C1407

C1407- TRANSFER CASE BRAKE CONTROL CIRCUIT LOW





When Monitored:
Ignition on. Battery voltage between 9 and 16 volts.

Set Condition:
FCM detects low voltage for 2 seconds on the Shift Motor Brake Signal circuit with the feature off.

Possible Causes
- INTERMITTENT CONDITION
- (T300) SHIFT MOTOR BRAKE SIGNAL CIRCUIT OPEN
- (T300) SHIFT MOTOR BRAKE SIGNAL CIRCUIT SHORTED TO GROUND
- SHIFT MOTOR/MODE SENSOR ASSEMBLY
- FRONT CONTROL MODULE

Theory of Operation
The purpose of the Shift Motor Brake is to provide a means of physically holding the Transfer Case actuator in place.

The Shift Motor Brake consists of a solenoid which releases the Transfer Case actuator when current is applied.

The FCM applies a ground to the Shift Motor Brake to release the Transfer Case actuator:
1. Any time a shift is taking place.
2. For a predetermined amount of time before and after the shift based on a timer.
3. Any time a Shift Motor Brake DTC is active.

No shifting will take place if either a Shift Motor Brake DTC is present or the Shift Motor Brake timer is active.

While the timer is active, or if a Shift Motor Brake short to ground DTC is present, static braking is implemented to keep the actuator in place.

Diagnostic Test
1. T-CASE BRAKE ACTUATION





Ignition on, engine not running.
With the scan tool, actuate the T-Case Brake.
With the scan tool, monitor the T-Case Brake State.
Does the T-Case Brake State change properly as the circuit is actuated on and off?
Yes >>Go to 5
No >>Go to 2

2. SHIFT MOTOR BRAKE SIGNAL CIRCUIT SHORTED TO GROUND





Ignition off.
Disconnect the Shift Motor/Mode Sensor Assembly connector.
Measure the resistance between ground and the (T300) Shift Motor Brake Signal circuit.
Is the resistance below 5.0 ohms?
Yes >>Repair the (T300) Shift Motor Brake Signal circuit for a short to ground.
Perform the TRANSFER CASE VERIFICATION TEST VER 1. Transfer Case Verification Test
No >>Go to 3

3. SHIFT MOTOR/MODE SENSOR ASSEMBLY





Ignition on, engine not running.
With the scan tool, actuate the T-Case Brake.
Using a 12-volt test light connected to 12-volts, check the (T300) Shift Motor Brake Signal circuit.
Does the test light turn on and off properly as the circuit is actuated on and off?.
Yes >>Replace the Shift Motor/Mode Sensor Assembly. Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Go to 4

4. FRONT CONTROL MODULE





Ignition off.
Disconnect the Power Distribution Module C2 connector.
Measure the resistance of the (T300) Shift Motor Brake Signal circuit.
Is the resistance below 5.0 ohms?
Yes >>Check the (T300) circuit from the FCM connector to the PDM connector. If OK, replace the Front Control Module in accordance with the Service information. If not OK, replace the Power Distribution Module.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Repair the (T300) Shift Motor Brake Signal circuit for an open.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.

5. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Were any problems found?
Yes >>Repair as necessary.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Test complete.