Buick Regal: DTC C0393
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 Descriptor
DTC C0393
- Rear Differential Clutch Solenoid Valve Control Circuit
- For symptom byte information, refer to Symptom Byte List
Diagnostic Fault Information
Circuit/System Description
The right and left rear differential clutch solenoid valves are
electro-hydraulic valves used to relieve pressure in the
hydraulic system. When the solenoid valves are energized, the valves are closed
and hydraulic pressure can be
accumulated. When the solenoid valves are de-energized, the valves are open and
it is not possible to build hydraulic
pressure.
Conditions for Running the DTC
- The engine is running.
- Battery voltage is between 9-16 V.
- DTC C0800 is not current.
Conditions for Setting the DTC
C0393 01
The rear differential clutch control module determines a short to battery on
the rear differential clutch solenoid valve
control circuit.
C0393 02
The rear differential clutch control module determines a short to ground on
the rear differential clutch solenoid valve
control circuit.
C0393 5A
The rear differential clutch control module determines a signal plausibility
failure.
C0393 61
The rear differential clutch control module determines the differential
clutch pump is stuck.
Action Taken When the DTC Sets
One or more of the following actions may occur:
- The electronic limited slip system is temporary inhibited for the
duration of the key cycle.
- The electronic limited slip system is disabled for the duration of the
key cycle.
- The AWD SERVICE message in the driver information center.
Conditions for Clearing the DTC
- The condition for the DTC is no longer present.
- The DTC is not detected in 40 consecutive drive cycles.
Reference Information
Schematic Reference
Rear Axle Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEW INDEX
Description and Operation
Rear Drive Axle Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
1. Verify that DTC C0393 with symptom byte 01, 02 or 5A is not set.
Refer to Circuit/System Testing.
- Go to next step: If the DTC is not set
2. Verify that DTC C0393 61 is not set.
- Perform the Rear Differential Hydraulic System Bleed Procedure with a
scan tool. Refer to Rear
Differential Hydraulic System Service Fill/Bleed
- NOTE: The Rear Differential Clutch Module can run this procedure
up to 3
attempts to get a Pass.
- Verify that DTC C0393 61 is not set.
- if DTC is set, test or replace the appropriate rear differential
clutch solenoid valve.
- Go to next step: If the DTC is not set
- All OK.
- Go to next step: If the DTC is not set
3. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the Q49 Rear
Differential Clutch Solenoid Valve, Ignition
ON/Vehicle in Service Mode.
2. Test for 5.6 - 6.4 V between the control circuit terminal 3 and ground.
- Ignition OFF, disconnect the X2 harness connector at the K47 Rear
Differential Clutch Control Module.
- Test for infinite resistance between the control circuit terminal 3 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the control circuit terminal 3 end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K47 Rear Differential Clutch Control
Module.
- Ignition OFF, disconnect the X2 harness connector at the K47 Rear
Differential Clutch Control Module,
Ignition ON/Vehicle in Service Mode.
- Test for less than 1 V between the control circuit terminal 3 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K47 Rear Differential Clutch Control
Module.
- Go to next step: If between 5.6 - 6.4 V
3. Test for 4.9 - 5.3 V between the control circuit terminals listed below
and ground.
- Control Circuit Terminal 2
- Control Circuit Terminal 1
- If less than 4.9 V
- Ignition OFF, disconnect the X2 harness connector at the K47 Rear
Differential Clutch Control Module.
- Test for infinite resistance between the appropriate control circuit
terminal and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the control circuit terminal end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K47 Rear Differential Clutch Control
Module.
- Ignition OFF, disconnect the X2 harness connector at the K47 Rear
Differential Clutch Control Module,
Ignition ON/Vehicle in Service Mode.
- Test for less than 1 V between the appropriate control circuit terminal
and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K47 Rear Differential Clutch Control
Module.
- Go to next step: If between 4.9 - 5.3 V
4. Test or replace the Q49 Rear Differential Clutch Solenoid Valve.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Differential Carrier Assembly Replacement
- Control Module References for control module replacement, programming,
and setup.
READ NEXT:
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.
Diag
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.
Diag
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.
Diag
SEE MORE:
SPECIFICATIONS
FASTENER SPECIFICATIONS
Single Use Threaded Fastener/Component Tightening Specifications
NOTE:
All fasteners/components listed in this table MUST BE DISCARDED and replaced
with NEW
after removal.
Reusable Threaded Fastener Tightening Specifications
NOTE:
All fasteners listed in this
The lane departure warning system is a convenience feature that utilizes the
frontview camera module to
determine if the vehicle has unintentionally crossed a lane marking and issue a
warning. The frontview
camera module is located behind the windshield, looking out at the road ahead
and detectin