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For 1990-2009 cars only

DTC Descriptor

DTC P1682: Ignition 1 Switch Circuit 2

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Switch Circuit 2

P1682

P1682

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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 ETC/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 ignition main 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 all 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

    • 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/Failure Records.

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

    • This test procedure requires that the vehicle battery has passed a load test and is completely charged.
    • When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion , and the mating electrical terminals for tightness.
    • Use the J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views
    •  Electrical Center Identification Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Special Tools Required

J 35616 Connector Test Adapter Kit

Circuit/System Verification

With the key ON, engine OFF, monitor the ignition 1 signal parameter with a scan tool. The ignition 1 signal parameter should display battery voltage.

Circuit/System Testing

    • If DTCs P0685, P0689, or P0690 are set, test and repair those DTCs first.
    • With the ignition ON, and the engine OFF, test for ignition 1 voltage at both test points of the ECM IGN fuse in the underhood fuse block.

       Important: The ignition main relay that is shown on the electrical wiring schematic is not serviceable. It is soldered to the bus bar, internal to the underhood fuse block. If it is determined that the ignition main relay is not functioning correctly, the underhood fuse block must be replaced.

       ⇒If the ignition  1 voltage is not present on either test point of the ECM IGN fuse, then replace underhood fuse block.
       ⇒If the ignition 1 voltage is present on one test point of the ECM IGN fuse, then repair the short to ground in the ignition 1 voltage circuit to the electronic control module (ECM). If the wire circuit tests normal, then 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 electrical connector, and the ECM electrical connectors, which contains the ignition 1 voltage circuit. If the electrical connectors test normal, then repair the ignition 1 voltage circuit, for an open or high resistance. All wire circuit resistance should measure 2 ohms or less. If the wire circuit tests normal, then replace the ECM.

Repair Instructions

    •  Control Module References for ECM replacement, setup, and programming.
    •  Underhood Electrical Center or Junction Block Replacement

Repair Verification

  1. Install any components or connectors that have been removed or replaced during diagnosis.
  2. Perform any adjustments, programming, or setup procedures that are required when a component or module is removed or replaced.
  3. Clear the DTCs.
  4. Turn OFF the ignition for 60 seconds. If the repair was related to a DTC, duplicate the condition for running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure. Or if the repair was symptom related, duplicate the condition under which the customer concern occurred to verify the repair. If the customer concerns re-occurs, return to Symptoms - Engine Controls and perform the appropriate symptom diagnostic.