P1682
DTC P1682
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)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 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.
* The system voltage is more than 5.23 volts.
* The 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 ignition main 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.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Engine Control Module Description (Engine Control Module Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
1. If DTCs P0685 or P0690 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 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
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 conditions. 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 (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning)for ECM replacement, setup, and programming