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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 SSR 🢒 Restraints 🢒 SIR 🢒 DTC P1682

DTC Descriptor

DTC P1682:  Ignition 1 Switch Circuit 2

Diagnostic Fault Information

Perform the prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Switch Circuit 2

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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 circuit is provided by the powertrain relay, through a fuse. This ignition 1 voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation. The second ignition 1 voltage circuit is supplied by the ignition switch through a fuse, and is used to power the remaining internal ECM circuits. If the ECM detects a voltage difference between the 2 ignition 1 voltage circuits, DTC P1682 will set.

Conditions for Running the DTC
    • The ignition is ON.
    • The powertrain relay is commanded ON.
    • DTC P1682 runs continuously.

Conditions for Setting the DTC

The ECM detects that the voltage level difference is greater than 3 volts between the 2 ignition 1 voltage circuits, for more than 3 seconds.

Action Taken When the DTC Sets

DTC P1682 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P1682 is a Type B DTC.

Diagnostic Aids
    • ยท 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 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 Information Reference

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

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

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
  1. If DTCs P0685, P0689, or P0690 are set, diagnose those DTCs first.
  2. Ignition ON, engine OFF, observe both the ignition 1 voltage signal and the EC Ignition Relay Feedback signal parameters on the scan tool. Both parameter values should display no more than 3 volts difference between the 2 parameters. 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. Another option is to refer to Testing for Intermittent Conditions and Poor Connections.

Circuit/System Testing
  1. Ignition OFF, disconnect powertrain relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the powertrain relay controlled output circuit terminal and ground.
    3. ⇒If the test lamp illuminates, test the powertrain relay controlled output circuit for a short to voltage.
  3. Ignition OFF, verify that a test lamp illuminates between the powertrain relay coil voltage supply circuit terminal and ground.
    4. ⇒If the test lamp does not illuminate, test the powertrain relay coil voltage supply circuit for a short to ground or an open/high resistance.
  4. Verify that a test lamp illuminates between the powertrain relay switch voltage supply circuit terminal and ground.
    5. ⇒If the test lamp does not illuminate, test the powertrain relay switch voltage supply circuit for an open/high resistance.
  5. Disconnect the ECM.
  6. Ignition ON, verify that a test lamp illuminates between ECM connector terminal C1-19 and ground.
    7. ⇒If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or open/high resistance.
    ⇒If the circuit tests normal and the fuse is open, replace the ECM.
  7. Ignition OFF, connect the harness connector at the ECM.
  8. Ignition ON, connect a jumper wire between the powertrain relay voltage supply circuit terminal and the powertrain relay controlled output circuit terminal. Verify the EC Ignition Relay Feedback parameter indicates battery positive voltage.
    9. ⇒If not the specified value, test the powertrain relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the ECM.
  9. Perform the component test for the powertrain relay.
    10. ⇒If the relay fails the component test, replace the relay.
    ⇒If the relay passes the component test, replace the ECM.

Component Testing
  1. Ignition OFF, disconnect the powertrain relay.
  2. Test for 70-100 ohms of resistance between terminals 85 and 86.
    3. ⇒If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If less than infinite resistance, replace the relay.
  4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 1 ohm of resistance between terminals 30 and 87.
    5. ⇒ If greater than 1 ohm, then replace the relay.

Repair Instructions

Perform the after completing the diagnostic procedure.

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