Chevrolet 10 Series 1968, Service Manual, Page: 685 / 713

ACCESSORIES 15-11
CRUISE MASTER SYSTEM CHECKS
Problem Cause Correction
Will not engage-System
Inoperative
Brake Switch C ircu it Open
Clutch Switch C ircu it Open
Check connections- adjust or replace switch.
Refer to Electrical Check Out.
Fuse blown
Replace fuse—if it blows again, check for:
1. Engage Switch stuck in the center of travel—
Refer to Electrical Check Out.
2. Incorrect w iring—Refer to Electrical
Check Out.
3. Short to ground-Refer to Electrical
Check Out.
Make necessary corrections.
Defective Engage Switch
Replace as needed-Refer to Electrical Check Out.
Vacuum leak in Servo and/or Brake Switch and
connecting lines. Vacuum hose not connected
to vacuum switch.
Vacuum test and repair or replace as needed.
Refer to Servo and Vacuum System Check Out.
Vacuum release switch misadjusted (always open) Readjust switch.
Crossed vacuum & air hose at regulator
Reroute hoses.
Open in wiring harness
Repair or replace as needed.
Defective Regulator
Replace Regulator
Does not cruise at engagement
speed
Orifice Tube misadjusted
Adjust as required.
System hunts, pulses or surges Bead Chain loose
Tighten Bead Chain.
Hoses reversed at Servo
Make necessary corrections.
Kinked or deteriorated hoses (air leak) Repair or replace.
Dirty Air Filter
Service as required.
Defective and/or improperly positioned Drive Cables
and/or Casing Assemblies
Repair or replace as needed.
Defective Regulator
Replace Regulator.
System does not disengage—with
brake pedal or with clutch
pedal
Brake clutch, and/or Vacuum Switch mis-adjusted
or defective
Adjust or replace as required. Refer to Servo
and Vacuum System Check Out and Electrical
Check Out.
Red wires [which should be connected to the pedal
switch(es)] connected to the fuse block
Reroute wires to stoplight switch.
System steadily accelerates or
applies
iu ii
throttle when
Hoses interchanged at Servo Manifold vacuum
connected directly to outboard tube of Servo.
Reroute hose to Regulator vacuum valve.
engaged
Defective Regulator
Replace Regulator.
Pinched or plugged air hose that is connected to
the outboard tube of Servo.
Free or replace hose.
Cannot adjust speed downward
with Engage Button
Defective Engagement Switch or Wiring
Replace as needed. Refer to Electrical Check Out.
Does not engage or engages lower
than limits referred to in
"Driver Operation"
Defective Regulator Replace Regulator.
Slow throttle return to idle after
brake is depressed.
Pinched air hose at vacuum release switch Free or replace hose.
System operates correctly, but
constant vacuum bleed when
system is disengaged.
Crossed vacuum hoses at regulator
Reroute hoses.
High engine idle speed-indepen­
dent of carburetor adjustments.
Constant air bleed through
system.
Tight Servo Chain Loosen chain adjustment.
Manifold vacuum connected directly to center tube
of Servo
Reroute hose.
Constant drain on battery. Power lead connected to "Fused Battery" terminal
of fuse block
Reroute to "Fused Ign." terminal.
System can be engaged at idle by
depressing switch, but will drop
out when switch is released.
Solenoid can be heard when
switch is depressed when the
vehicle is standing still.
Wires reversed at regulator Reverse w ire s-Se e Fig. 10.
CHEVROLET TRUCK SERVICE MANUAL