Diagnostic Instructions
DTC Descriptor
DTC P1682: Ignition Switch Circuit Malfunction
Diagnostic Fault Information
Circuit
| Short to Ground
| Open/High Resistance
| Short to Voltage
| Signal Performance
|
Ignition 1 Switch Circuit 2
| P1682
| P1682
| --
| --
|
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 the ECM fuse, located in the underhood fuse block. This
ignition 1 voltage circuit supplies power to all the internal ECM circuits
associated with the throttle actuator control (TAC) operation, and to both TAC motor
control circuits to the throttle body. The run/crank relay provides the second ignition 1
voltage circuit to the ECM, through the ECM-IGN fuse located in the underhood fuse
block. This ignition 1 voltage provides power to other internal ECM circuits,
except those associated with TAC operation. The ECM continuously monitors both ignition 1
voltage circuits. If the ECM detects a voltage level difference between the two circuits,
DTC P1682 will set.
Conditions for Running the DTC
| • | The ignition switch is turned ON. |
| • | The powertrain relay has been commanded ON. |
| • | DTC P1682 runs continuously. |
Conditions for Setting the DTC
| • | The voltage level difference is more than 3 volts between the 2 ignition 1
voltage circuits to the ECM. |
| • | The condition is present for more than 3 seconds. |
Action Taken when the DTC Sets
DTC P1682 is a type A store Only DTC.
Conditions for Clearing the MIL/DTC
DTC P1682 is a type A store Only DTC.
Diagnostic Aids
| • | This test procedure requires that the vehicle battery has passed a load
test and is completely charged. |
| • | When disconnecting harness connectors or removing fuses and relays from
a fuse block, always inspect the component harness terminals for corrosion and the
mating harness terminals for tightness. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Scan Tool Reference
Control Module References
Circuit/System Verification
Ignition ON, engine OFF, monitor the ignition 1 signal parameter with
a scan tool. The ignition 1 signal parameter should display battery voltage.
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.
Repair Instructions
Perform the
Diagnostic Repair Verification
after
completing the diagnostic procedure.
Circuit/System Testing
| • | If DTCs P0685, P0689 or P0690 are set, test and repair those DTCs
first. |
| • | Ignition ON, engine OFF, test for ignition 1 voltage at both test
points of the ECM-IGN fuse in the underhood fuse block. |
| ⇒ | If the ignition 1 voltage is present on one test point of the ECM-IGN
fuse, then repair the short to ground or an open/high resistance in the ignition 1
voltage circuit to the ECM. If the wire circuit tests normal, replace the ECM. |
| ⇒ | If the ignition 1 voltage is present on both test points of the ECM-IGN
fuse then inspect and test for loose and corroded terminals at the underhood fuse
block harness connector and the ECM harness connectors, which contains the ignition 1
voltage circuit. If the harness connectors test normal, then test the ignition 1
voltage circuit, for an open/high resistance. All wire circuit resistance should measure 2
ohms or less. If the wire circuit tests normal, refer to
Ignition Relay Diagnosis
. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after
completing the diagnostic procedure.
