The Magna Powertrain model 3010 (MP 3010) transfer case (figure 1) has been the heart of GM’s four-wheel drive truck line since it was introduced in 2011 to replace the New Venture Gear transfer case system.
The MP 3010 transfer case is an electronically controlled, one-speed automatic, active transfer case, which provides three modes of operation: Auto 4WD, 4HI, and 2HI.
Software calibration allows the transfer case to use an on-demand torque biasing wet clutch system, along with additional features, such as a flexible adapt ready position and clutch torque preload levels.
The system is calibrated to provide 0-5 lb-ft of torque transfer during low speed, low engine RPM torque operation, and a predetermined higher torque transfer at speeds greater than 25 MPH.
In Auto 4WD mode, on non StabiliTrak equipped vehicles, the transfer case shift control module monitors the two front wheel speed sensors and the vehicle speed sensor to detect wheel slip.
On vehicles equipped with StabiliTrak, the transfer case shift control module monitors wheel speed through the four, wheel speed sensors in the antilock brake system (ABS) to detect wheel slip.
When the system detects wheel slip, the transfer case shift control module applies the torque-biasing wet clutch, located in the transfer case, transferring torque to the front wheels. Once it determines the wheels are no longer slipping, the transfer case shift control module disengages the clutch, which, in turn, disengages the front wheels.
This technology allows for speed-dependent torque transfer to enhance driving performance, prevent crow hopping or binding at low speeds, and enhance vehicle stability at higher speeds.
Now let’s see what controls the MP 3010 transfer case system.
System Control
The MP 3010 transfer case system is controlled by the transfer case shift control module. This module uses several components to monitor and control the transfer case operation, including:
- transfer case shift control switch
- two-/four-wheel drive increment sensor
- actuator shaft position sensor
- transfer case motor lock circuit
- two-/four-wheel drive actuator
- front axle actuator
- vehicle speed signal
…and torque demand information from the PCM or ECM.
Now let’s look at how the transfer case shift control module uses each of these components to control transfer case operation.
Module Operation
The transfer case shift control module — located to the right of accelerator pedal (figure 2) — uses the vehicle identification number (VIN) to determine the proper calibration for the transfer case control system.
The calibration is based on vehicle specific axle ratios, transmission types, tire sizes, and engine sizes. Modifications to axle ratios and tire sizes will interfere with transfer case operation.
The transfer case shift control module isn’t interchangeable with other vehicles and must be calibrated to the specific vehicle during replacement.
The module is capable of performing self-diagnosis and will light the “Service 4WD” message light — located on the driver’s information center (DIC) — if it encounters a problem. You can access the transfer case shift control module with a scan tool through the data link connector (DLC).
Transfer Case Control Switch
The MP 3010 transfer case control system uses a three-mode shift control switch — located on the instrument panel (figure 3) — to control transfer case operation. It’s a rotary switch with three positions: AUTO 4WD, 4HI and 2HI.
With the key on, the transfer case shift control module monitors the switch. As with most GM transfer case control systems, if the module receives a request from the switch to change range, and all the parameters are met, the module will attempt to shift the transfer case to the requested range.
The module will flash the requested gear range indicator light as it attempts to shift the transfer case into the requested range. Once the transfer case has shifted into the requested range, the module will turn the range indicator light on, indicating that it’s in the requested range.
If the transfer case can’t engage the requested range, the module will return the transfer case to its previous range and may set code C0387 — unable to complete shift — in memory.
Additional Components
Two/Four Wheel Drive Incremental Sensor — is located within the transfer case actuator motor and can’t be serviced separately. The sensor converts the transfer case shift lever shaft position into an electrical signal. The module uses this signal to determine what range the transfer case is in.
Actuator Shaft Position Sensor — The module uses signal from the actuator shaft position sensor — located externally (figure 4) — along with the signal from the 2/4 wheel drive incremental sensor, to determine transfer case range position in degrees.
Transfer Case Motor Lock Circuit — is located in the two/four wheel drive actuator (refer to wiring schematics). The circuit locks the two-/four-wheel drive actuator motor in position. When the lock circuit energizes, it allows the transfer case actuator motor to turn. When the lock circuit isn’t energized, it prevents the transfer case actuator motor from turning, locking it in place.
Two/Four Wheel Drive Actuator — This assembly (figure 5) consists of a permanent magnet DC reversible motor and gear reduction assembly, located on the transfer case. When activated, the actuator turns the shift lever in the transfer case assembly. The actuator is controlled by a PWM signal from the module and it allows the transfer case to shift between 2HI and 4HI ranges.
Front Axle Actuator — an electronically controlled actuator, controlled by the module, that engages the front axle (figure 6).
Vehicle Speed
The MP 3010 transfer case control system monitors the vehicle’s speed to control the transfer case operation. The vehicle speed sensor is located on the transfer case (figure 7), creating a signal based on output shaft RPM. The module uses this signal to determine vehicle speed.
The VSS sensor is a permanent magnet (PM) generator that produces an AC signal. The signal voltage and frequency increase with vehicle speed.
The VSS signal from this sensor is a direct input to the powertrain control module (PCM) or engine control module (ECM) (figures 8 and 9), depending on application.
The PCM or ECM combines both the VSS input and the ABS wheel speed input to calculate actual vehicle speed. This calculated vehicle speed is then sent to the transfer case shift control module via the GM LAN serial data line.
Now that we’ve seen what controls the MP 3010 transfer case system, watch for the next installment of Keep Those Trannys Rolling, where we’ll walk through the diagnostic routines needed to keep this MP 3010 transfer case rolling down the road.
