P1682
DTC P1682
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide 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 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 second ignition 1 voltage circuit is supplied by the ignition switch through a fuse, and is used to power the remaining internal ECM circuits. If the ECM detects a voltage difference between the 2 ignition 1 voltage circuits, DTC P1682 will set.
Conditions for Running the DTC
* The ignition is ON.
* System voltage is more than 5.23 volts.
* 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 volts between the 2 ignition 1 voltage circuits, for more than 3 seconds.
Action Taken When the DTC Sets
DTC P1682 is a Type B code.
Conditions for Clearing the DTC
DTC P1682 is a Type B code.
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, or P0690 are set, diagnose those DTCs first.
Important: On the scan tool, the powertrain relay is referred to as the EC ignition relay.
2. Ignition ON, engine OFF, observe both 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.
• If the vehicle passes the Circuit/System Verification test, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records data list.
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 switch 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, test the ignition 1 voltage circuit from the ignition switch for an open/high resistance or short to ground. If the circuit tests normal, replace the ignition switch.
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.
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
* Control Module References for ECM replacement, programming, and setup Programming and Relearning
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)
* Underhood Electrical Center or Junction Block Replacement