LAMP STRATEGY
The following strategy for the FCM controlled transfer case system uses the instrument cluster VF display’s 4LOCK,
4LO, Service 4WD, and Mode Switch Transfer Case Neutral LED. Flashing any of the lamps or LED is accom-
plished at a 2Hz rate.
NOTE: There is no lamp for the AWD position. If no 4WD system message icons are illuminated in the
instrument cluster, the operator is to assume that the transfer case is in the AWD position.
•
AWD to 4LO - Successful shifts will flash 4LO during a shift, then after the 4LO position has been met, display
the 4LO lamp solid. In the blocked condition, flash the 4LO lamp during the 5 Phase 1 shift attempts. After 5
unsuccessful attempts, the transfer case remains in AWD and no lamps are illuminated. When shift conditions
are not met, no shift attempts are made and the 4LO lamp is flashing.
•
AWD to 4LOCK - Successful shifts will flash 4LOCK during a shift, then after the 4LOCK position has been
met, display the 4LOCK lamp solid. In the blocked condition, flash the 4LOCK lamp during the 5 Phase 1 shift
attempts. After 5 unsuccessful attempts, the transfer case remains in AWD and no lamps are illuminated.
When shift conditions are not met, no shift attempts are made and the 4LOCK lamp is flashing.
•
4LOCK to 4LO - Successful shifts will turn off the 4LOCK lamp and flash 4LO during a shift, then after the 4LO
position has been met, display the 4LO lamp solid. In the blocked condition, turn off 4LOCK and flash the 4LO
lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in 4LOCK
and the 4LOCK lamp turns on solid. When shift conditions are not met, the 4LOCK lamp remains illuminated
solid and the 4LO lamp is flashing.
•
4LOCK to AWD - Successful shifts will flash the 4LOCK lamp during a shift, then after the AWD position has
been met, turn off the 4LOCK lamp. In the blocked condition, flash the 4LOCK lamp during the 5 Phase 1 shift
attempts. After 5 unsuccessful attempts, the transfer case remains in 4LOCK and the 4LOCK lamp turns on
solid. When shift conditions are not met, no shift attempts are made and the 4LOCK lamp is flashing.
•
4LO to AWD - Successful shifts will flash the 4LO lamp during a shift, then after the AWD position has been
met, turn off the 4LO lamp. In the blocked condition, flash the 4LO lamp during the 5 Phase 1 shift attempts.
After 5 unsuccessful attempts, the transfer case remains in 4LO and the 4LO lamp turns on solid. When shift
conditions are not met, no shift attempts are made and the 4LO lamp is flashing.
•
4LO to 4LOCK - Successful shifts will turn off the 4LO lamp and flash 4LOCK during a shift, then after the
4LOCK position has been met, display the 4LOCK lamp solid. In the blocked condition, turn off 4LO and flash
the 4LOCK lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains
in 4LO and the 4LO lamp turns on solid. When shift conditions are not met, the 4LO lamp remains illuminated
solid and 4LOCK is flashing.
•
AWD to NEUTRAL - Successful shifts have no lamps illuminated, then after the NEUTRAL position has been
met, display the NEUTRAL LED solid. In the blocked condition, no lamps are illuminated during the 5 Phase
1 attempts. After 5 unsuccessful attempts, the transfer case remains in AWD and no lamps are illuminated.
When shift conditions are not met, flash the NEUTRAL lamp while the push button is depressed.
•
4LOCK to NEUTRAL - Successful shifts have no lamps illuminated, then after the NEUTRAL position has been
met, display the NEUTRAL LED solid. In the blocked condition, no lamps are illuminated during the 5 Phase
1 attempts. After 5 unsuccessful attempts, the transfer case remains in 4LOCK and the 4LOCK lamp is illu-
minated. When shift conditions are not met, flash the NEUTRAL lamp while the push button is depressed.
•
4LO to NEUTRAL - Successful shifts have no lamps illuminated, then after the NEUTRAL position has been
met, display the NEUTRAL LED solid. In the blocked condition, no lamps are illuminated during the 5 Phase
1 attempts. After 5 unsuccessful attempts, the transfer case remains in 4LO and the 4LO lamp is illuminated.
When shift conditions are not met, flash the NEUTRAL lamp while the push button is depressed.
•
NEUTRAL to AWD - Successful shifts have no lamps illuminated, then after the AWD position has been met,
no lamps are illuminated. In the blocked condition, no lamps are illuminated during the 5 Phase 1 attempts.
After 5 unsuccessful attempts, Phase 2 shifting will continue until the transfer case is in the AWD or 4LO posi-
tion. If the final position is AWD, no lamp is illuminated, if the final position is 4LO, illuminate the 4LO lamp.
When shift conditions are not met, flash the 4LOCK and 4LO lamps and the NEUTRAL LED remains solid
while the push button is depressed,
•
Neutral to 4LOCK - Successful shifts will flash the 4LOCK lamp during a shift, then after the 4LOCK position
has been met, display the 4LOCK lamp solid. In a blocked condition, the 4LOCK lamp will flash during the 5
Phase 1 attempts. After 5 unsuccessful attempts, continue to flash the 4LOCK, Phase 2 shifting will continue
until the transfer case is in the AWD or 4LO position. If the final position is AWD, turn off the 4LOCK lamp, if
HB
ELECTRONIC CONTROL MODULES - SERVICE INFORMATION
8E - 213