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 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.
* 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.
The engine may operate in a reduced engine power mode.
Conditions for Clearing the DTC
DTC P1682 is a Type A DTC.
Circuit/System Verification
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
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 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
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 inline fuse from the ignition main 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) Relay Replacement (Within an Electrical Center)
* Underhood Electrical Center or Junction Block Replacement.