P1518

CIRCUIT DESCRIPTION
The Throttle Actuator Control (TAC) module and the Powertrain Control Module (PCM) communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity but also adequate system voltage. This diagnostic monitors the accuracy of the serial data transmitted between the TAC module and the PCM. If the PCM of the TAC module detects a loss of data or invalid data, this DTC sets.

CONDITIONS FOR RUNNING THE DTC
The ignition switch is in the crank or run position.

CONDITIONS FOR SETTING THE DTC
Invalid or missing serial data messages are detected for a predetermined period of time.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC "Last Test Failed" clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm~up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS
Inspect for the following:

IMPORTANT: DTC P1518 sets if the battery voltage is low or the PCM is replaced or reflashed. If the customer's concern is slow cranking, or if the engine is not cranking because the battery voltage is low, ignore DTC P1518. Clear any DTCs from memory that may have set from the low battery voltage condition. If the condition is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-5:

Steps 6-19:

The number below refers to the step number on the diagnostic table.
19. When the PCM detects a condition within the Electronic Throttle Control (ETC) system other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Keep this in mind when reviewing captured DTC info.