Buick Regal: DTC P0685-P0687, P0689, P0690, or 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 Descriptors

DTC P0685

Engine Controls Ignition Relay Control Circuit

DTC P0686

Engine Controls Ignition Relay Control Circuit Low Voltage

DTC P0687

Engine Controls Ignition Relay Control Circuit High Voltage

DTC P0689

Engine Controls Ignition Relay Feedback Circuit Low Voltage

DTC P0690

Engine Controls Ignition Relay Feedback Circuit High Voltage

DTC P1682

Ignition 1 Switch Circuit 2

Diagnostic Fault Information

Engine Controls Ignition Relay

Typical Scan Tool Data

Engine Controls Ignition Relay Control Circuit Low Voltage, Open, and High Voltage Test Status - Component Commanded OFF

Engine Controls Ignition Relay Control Circuit Low Voltage, Open, and High Voltage Test Status - Component Commanded ON

Circuit/System Description

There are 2 ignition voltage circuits supplied to the engine control module (ECM). One is supplied by the engine controls ignition relay, and the other is supplied by the ignition main relay. The ECM monitors and compares the ignition voltage supplied by the 2 relays.

Conditions for Running the DTC

P0685, P0686, P0687

The DTC runs when Ignition 1 signal voltage is greater than 11 V.

P0689

• DTC P0685 is not set.
• The engine controls ignition relay is commanded ON.
• Ignition 1 signal voltage is greater than 11 V.
• The DTC runs continuously when the above conditions are met.

P0690

• DTC P0685 is not set.
• The engine controls ignition relay is commanded OFF.
• The DTC runs continuously when the above conditions are met.

P1682

• The engine controls ignition relay is commanded ON.
• Ignition voltage is greater than 5.5 V.
• The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P0685

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 2 s.

P0686

The ECM detects a short to ground on the control circuit for greater than 2 s.

P0687

The ECM detects a short to voltage on the control circuit for greater than 2 s.

P0689

The ECM detects the engine controls ignition relay feedback circuit is less than 5 V.

P0690

The ECM detects the engine controls ignition relay feedback circuit is greater than 4 V for greater than 5 s.

P1682

The ECM detects that the voltage level difference is greater than 3 V between the 2 ignition voltage circuits for greater than 1 s.

Action Taken When the DTC Sets

North America

• DTCs P0685, P0686, P0687, and P0690 are Type B DTCs.
• DTC P0689 is a Type C DTC.
• DTC P1682 is a Type A DTC.

Europe

• DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
• DTC P1682 is a Type A DTC.

Conditions for Clearing the DTC

North America

• DTCs P0685, P0686, P0687, and P0690 are Type B DTCs.
• DTC P0689 is a Type C DTC.
• DTC P1682 is a Type A DTC.

Europe

• DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
• DTC P1682 is a Type A DTC.

Diagnostic Aids

The engine controls ignition relay may also be labeled the powertrain relay, the engine control module relay, or the main relay. The ignition main relay may also be labeled the run/crank relay, the ignition run relay, the ignition 1 relay, or the ignition relay.

Reference Information

Schematic Reference

• Engine Controls Wiring Schematics (LTG)
• Power Distribution Wiring Schematics

Connector End View Reference

Component Connector End View Index

Component View Reference

Powertrain Component Views

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Electrical Center Identification Views
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: A short to voltage on other components may cause DTC P0690 to set. If any other DTC is set, diagnose that DTC first.

If you were sent here from Engine Cranks But Does Not Run, proceed to Circuit/System Testing.

1. Ignition ON, observe the scan tool DTC information. Verify DTC P0685, P0686, P0687, P0689, P0690, or P1682 is not set.

• If any of the DTCs are set

Refer to Circuit/System Testing.

• Go to next step: If none of the DTCs are set

2. 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.

• If any of the DTCs are set

Refer to Circuit/System Testing.

• Go to next step: If none of the DTCs are set

3. All OK.

Circuit/System Testing

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing unless sent here from Engine Cranks But Does Not Run.

1. Ignition OFF, disconnect the KR75 Engine Controls Ignition Relay.

2. Verify a test lamp illuminates between ground and the relay circuit terminals listed below:

• Terminal 85
• Terminal 30
• If the test lamp does not illuminate

Replace the front compartment fuse block.

• Go to next step: If the test lamp illuminates

NOTE:

• Go to next step: High resistance in the circuit/underhood fuse block for either the KR75 Engine Controls Ignition Relay or the KR73 Ignition Main Relay can cause DTC P1682 to set.
• Go to next step: A short to voltage on any of the circuits supplied by the engine controls ignition relay can cause DTC P0690 to set.

3. Ignition ON.

4. Verify that a test lamp does not illuminate between the ignition voltage circuit terminal 87 and ground.

• If the test lamp illuminates

1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
2. Ignition ON.
3. Test for less than 1 V between ground and connector terminals 73.
   • If 1 V or greater, repair the short to voltage in the circuit.
   • If less than 1 V, replace the K20 Engine Control Module.

• Go to next step: If the test lamp does not illuminate

5. Ignition OFF, connect a 20 A fused jumper wire between the relay switch B+ circuit terminal 30 and the relay switch ignition voltage circuit terminal 87.

6. Ignition ON.

7. Verify the scan tool Engine Controls Ignition Relay Feedback Signal parameter displays B+.

• If B+ is not displayed

1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module
2. Test for less than 2 Ω in the relay switch ignition voltage circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • Go to next step: If less than 2 Ω
3. Test for infinite resistance between the relay switch ignition voltage circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, replace the K20 Engine Control Module.

• Go to next step: If B+ is displayed

8. Ignition OFF, connect a DMM, set to the diode setting, between control circuit terminal 86 and ground.

9. Verify the DMM displays OL.

• If OL is not displayed

1. Disconnect the X1 harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between ground and the relay control circuit.
   • If less than infinite resistance, repair the short to ground in the circuit.
   • If infinite resistance, replace the K20 Engine Control Module.

• Go to next step: If OL is displayed

10. Ignition ON.

11. Verify the DMM displays less than 1 V.

• If 1 V or greater

1. Ignition OFF, disconnect the X1 connector at the K20 Engine Control Module.
2. Ignition ON.
3. Test for less than 1 V on the relay control circuit.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V
4. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • if less than 2 Ω, replace the K20 Engine Control Module.

• Go to next step: If less than 1 V

12. Test or replace the KR75 Engine Controls Ignition Relay.

Component Testing

Relay Test

1. Ignition OFF, disconnect the KR75 Engine Controls Ignition Relay.

2. Test for 70 - 110 Ω between terminals 85 and 86:

• If less than 70 Ω or greater than 110 Ω

Replace the KR75 Engine Controls Ignition Relay.

• Go to next step: If between 70 - 110 Ω

3. Test for infinite resistance between the terminals listed below:

• 30 and 86
• 30 and 87
• 30 and 85
• 85 and 87
• If less than infinite resistance

Replace the KR75 Engine Controls Ignition Relay.

• Go to next step: If infinite resistance

4. Install a 20 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.

5. Test for less than 2 Ω between terminals 30 and 87.

• If 2 Ω or greater

Replace the KR75 Engine Controls Ignition Relay.

• Go to next step: If less than 2 Ω

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Engine Wiring Harness Junction Block Replacement (LTG) or Engine Wiring Harness Junction Block Replacement (LGX) for front compartment fuse block replacement.
• Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an Electrical Center)
• Control Module References for engine control module replacement, programming, and setup.

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