Circuit Description
The throttle actuator control (TAC) module contains data which is essential for proper TAC system operation. The TAC module continuously tests the integrity of this data. When the TAC module is unable to write or read data to and from randam access memory (RAM) or the TAC module is unable to correctly read data from the flash memory or an internal TAC module processor fault is detected, this diagnostic trouble code (DTC) sets.
Conditions for Running the DTC
| • | DTC P1518 is not set. |
| • | The ignition switch is in the crank or run position. |
| • | The ignition voltage is more than 6 volts. |
Conditions for Setting the DTC
| • | The TAC module determines that an internal data test did not pass. |
| • | All of the above conditions are met for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) when this diagnostic runs and fails. |
| • | The Reduced Engine Power message is displayed on the drivers information center. |
| • | The PCM records the operating conditions at the time during which the diagnostic fails. The PCM stores this information in the Freeze Frame and Failure Records. |
| • | If no other TAC system DTCs are set, the TAC system will operate in Reduced Engine Power mode. If certain TAC system DTCs are set at the same time, the TAC system either defaults to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or if the TAC commands the engine to shut down. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive drive trips during which the diagnostic runs and does not fail. |
| • | A last test failed Current DTC will clear when the diagnostic runs and does not fail. |
| • | A History DTC clears after forty consecutive warm-up cycles if this or any other emission related diagnostic does not report any failures. |
| • | Clear the MIL/DTC information with a scan tool. |
Diagnostic Aids
Important:
• Remove any debris from the PCM or TAC module connector surfaces
before servicing the PCM or TAC module. Inspect the PCM or TAC module connector
gaskets when diagnosing or replacing the modules. Ensure that the
gaskets are installed correctly. The gaskets prevent contaminate intrusion
into the PCM or TAC modules. • For any test that requires probing the PCM or a component
harness connector, use the J 35616
connector test adapter kit . Using this kit prevents
damage to the harness or component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | Ensure the starting and charging systems are operating properly. Low system voltage causes this DTC to set. |
| • | When the TAC module detects a problem within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Is the action complete? | -- | -- | |
3 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
