2010 Cadillac CTS Sedan AWD V6-3.0L Page 1593
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
Diagnostic Fault Information
Circuit/System Description
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 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.
Conditions for Running the DTC
P0685, P0686, and P0687
* The ignition voltage is between 10-18 V.
* The engine speed is greater than 80 RPM.
* The powertrain relay has been commanded ON and OFF.
* The DTCs run continuously once the above condition is met.
P0689 and P0690
* The ignition voltage is between 10-18 V.
* The ignition is ON.
* The DTCs runs continuously once the above condition is met.
Conditions for Setting the DTC
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.
Action Taken When the DTC Sets
DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
Diagnostic Aids
* This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test (See:
Starting and Charging/Testing and Inspection/Component Tests and General Diagnostics/Battery Inspection/Test).
* 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
