P1682

DTC P1682

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 1 Switch Circuit 2

Diagnostic Fault Information






Typical Scan Tool Data










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 a fuse. This ignition 1 voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation. The run/crank relay provides the second ignition 1 voltage circuit to the ECM, through a fuse. This ignition 1 voltage provides power to other internal ECM circuits, except those associated with TAC operation. The ECM continuously monitors the voltage level difference between the two circuits.

Conditions for Running the DTC

* The ignition is in the Unlock/Accessory, Run, or Crank position.
* System voltage is more than 5.23 volts.
* Powertrain relay is commanded ON.
* DTC P1682 runs continuously when the above conditions are met.

Conditions for Setting the DTC

The ignition 1 voltage of the Run/Crank relay is more than 3 volts different than the ignition 1 voltage of the powertrain relay for more than 2 seconds.

Action Taken When the DTC Sets

* DTC P1682 is a Type B DTC.
* Engine may operate in a reduced engine power mode.

Conditions for Clearing the DTC

DTC P1682 is a Type B DTC.

Diagnostic Aids

This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test. Battery Inspection/Test

Circuit/System Verification

1. If DTCs P0685, P0689, P0690, or B1380 are set, diagnose those DTCs first.
2. Ignition ON, engine OFF, observe 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 two parameters.
3. Ignition OFF, observe the ignition 1 voltage signal parameter, on the scan tool. The parameter value should be 0 volts, before the ECM powers down.

Circuit/System Testing

1. Ignition ON, observe the Ignition 1 Signal and EC Ignition Relay Feedback scan tool parameters to determine which is less than B+.
2. Ignition OFF, remove the relay that corresponds to the scan tool parameter that is less than B+.

Important: 6 ohms or greater in the circuit/underhood fuseblock will cause the DTC to set.

3. Ignition On, connect a 3A fused jumper wire between B+ and the applicable ignition 1 circuit terminal. Verify that the applicable scan tool parameter displays B+.

• If the applicable scan tool parameter is less than the specified value, test the ignition 1 circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

4. If all circuits test normal, test or replace the applicable relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Control Module References for ECM replacement, setup, and programming Programming and Relearning
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)