GMC C Series 1993, Repair Manual

Page: 88 / 264

BEAR AXLE CONTROLS 4B2-1
SECTION 4B2
REAR AXLE CONTROLS
NOTICE: When fasteners are re m o v e d a lw a y s re in stall them at the same location from which they were
removed. If a fastener needs to be replaced, use the co rre ct p a rt num ber fastener fo r that application. If
the correct p a rt num ber fastener is n o t available, a fastener o f equal size and strength (o r stronger) m ay
be used. Fasteners that are n ot reused, and those requiring thread locking com pound w ill be called out.
The correct torque value m u st be used when installing fasteners that require it. If the above conditions
are n o t followed, p a rts o r system damage could result, i
CONTENTS
SUBJECT PAGE
General Description.... ........... ................;........................ .................................... ............... ...................... ,.........4B2-1
Two-Speed Axle Electric Shift Unit ..... ................... ....... ................ .... .........4B2-1
Unit Repair......................... ............. ...;.......... ................ ..................... ..................•,..................... ........................ 4B2-1
Disassembly.......,........................ ................................... ................ ................... ................................................ 4B2-1
Assembly.......................................... ............. .............................................. ................. .......... ......................... ...4b2-2
General Description........................... ........... ............... ................ ....;............................ ............... ...................... 4B2-3
Two-Speed Axle Air Shift Unit................ ......................... ................ ......... .................. .................... .............4B2-3
Unit Repair..................... ....................... ..................................4........ .................................. ....................................4B2-4
Disassembly.................. ................ ............. ............. ............................ .......... ............. ...................................... 4B2-4
Assembly....................................................... ............... .....;.................................**.,.*•............................ .
4B2-4
Specifications.................................................. ............................. ....................................................................... . 4B2-6
Fastener Tightening Specifications............................ .............. ........................... ........... .........4B2-6
GENERAL DESCRIPTION
TWO-SPEED AXLE ELECTRIC
SHIFT UNIT
The electric shift unit consists of a pre-loading spring
actuator that is driven by an electric motor. When the
axle range switch is moved into either “HIGH” or
“LOW” position, the electric motor compresses the
spring actuator until a limit switch stops the motor.
When the driving load is removed from the axle, the
compressed spring will shift the axle.
UNIT REPAIR
DISASSEMBLY
Remove or Disconnect (Figures 1 and 2)
7. Motor (9). :
8. Four screws (16).
9. Housing (6).
10. Slider block (14).
1. Four hex head screws (2).
2. Cover (1). .
3. Circuit board wires (18, 19, and 20) from the cover.
4. Nut (4).
5. Circuit board (3) and washer (5).
A. Lift the circuit board.
B. Disconnect the black wire (21) from the: circuit
board.
6. Three screws (10).
NOTICE: The sealing surfaces on the cover
(1), housing, and m o to r (9) are bonded with
an RTV type sealer. These parts could allow
m oisture to enter o r be damaged i f care is
not exercised during disassembly.
11. Nut (13).
12. Shaft and gear (11).
13. Cam pins (8) from inside the, housing.