DTC P1682. GMC Truck Canyon Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2007 🢒 Canyon Pickup - 2WD 🢒 DTC 🢒 DTC P1682

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	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

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition 1 Voltage (Powertrain Relay)	P1682, P2176	P1516, P1682, P2101	--	--
Ignition 1 Voltage (Ignition Main Relay)	--	P1682	P0575, P0650	--

Typical Scan Tool Data

EC Ignition Relay Feedback

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON Engine OFF. Powertrain Relay commanded ON
Ignition 1 Voltage	0 Volts	0 Volts	12 Volts

Ignition 1 Signal

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON Engine OFF. Ignition Main Relay commanded ON
Ignition 1 Voltage	0 Volts	0 Volts	12 Volts

There are 2 ignition 1 voltage circuits supplied to the powertrain control module (PCM). 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 PCM circuits associated with the throttle actuator control (TAC) operation. The ignition main relay provides the second ignition 1 voltage circuit to the PCM through a fuse. This ignition 1 voltage provides power to other internal PCM circuits, except those associated with TAC operation. The PCM continuously monitors the voltage level difference between the 2 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.

•	Engine may operate in a reduced engine power mode.

Conditions for Clearing the DTC

DTC P1682 is a Type A DTC.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

•	Scan Tool Data List

•	Scan Tool Output Controls

Circuit/System Verification

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 3 volts difference between the 2 parameters.
Ignition OFF, observe the ignition 1 voltage signal parameter on the scan tool. The parameter value should be 0 volts before the PCM powers down.

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.

Ignition ON, verify that B+ is available to both test points of the fuse from the powertrain relay to the PCM.

⇒	If B+ is only available on one test point of the fuse, test the ignition 1 voltage circuit from the fuse to the PCM for a short to ground. If the circuit tests normal, replace the PCM.

⇒	If B+ is not available on either test point of the fuse, replace the underhood fuse block.

Ignition OFF, disconnect the PCM C1 connector.
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 conditions. If the circuit tests normal, replace the PCM.

If all circuits test normal, replace the PCM.

Testing the EC Ignition Relay Feedback Circuit