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DTC P068A or P068B

DTC P068A or P068B

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 P068A 00

Engine Controls Ignition Relay De-Energized Too Early

DTC P068B 00

Engine Controls Ignition Relay De-Energized Too Late

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Relay Coil Ignition

P068A 00

P068A 00

-

-

Relay Switch Ignition

P068A 00

P068A 00

-

-

Relay Coil Control

P068B 00

-

-

-

Relay Output Control

-

-

P068B 00

-



Circuit/System Description

The powertrain relay, is controlled by the engine control module (ECM) depending upon input from the ignition switch. Battery positive voltage is supplied to the relay coil and switch. When the ignition switch is turned to the ON position, the ECM will provide ground on the control circuit of the relay using a low side driver. This will allow voltage through the relay switch contacts to the components. The ECM monitors the voltage level on the control circuit of the relay.

Conditions for Running the DTC


P068A

• The ignition is ON or the engine is running.

• The DTCs runs continuously when the above condition are met.



P068B

• The ignition is OFF.

• The DTC runs continuously until the ECM powers down.


Conditions for Setting the DTC

The ECM detects the powertrain relay control circuit is open, shorted to ground, or shorted to voltage.

Action Taken When the DTC Sets

DTCs P068A or P068B are Type C DTCs.

Conditions for Clearing the DTC

DTCs P068A or P068B are Type C DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• 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

If you were sent here from engine cranks but does not run proceed to Circuit/System Testing.



1. Ignition ON, check the diagnostic trouble code (DTC) information with a scan tool. DTC P068A or P068B are not set.

2. Cycle the ignition from OFF to ON. You should hear and feel an audible click from the KR75 Powertrain Relay. Repeat as necessary in order to verify KR75 Powertrain Relay operation.

3. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. 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 KR75 Powertrain Relay.

2. Ignition ON, verify that a test lamp illuminates between the relay coil ignition voltage circuit terminal 2 and ground.

3. If the test lamp does not illuminate, repair the relay coil ignition voltage circuit for a short to ground or an open/high resistance.

4. Ignition OFF, connect a test lamp between the relay coil control circuit terminal 1 and the relay coil ignition voltage circuit terminal 2. The test lamp should not be illuminated.

5. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

6. Ignition ON. The test lamp should turn ON.

7. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

8. Connect a 20 A fused jumper wire between the relay switch B+ circuit terminal 3 and the relay switch ignition voltage circuit terminal 5.

9. Attempt to start the engine. The engine should start.

10. If the engine does not start, test the ignition circuit between the KR75 Powertrain Relay and the K20 Engine Control Module for a short to ground or for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

11. If all circuits test normal, test or replace the KR75 Powertrain Relay.


Component Testing


Dynamic Test

1. Ignition OFF, disconnect the main ignition relay.

2. Test for 70-110 Ω between terminals 1 and 2.

3. If not within the specified range, replace the KR75 Powertrain Relay.

4. Test for infinite resistance between the following terminals:

• 3 and 1

• 3 and 5

• 3 and 2

• 2 and 5

5. If not the specified value, replace the KR75 Powertrain Relay.

6. Install a 10 A fused jumper wire between relay terminal 2 and 12 V. Install a jumper wire between relay terminal 1 and ground. Test for less than 2 Ω between terminals 3 and 5.

7. If greater than the specified range, replace the KR75 Powertrain Relay.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Ignition Relay Diagnosis

• Control Module References for ECM replacement, setup, and programming