Download DTC C0323 T-Case Lock Circuit Low

1998 Chevrolet/Geo Tahoe - 4WD
DTC C0323 T-Case Lock Circuit Low
Circuit Description
The transfer case shift control module controls the transfer case lock solenoid.
The lock is energized (locking action released, grounding CKT 1569) during gear shifts and in AUTO (Adapt) mode of
operation. When power or ground is removed from the lock solenoid, (locking action applied), the transfer case motor
is prevented from moving. In this manner, the system is capable of providing a 4H and 4L lock-up without the need of
additional vehicle power to hold the transfer case in these positions.
This DTC detects an open lock solenoid coil, CKT 1569 open, open feed (CKT 1640) to the solenoid.
Conditions for Setting the DTC
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The system will try to turn the lock solenoid off by opening the ground circuit.
If the module is unable to de-energize the solenoid, the system will not attempt to de-energize the solenoid again
during that ignition cycle.
Auto transfer case lock output reads back as a low voltage when a high voltage is expected.
Action Taken When the DTC Sets
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All shifting will be disabled.
The SERVICE indicator (AWD/4WD) lamp will be latched on for the remainder of the current ignition cycle.
Conditions for Clearing the DTC
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The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
A history DTC will clear after 100 consecutive ignition cycles without a fault present.
History DTCs can be cleared using a scan tool.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. This step determines if battery voltage exists on circuit 1640.
4. This step determines if the internal resistance of the encoder motor lock circuit is within specified limits.
6. This step determines whether circuit 1569 is open.
Step
1
2
3
4
5
6
7
Action
Was the Transfer Case Diagnostic System Check
performed?
Value(s)
Yes
--
Go to Step 2
No
Go to Transfer Case
Diagnostic System
Check
Go to Step 4
Go to Step 3
Go to Step 11
--
Go to Step 5
Go to Step 7
Is the resistance reading less than the specified value?
Measure the resistance between transfer case shift control
module connector C1 terminal E1 and the transfer case
encoder motor connector C1 terminal D.
0-5 ohms
Go to Step 8
Go to Step 6
Is the resistance reading within the specified values?
Replace the transfer case encoder motor (lock solenoid).
Refer to Motor/Encoder Replacement .
Go to Step 10
Go to Step 9
Go to Step 11
--
1. Turn the ignition to the OFF position.
2. Disconnect the transfer case encoder motor harness.
3. Connect a J 39200 Digital Multimeter DMM from
the encoder motor harness connector C1 terminal C 9-14 V
to ground in order to measure the voltage.
Is the voltage with in the specified values?
Repair an open in CKT 1640 between splice S236 and the
transfer case encoder motor. Refer to Wiring Repairs in
Wiring Systems.
Are the repairs complete?
Use a J 39200 DMM in order to measure the resistance
across the encoder motor lock circuit.
Is the resistance reading within the specified values?
1. Disconnect the transfer case shift control module
connectors.
2. Use the J 39200 DMM in order to measure the
resistance between transfer case shift control
module connector C1 terminal E1 and ground.
Is the repair completed?
-2080 ohms
OL
--
8
9
10
Repair an short to ground in CKT 1569. Refer to Wiring
Repairs in Wiring Systems.
Are the repairs complete?
Repair an open in CKT 1569. Refer to Wiring Repairs in
Wiring Systems.
--
Go to Step 11
--
Are the repairs complete?
Replace the transfer case shift control module. Refer to
Transfer Case Shift Control Module Replacement .
--
Go to Step 11
--
Is the repair completed?
Reconnect all ATC system components, make sure all the
components are properly mounted.
--
Go to Step 11
--
Have all the ATC components been reconnected and
properly mounted?
Clear all the ATC DTCs.
--
Go to Step 12
--
Are all the ATC DTCs cleared?
--
Go to Transfer Case
Diagnostic System
Check
--
11
12