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 ignition main printed circuit board 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 2 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 2 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 A DTC.
* Engine may operate in a reduced engine power mode.

Conditions for Clearing the DTC

DTC P1682 is a Type A DTC.

Circuit/System Verification

1. If DTCs P0685, 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 2 volts difference, between the 2 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

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

Testing the Ignition 1 Signal Circuit

Important: A resistance of 5 ohms or greater in the circuit will cause the DTC to set.

1. Ignition ON, verify that B+ is available to both test points of the fuse from the powertrain relay to the ECM.

^ If B+ is only available on one test point of the fuse, test the ignition 1 voltage circuit from the fuse to the ECM for a short to ground. If the circuit tests normal, replace the ECM.
^ If B+ is not available on either test point of the fuse, replace the underhood fuse block.

2. Ignition OFF, disconnect the ECM C1 connector.
3. Ignition ON, verify that B+ is available at C1-19.

^ If B+ is not available, test the ignition 1 voltage circuit for an open/high resistance condition. If the circuit tests normal, replace the ECM.

4. If all circuits test normal, replace the ECM.

Testing the EC Ignition Relay Feedback Circuit

Important: A resistance of 5 ohms or greater in the circuit will cause the DTC to set.

1. Ignition OFF, remove the powertrain relay from the underhood fuse block.
2. Ignition ON, connect a 3A fused jumper wire from B+ to the powertrain ignition 1 voltage circuit terminal. Verify that the EC Ignition Relay Feedback parameter displays B+ on the scan tool.

^ If the scan tool parameter is less than the specified value, test the ignition 1 voltage circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.

Repair Instructions

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

* Relay Replacement (Attached to Wire Harness)