace and program the Powertrain Control Module in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control - Removal) .
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).