B0770 01
* Ignition ON
* System voltage 10-18 V
* Instrument panel lights not dimmed.
* Daylight running lights MUST be commanded ON.
* Circuit tested when the AWD indicator is commanded ON.
B0770 06
* Ignition ON
* System voltage 10-18 V
* Instrument panel lights not dimmed.
* Daylight running lights MUST be commanded ON.
* Circuit tested when the AWD indicator is commanded OFF.
Conditions for Setting the DTC
B0770 01
The TCCM detects 3.4 V or greater on the AWD indicator control circuit when the AWD indicator is commanded ON.
B0770 06
The TCCM detects 1.6 V or less for 1.5 seconds on the AWD indicator control circuit when the AWD indicator is commanded OFF.
Action Taken When the DTC Sets
Normal operation, the SERVICE 4WD indicator is not commanded ON. Driver is informed of fault via bulb inspection.
Conditions for Clearing the DTC
* The transfer case shift control module clears the DTC once the condition for setting the DTC is no longer present.
* A history DTC clears after 40 consecutive warm up cycles without a fault present.
* History DTCs can be cleared using a scan tool.
Diagnostic Aids
* A TRUE B+ has enough current to light a test light.
* A DIAGNOSTIC B+ is a low current circuit that DOES NOT have enough current to light a test light.
* A short to ground on the AWD indicator control circuit will cause the AWD indicator to remain ON at all times.
* An open or high resistance on the AWD indicator control circuit will cause the AWD indicator to be inoperative during the 2 second bulb
inspection.
* An open in the indicator dimming control circuit will cause the 2WD HI, AWD, 4WD HI and 4WD LO mode indicators to be inoperative
during the 2 second bulb inspection.
* EL-49741 - harness is a good source for 9 V.
* EL-49742 - harness is a good source for B+ and ground.
* With key REMOVED - opening a door puts a true B+ on the indicator dimming control circuit, TCSCS X1 pin 4. Other possible voltages are
listed below:
- Door open, key removed - indicator dimming control circuit voltage = true B+.
- Door open, key in, key OFF - indicator dimming control circuit voltage = true B+.
- Door open, key ON, engine OFF - indicator dimming control circuit voltage = diagnostic B+.
- All doors closed, key OFF - indicator dimming control circuit voltage = B+ (high current - enough to light a test light).
- All doors closed, key ON, engine OFF - indicator dimming control circuit voltage = diagnostic B+.
- Key ON, engine OFF. Place a shop light on the DRL sensor. When the DRL sensor commands the headlights OFF, the indicator dimming
control circuit voltage, TCSCS X1 pin 4, will go from a diagnostic B+ to a true B+.
Reference Information
Schematic Reference
Transfer Case Control Schematics (See: Transmission and Drivetrain/Transfer Case/Diagrams/Electrical Diagrams/MP 3023/3024-NQH - Transfer
Case)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
