P1518
DTC P1518CIRCUIT DESCRIPTION
The throttle actuator control (TAC) module and the powertrain control module (PCM) communicate using 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 detects a loss of data or invalid data, or if the throttle limit is exceeded while operating in the Reduced Engine Power mode, DTC P1518 sets.
CONDITIONS FOR RUNNING THE DTC
- The ignition is in the crank or run position.
- The ignition voltage is more than 5.23 volts.
- The communication between the TAC module and the PCM must be valid.
CONDITIONS FOR SETTING THE DTC
- Invalid or missing serial data messages are detected for a predetermined period of time
OR
- The throttle limit is exceeded while operating in the Reduced Engine Power mode
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 and/or the Failure Records.
- The control module commands the TAC system to operate in the Reduced Engine Power mode.
OR
- Under certain conditions the control module commands the engine OFF.
- The message center displays Reduced Engine Power.
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.
- Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS
- 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 Diagnostic Strategies
TEST
