P1682
DTC P1682
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 voltage circuits supplied to the engine control module (ECM). The first ignition circuit is provided by the engine controls ignition relay or powertrain relay, through a fuse. This ignition voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation. The second ignition voltage circuit is supplied by the run/crank relay through a fuse, and is used to power the remaining internal ECM circuits. If the ECM detects a voltage difference between the 2 ignition voltage circuits, DTC P1682 will set.
Conditions for Running the DTC
* The ignition is ON.
* System voltage is more than 6 V.
* 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 V between the 2 ignition voltage circuits for less than 1 s.
Action Taken When the DTC Sets
DTC P1682 is a Type A DTC.
Conditions for Clearing the DTC
DTC P1682 is a Type A DTC.
Reference Information
Schematic Reference
* Engine Controls Schematics ([1][2]Electrical Diagrams)
* Power Distribution Schematics (Power Distribution Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Electrical Center Identification Views (Application and ID)
* Probing Electrical Connectors (Probing Electrical Connectors)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Note: On the scan tool, the powertrain relay is referred to as the EC ignition relay.
1. If DTC P0685 or P0690 is set, diagnose that DTC first.
2. Ignition ON, observe the scan tool Ignition 1 Voltage signal and the EC Ignition Relay Feedback signal parameters. There should be no more than 3 V difference between the two parameters.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Ignition ON, observe the Ignition 1 Signal and the EC Ignition Relay Feedback scan tool parameter to determine which is more than 3 V lower than the other.
Note: The Ignition 1 Signal is supplied by the Run/Crank relay. The EC Ignition Relay Feedback signal is supplied by the powertrain relay.
2. Ignition OFF, remove the relay that corresponds to the scan tool parameter that is more than 3 V lower.
Note: A resistance of 6 ohm or greater in the circuit/underhood fuse block will cause the DTC to set.
3. Connect a 20 A fused jumper wire between B+ and the applicable ignition voltage circuit terminal 30. Ignition ON, verify that the applicable scan tool parameter displays between 9-14 V.
• If the applicable scan tool parameter is less than the specified value, test the ignition voltage circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
4. Ignition OFF, connect a DMM set to the diode setting between the control circuit terminal 85 and ground. Verify the DMM displays OL.
• If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
5. Ignition ON, verify the DMM displays less than 1 V.
• If not the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
6. If all circuits test normal, replace the applicable relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming