DTC P0685, P0686, P0687, P0689, or P0690 (LAU)
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DTC P0685, P0686, P0687, P0689, or P0690 (LAU)
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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
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Diagnostic Fault Information
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Circuit
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Short to Ground
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High Resistance
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Open
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Short to Voltage
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Signal Performance
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B+ Supply Voltage - Coil
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P0685
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P0685
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P0685
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-
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-
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B+ Supply Voltage - Switch
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-
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P0689
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P0689
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P0690
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-
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Relay Control Circuit
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P0686
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P0685
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P0685
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P0687
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P0685
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Ignition Voltage Circuit
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-
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P0689
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P0689
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P0690
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-
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Circuit/System Description
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The engine controls (EC) ignition relay, or powertrain relay is a normally open relay. The relay switch is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the switch contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver. When the ECM commands the powertrain relay ON, ignition voltage is supplied to several fuses in the underhood fuse block.
The ignition 1 voltage that is supplied to the ECM through the ETC fuse provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation. The ECM also monitors the voltage level on the ignition 1 voltage circuit to confirm that the powertrain relay contacts have closed.
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Conditions for Running the DTC
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P0685, P0686, and P0687
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The ignition voltage is between 10-18 V.
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The engine speed is greater than 80 RPM.
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The powertrain relay has been commanded ON and OFF.
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The DTCs run continuously once the above condition is met.
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P0689 and P0690
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The ignition voltage is between 10-18 V.
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The DTCs runs continuously once the above condition is met.
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Conditions for Setting the DTC
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P0685, P0686, and P0687
The commanded state of the driver and the actual state of the control circuit do not match for greater than 4 s or for a cumulative of 30 s.
P0689 and P0690
The ECM detects that powertrain relay feedback voltage is less than 6 V for greater than 1 s, when the powertrain relay is commanded ON or OFF. The condition exists for 4 s, or for a cumulative of 30 s.
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Action Taken When the DTC Sets
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DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
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Conditions for Clearing the MIL/DTC
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DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
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This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to
Battery Inspection/Test
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An open in the relay control circuit will cause no communication with the ECM when the ignition switch is cycled OFF and then ON after the initial failure. The malfunction indicator lamp (MIL) will flash rapidly and other relays can be heard turning on and off with the ignition ON.
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When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the mating electrical terminals for tightness.
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Use the J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals.
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Schematic Reference
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
Special Tools
J 35616
Connector Test Adapter Kit
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Circuit/System Verification
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1.
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Note
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If you were sent here from Engine Cranks But Does Not Run proceed to Circuit/System Testing.
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Engine running, command the Engine Controls (EC) Ignition Relay ON and OFF with a scan tool while observing the following EC Ignition Relay control circuit status parameters:
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Engine Controls Ignition Relay Control Circuit Low Voltage Test Status
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Engine Controls Ignition Relay Control Circuit Open Test Status
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Engine Controls Ignition Relay Control Circuit High Voltage Test Status
Each parameter should display OK or Not Run.
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2.
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Ignition ON, you should be able to communicate with the ECM using a scan tool.
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3.
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Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. DTC P0685, P0686, P0687, P0689, or P0690 should not set.
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4.
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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.
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1.
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Ignition OFF, disconnect the KR75 powertrain relay.
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2.
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Ignition ON, verify a test lamp illuminates between both of the following relay battery voltage circuit terminals and ground.
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3.
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If the test lamp does not illuminate, test the relay battery voltage circuit for a short to ground or an open/high resistance.
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4.
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Note
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The ignition voltage circuit is between the powertrain relay and the ECM. The ignition voltage circuit is a feedback circuit.
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Ignition OFF, verify that a test lamp does not illuminate between the ignition voltage circuit terminal 30 and ground.
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5.
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If the test lamp illuminates, test the ignition voltage circuit for a short to voltage.
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6.
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Connect a 20 A fused jumper wire between the relay switch B+ circuit terminal 87 and the relay switch ignition voltage circuit terminal 30.
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7.
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Ignition ON, observe the scan tool EC Ignition Relay Feedback Signal parameter. The ECM should communicate, and the parameter should display 9-14 V.
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8.
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If not the specified range, or the ECM does not communicate, test the ignition voltage circuit between the powertrain relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
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9.
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Ignition OFF, verify that a test lamp does not illuminate between the control circuit terminal 85 and B+.
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10.
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If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
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11.
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Connect a DMM set to the diode setting between the control circuit terminal 85 and ground.
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12.
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Ignition ON, verify the DMM does not display OL.
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13.
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If the DMM displays OL, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
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14.
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If all circuits test normal, replace the KR75 powertrain relay.
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1.
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Note
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Depending on the application, the relay coil resistance will be within one of the following ranges.
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Test for one of the following resistance specifications between terminals 85 and 86 of the KR75 powertrain relay:
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2.
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If not within the specified range, replace the KR75 powertrain relay.
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3.
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Measure for infinite resistance between the following terminals of the KR75 powertrain relay:
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4.
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If continuity is detected, replace the KR75 powertrain relay.
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5.
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Connect a 15 A fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Measure for less than 2 Ω between terminals 30 and 87 of the relay.
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6.
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If greater than the specified value, replace the KR75 powertrain relay.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
