Circuit Description
The Throttle Actuator Control (TAC) System determines the drivers intent and then calculates the appropriate throttle response. The TAC system achieves throttle positioning by providing a pulse width modulated voltage to the TAC motor. The powertrain control module (PCM) is the control center for the TAC system. Ignition 1 voltage is supplied on two separate circuits to the PCM. If the PCM detects a voltage difference between the two circuits, DTC P1682 sets.
DTC Descriptor
This diagnostic supports the following DTC:
DTC P1682 Ignition 1 Switch Circuit 2
Conditions for Running the DTC
| • | The ignition is in unlock, accessory, run, or crank mode. |
| • | DTC P1682 runs continuously when the above condition is met. |
Conditions for Setting the DTC
The ignition 1 voltage is less than 10 volts for more than 10 seconds.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if there is voltage present to the ECM fuse.
-
This step determines if voltage is present at the PCM.
-
This step determines if the PCM ignition 1 voltage circuit is shorted to ground.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions |
With a test lamp connected to ground, probe both sides of the 15-amp ECM fuse. Does the test lamp illuminate on both sides of the fuse? | -- | Go to Step 5 | Go to Step 4 | |
4 | Does the test lamp illuminate on one side of the fuse? | -- | Go to Step 6 | |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | |
7 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
8 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 10 |
10 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
