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 C0400: Transfer Case Clutch Calibration Resistor CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Invalid |
|---|---|---|---|---|
Transfer Case Clutch Calibration Resistor Circuit | C0400 | C0400 | C0400 | C0400 |
Circuit/System Description
A transfer case will be equipped with one of nine different value transfer case resistors. The resistor value the unit is equipped with is dependent upon manufacturing tolerances and is a result of end of line testing at the manufacturer. A 5-volt reference is supplied to the resistor, and then it is read back via the clutch resistor signal circuit giving the module the voltage indicating what resistor value is present. Having the wrong resistor may cause the system to be less responsive to certain driving situations and also could damage the front axle. Depending on the resistor value used a customer may never know the system is not performing at optimum efficiency.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | System voltage is 9-16 volts. |
Conditions for Setting the DTC
DTC C0896 is not set.
Action Taken When the DTC Sets
| • | System performance may be affected. |
| • | No DIC messages will be displayed. |
Conditions for Clearing the DTC
| • | The transfer case shift control module clears the DTC if the conditions for setting the DTC are not currently present. |
| • | A history DTC clears after 40 consecutive warm up cycles without a fault present. |
| • | All DTCs can be cleared using a scan tool. |
| • | Clearing DTCs will also clear failure records. |
Diagnostic Aids
| • | Check failure records for further information on the conditions present when this DTC set. |
| Important: Having an incorrect resistor value will not disable the AWD system and will likely not be noticed by the driver. However this fault should be addressed, as this will optimize system performance. |
| • | This fault will likely not be noticed by the driver; however you can address this fault by looking at the clutch resistor value on the scan tool via the scan tool data list. The voltages should never be below 0.20 volts or above 4.60 volts. |
| • | Check inline connector X103 for bent pins, corrosion, or other damage. |
| • | Check for bent pins inside the resistor. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
The clutch coil resistor can be checked by measuring the resistance of the resistor with a DMM by putting one lead on pin B and the other on pin A, the correct resistance is embossed in the resistor. If the system is operating normally you should see a voltage range of 0.20-4.60 volts on the clutch resistor value via the scan tool data list. The value for the 5-volt reference circuit should be 4.8-5.0 volts. Further explanation is given in component testing. Should you see a voltage out of range you should check the 5-volt reference circuit and the signal circuit for an open, high resistance, short to voltage, or short to ground.
| ⇒ | See component testing for further direction. |
Component Testing
Clutch Resistor values can vary up to 3 percent and not set a DTC. Resistor values falling within the dead band area will set this DTC.
Clutch resistors vary depending on clutch stack up during manufacture. View the clutch resistor values on the scan tool this will allow you to properly diagnose the circuit. A system operating within the suggested voltage range will be operating as designed.
Clutch Style | Ohms | Suggested Voltage | GM Part Number |
|---|---|---|---|
Clutch Style 1 | 0.115k ohms | 4.4-4.6 volts | 19206436 |
Clutch Style 2 | 0.255k ohms | 3.9-4.1 volts | 19206437 |
Clutch Style 3 | 0.453k ohms | 3.3-3.5 volts | 19206438 |
Clutch Style 4 | 0.715k ohms | 2.8-3.0 volts | 19206439 |
Clutch Style 5 | 1.15k ohms | 2.2-2.4 volts | 19206440 |
Clutch Style 6 | 1.82k ohms | 1.7-1.9 volts | 19206441 |
Clutch Style 7 | 3.16k ohms | 1.1-1.3 volts | 19206442 |
Clutch Style 8 | 7.32k ohms | 0.56-0.70 volts | 19206443 |
Clutch Style 9 | 12.70k ohms | 0.20-0.39 volts | 19206444 |
Dead Bands | Volts |
|---|---|
Dead Band 1 | >4.6 volts |
Dead Band 2 | >4.1-<4.4 volts |
Dead Band 3 | >3.5-<3.9 volts |
Dead Band 4 | >3-<3.3 volts |
Dead Band 5 | >2.4-<2.8 volts |
Dead Band 6 | >1.9-<2.2 volts |
Dead Band 7 | >1.3-<1.7 volts |
Dead Band 8 | >0.7-<1.1 volts |
Dead Band 9 | >0.39-<0.56 volts |
Dead Band 10 | <0.20 volts |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TCSCM replacement, setup, and programming
