2010 Cadillac CTS Sedan AWD V6-3.0L Page 1599
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0685
- Engine Controls Ignition Relay Control Circuit
DTC P0690
- Engine Controls Ignition Relay Feedback Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The engine controls 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 under-hood fuse block.
The ignition 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 voltage circuit to confirm that the powertrain relay contacts have closed.
Conditions for Running the DTC
* The ignition is ON.
* The ignition voltage is between 11-18 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.
P0690
* The ECM detects the engine controls ignition relay feedback circuit is greater than 2 V when the relay is commanded OFF.
* The ECM detects the engine controls ignition relay feedback circuit is greater than 18 V when the relay is commanded ON.
* The condition is present for greater than 2 s.
Action Taken When the DTC Sets
DTCs P0685 and P0690 are Type B DTCs.
Conditions for Clearing the DTC
