Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category |
DTC Descriptor
DTC P1682: Ignition Switch Circuit MalfunctionDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Switch Circuit 2 | P1682 | P1682 | -- | -- |
Circuit/System Description
There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition 1 voltage circuit is provided by the powertrain relay, through the ECM fuse, located in the underhood fuse block. This ignition 1 voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation, and to both TAC motor control circuits to the throttle body. The run/crank relay provides the second ignition 1 voltage circuit to the ECM, through the ECM-IGN fuse located in the underhood fuse block. This ignition 1 voltage provides power to other internal ECM circuits, except those associated with TAC operation. The ECM continuously monitors both ignition 1 voltage circuits. If the ECM detects a voltage level difference between the two circuits, DTC P1682 will set.
Conditions for Running the DTC
| • | The ignition switch is turned ON. |
| • | The powertrain relay has been commanded ON. |
| • | DTC P1682 runs continuously. |
Conditions for Setting the DTC
| • | The voltage level difference is more than 3 volts between the 2 ignition 1 voltage circuits to the ECM. |
| • | The condition is present for more than 3 seconds. |
Action Taken when the DTC Sets
DTC P1682 is a type A store Only DTC.
Conditions for Clearing the MIL/DTC
DTC P1682 is a type A store Only DTC.
Diagnostic Aids
| • | This test procedure requires that the vehicle battery has passed a load test and is completely charged. |
| • | When disconnecting harness connectors or removing fuses and relays from a fuse block, always inspect the component harness terminals for corrosion and the mating harness terminals for tightness. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, engine OFF, monitor the ignition 1 signal parameter with a scan tool. The ignition 1 signal parameter should display battery voltage.
If the vehicle passes the Circuit/System Verification test operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records data list.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Circuit/System Testing
| • | If DTCs P0685, P0689 or P0690 are set, test and repair those DTCs first. |
| • | Ignition ON, engine OFF, test for ignition 1 voltage at both test points of the ECM-IGN fuse in the underhood fuse block. |
| ⇒ | If the ignition 1 voltage is not present on either test point of the ECM-IGN fuse then refer to Starter Solenoid Does Not Click . |
| ⇒ | If the ignition 1 voltage is present on one test point of the ECM-IGN fuse, then repair the short to ground or an open/high resistance in the ignition 1 voltage circuit to the ECM. If the wire circuit tests normal, replace the ECM. |
| ⇒ | If the ignition 1 voltage is present on both test points of the ECM-IGN fuse then inspect and test for loose and corroded terminals at the underhood fuse block harness connector and the ECM harness connectors, which contains the ignition 1 voltage circuit. If the harness connectors test normal, then test the ignition 1 voltage circuit, for an open/high resistance. All wire circuit resistance should measure 2 ohms or less. If the wire circuit tests normal, refer to Ignition Relay Diagnosis . |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
