P1682

DTC P1682 (LUW)

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 powertrain relay, through fuse F10UA 15 A. 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 fuse F5UA 15 A, 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 5.5 v.
* Powertrain relay is commanded ON.
* DTC P1682 runs continuously when the above conditions are met.

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 (LUW) [1][2]Electrical Diagrams
Connector End View Reference

Component Connector End Views Sunshade - Left (D6I)
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* 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 Control Module References for scan tool information

Circuit/System Verification

Note: On the scan tool, the powertrain relay is referred to as the Engine Controls Ignition Relay.

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTCs P0685, P0689, or P0690 are not set.

• If any of the above DTCs are set, refer to DTC P0685, P0689, or P0690 (LUW) P0685.

2. Ignition ON, observe the scan tool Engine Control Ignition Relay Feedback signal parameter. The parameter should display B+.

• If less than the specified value, refer to DTC P0685, P0689, or P0690 (LUW) P0685.

3. Ignition ON, observe the scan tool Ignition 1 Signal and the Engine Control Ignition Relay Feedback signal parameters. Both parameters should display within 3 V.
4. 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

1. Ignition OFF, disconnect the K20 Engine Control Module connector X1.
2. Ignition ON, test for B+ between the K20 Engine Control Module harness connector terminals listed below and ground.

* Terminal X1 3
* Terminal X1 14

• If less than the specified value, repair the appropriate ignition voltage circuits for a short to ground or an open/high resistance.

3. If all circuits test normal, replace the K20 Engine Control Module.

Repair Instructions

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

Control Module References Control Module References for engine control module replacement, programming and setup