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 2 separate circuits to the PCM. If the PCM detects a voltage difference between the 2 circuits, DTC P1682 sets.
This diagnostic procedure supports the following DTC:
DTC P1682 Ignition 1 Switch Circuit 2
• | The ignition is in Unlock, Accessory, Run, or Crank mode. |
• | DTC P1682 runs continuously when the above condition is met. |
The ignition 1 voltage is less than 10 volts for more than 10 seconds.
• | 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. |
• | 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. |
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 - Vehicle? | -- | Go to Step 2 | |
2 |
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
With a test lamp connected to ground, probe both sides of the 15-amp ECM/ETC 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. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
8 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. 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 |