Daewoo MUSSO Service Manual page 1219

5D2-10 TRANSFER CASE (TOD)
Electric Shift System Operation
The Electric Shift System is responsible for changing the Transfer Case gear ratio by controlling the electric shift
motor. The TCCU monitors the 4H/4L switch, neutral switch, speed sensors, position encoder, and ignition switch.
A range change is initiated when
1. The 4H/4L Switch is changed from 4H to 4L or from 4L to 4H.
2. The motor position (as indicated by the position encoder) does not match the 4H/4L Switch immediately after the
ignition is turned on.
1. Shift Criteria
When a range change is initiated a Diagnostic Test will be completed on the motor, speed sensors, and position
encoder. If the Diagnostic Test fails, the shift will not be attempted. If all components are operating properly, the
TCCU will attempt a range change after the following shift criteria are met:
a. The transmission is in neutral for 2 seconds after the shift is requested.
b. Both propshaft speeds are below 87 rpm (2580 pulses/minute).
If the transmission is taken out of neutral before 2 seconds has elapsed, or either propshaft speed increases
above the limit, the shift will be suspended and the 4L Indicator will continue to blink until the criteria are met again
or the 4H/4L Switch is returned to the original position.
2. Range Change
When the shift criteria are met, the motor is rotated in the appropriate direction (as determined by the selector
switch) until one of the following occurs:
a. The motor reaches its destination.
b. The motor is on for 5 seconds without reaching its destination. The shift has failed and the TCCU will respond
as default mode.
c. A fault occurs with either the motor or position encoder. Refer to the diagnosis requirement.
When the motor is energized, the Ignition, 4H/4L Switch, propshaft speeds, and transmission neutral inputs are
ignored.
3. Indicator Function
Once a range change has been initiated the 4L Indicator will begin to blink at a rate of 0.3 seconds on, 0.3
seconds off until the shift is completed or canceled.
If a successful shift has been completed, the 4L Indicator will be illuminated if the motor is in Low and it will be
turned off if the motor is in High.
4L Indicator illuminates as below figure.
4H ® 4L
·
@ : shift is completed
4L ® 4H
·
@ : shift is completed