Range And Mode Shifts

The process for performing all the range and mode shifts are the same. The following steps describe the process.

• Allow time for Selector Switch debounce; 250 msec +/-50 msec.
• Extinguish the source gear's LED while flashing desired, transfer case position's LED.
• Engage the shift motor for a maximum of 1 second +/-100 msec per 'D' channel transition in the destination gear's direction while monitoring the mode sensor channel transitions.
• Disengage the shift motor when the correct mode sensor code is recognized.
• Solidly illuminate the selected gear's LED.
• Transmit a bus message that the transfer case shift is complete.
• If the desired mode sensor code is not received after the shift timer expires (ie. a blocked or other condition exists), stop driving the motor and wait for 200 msec +/-50 msec. The shift motor is then reversed in the direction back toward the source gear for up to 1.0 seconds +/-100 msec, per 'D' channel. The TCCM waits for 2.0 seconds +/-50 msec. and repeats the attempt to shift to the desired position.

The exception to the preceding sequence is when a shift from 4L to 2WD/AWD is requested. If 2WD/AWD is requested from the 4L position, the transfer case is first driven to the 4H position. If the 4H position is reached, the transfer case is then driven back to the 2WD/AWD position and the shift is considered complete. If the transfer case does not reach any the 4H position, but is in the 2WD/AWD 'D' channel, or the 2WD/AWD between gear position on the 4H side of 2WD/AWD, the shift is also considered complete.