Circuit Description
The throttle actuator control (TAC) system uses 2 accelerator pedal position (APP) sensors to monitor the pedal position. Two processors are also used to monitor the TAC system data. The engine control module (ECM) performs an intrusive test in order to detect that the APP signals are not shorted together. The ECM accomplishes this by pulling the APP sensor 2 low momentarily and looking for sensor 1 to also be low. The TAC system also performs this test on the throttle position (TP) sensors. This diagnostic monitors the transistor used to pull one pedal and one throttle sensor to ground simultaneously. Additionally, both processors monitor each other's data to verify that the indicated APP calculation is correct.
If the transistor does not toggle within a calibrated period, or the indicated APP calculation is incorrect , DTC P1680 sets
DTC Description
This diagnostic procedure supports the following DTC:
DTC P1680 Control Module Accelerator Pedal Position (APP) System Performance
Conditions for Running the DTC
| • | The system voltage is more than 5.23 volts. |
| • | The ignition is in Unlock/Accessory or Run position. |
| • | DTCs P0601, P0602, P0604, P0606, P0607 or P1621 are not set. |
Conditions for Setting the DTC
| • | The APP sensor 2 voltage is more than 1.75 volts for more than 0.3 second during the intrusive test. |
| • | The APP sensor calculations in the main processor differ from the motor control processor by more than 0.142 volt. |
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. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Is DTC P0602 set? | -- | Go to Step 3 | Go to Step 5 | |
3 | Program the engine control module (ECM). Refer to Service Programming System (SPS) . Does DTC P0602 reset? | -- | Go to Step 4 | Go to Step 8 |
4 |
Does DTC P0602 reset? | -- | Go to Step 7 | Go to Step 8 |
Is the resistance less than the specified value? | 450 ohms | Go to Step 6 | Go to Step 7 | |
6 | Replace the accelerator pedal assembly. Refer to Accelerator Pedal Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
7 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 8 | -- |
8 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 9 |
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |
