1999 GMC C-SERIES clutch

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2-36 Cruise Control (If Equipped)
With cruise control, you can
maintain a speed of about
30 mph (48 km/h) or more
without keeping your foot
on the accelerator. Cruise
control does not work at
speeds below about 30 mph
(48 km/h).
If you have an automatic transmission and you apply
your brakes, the cruise control will shut off.
If you have a manual transmission and you apply your
brakes or push the clutch pedal, the cruise control will
shut off.CAUTION:

Cruise control can be dangerous where you
can't drive safely at a steady speed. So,
don't use your cruise control on winding
roads or in heavy traffic.

Cruise control can be dangerous on
slippery roads. On such roads, fast changes
in tire traction can cause needless wheel
spinning, and you could lose control. Don't
use cruise control on slippery roads.
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2-39
Using Cruise Control on Hills
How well your cruise control will work on hills depends
upon your speed, load and the steepness of the hills.
When going up steep hills, you may want to step on the
accelerator pedal to maintain your speed. When going
downhill, you may have to brake or shift to a lower gear
to keep your speed down. Of course, applying the brake
or clutch takes you out of cruise control. Many drivers
find this to be too much trouble and don't use cruise
control on steep hills.
Ending Cruise Control
There are different ways to turn off the cruise control:

Step lightly on the brake pedal.

Push the clutch pedal, if you have a
manual transmission.

Move the cruise switch to OFF.
Erasing Speed Memory
When you turn off the ignition, your cruise control set
speed memory is erased.Trailer Brake Hand Control Valve
(Option)
If your vehicle has this feature, it is mounted on the
steering column.
This control lets you apply the trailer brakes without
applying the tractor brakes. You can apply the trailer
brakes a little or apply them all the way if you have to.
Use this control only when you're driving. Don't use it
for parking or to hold the rig on a hill.
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4-31
Power Take-Off (PTO) (If Equipped)
Before using a PTO, refer to the body builder's or
operator's instructions.
To engage a PTO:
1. Make sure the vehicle is stopped.
2. Shift the transmission into NEUTRAL (N) or
PARK (P), if equipped.
3. The brake or clutch pedal must be pressed and
released once before PTO can be enabled. Do not
hold the brake or clutch pedal down.4. The cruise control switch must be in ON prior to
engaging the PTO switch to enable PTO operation.
This sets the PTO base engine idle at 1200 rpm.
5. Use SET/COAST to change the engine speed to the
lower preset value of 1400 rpm. Use
RESUME/ACCEL to change the engine speed to the
upper preset value of 1800 rpm. You may toggle
between upper and lower by moving the switch
between SET/COAST and RESUME/ACCEL.
The PTO will become inoperative when any of the
conditions are changed or the CHECK GAGES light
comes on.
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5-33
5. Then replace the pressure cap. Be sure the arrows on
the pressure cap line up like this.
Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not fully engaged. This
improves fuel economy and reduces fan noise. Under
heavy vehicle loading, trailer towing and/or high outside
temperatures, the fan speed increases when the clutch
engages. So you may hear an increase in fan noise.
This is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
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6-12 Tampering With Noise Control
System Prohibited
Federal law prohibits the following acts or the
causing thereof:
1. The removal or rendering inoperative by any person,
other than for purposes of maintenance, repair or
replacement, of any device or element of design
incorporated into any new vehicle for the purpose of
noise control, prior to its sale or delivery to the
ultimate purchaser or while it is in use; or
2. The use of the vehicle after such device or element
of design has been removed or rendered inoperative
by any person.
Among those acts presumed to constitute tampering are
the acts listed below.
Insulation:

Removal of the noise shields or any
underhood insulation.Engine:

Removal or rendering engine speed governor (if
equipped) inoperative so as to allow engine speed to
exceed manufacturer specifications.
Fan and Drive:

Removal of fan clutch (if equipped) or rendering
clutch inoperative.

Removal of the fan shroud (if equipped).
Air Intake:

Removal of the air cleaner silencer.

Reversing the air cleaner cover.
Exhaust:

Removal of the muffler and/or resonator.

Removal of the exhaust pipes and exhaust
pipe clamps.
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6-37 Clutch Pedal Free Travel
If you have a manual transmission, your clutch will need
adjustment when pedal free travel gets down to about
1 1/4 inch (32 mm), as measured at the clutch pedal pad.
You should have 1 1/2 to 2 inches (38 to 51 mm) of
clutch pedal free travel. Your Maintenance Schedule has
more on this.
If your clutch ever needs service, be sure to use only
genuine GM clutch replacement parts.
Chassis Lubrication
Your Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see your Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.
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6-39
ITEM NO. ITEM REMARKS
1 Brake Camshaft
, Brake Caliper
Rails (If Equipped)$One fitting each (apply sparingly). For caliper rails,
apply Aero Shell #5 Lubricant.
2 Steering Column Slip Joint* One fitting.
3 Steering Drag Link Ends One fitting at each end.
4 Steering Column U
-Joints One fitting each joint.
5 Pivot Points and Hinges Apply chassis lubricant.
6 Slack Adjuster
One fitting.
7 Brake Cam Roller Pins at interface
of pin and shoe
Apply engine oil.
8 Front Steering Knuckles One fitting each side, lower bushing (hand
-operated
grease gun only). Hand
-pack upper bearing.
9 Front Wheel Bearings Hand
-pack or lubricate.
10 Steering Tie Rod Ends One fitting each end.
11 Spring Slip Pads*
(Multi
-Leaf Only)Apply chassis lubricant.
12 Clutch Release Bearing* Cup or fitting.
13 Battery Terminal
(except ªSTº type)Keep coated with petroleum jelly.
14 Parking Brake Bell Crank*$ One fitting.
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6-70
Name Circuits Protected
HYD BRK Brake Pump Motor Relay
HYD BRK Brake Alarm ModuleName Circuits Protected
B/U IGN3 Fuel Filter Relay, Blower Motor
Relays, ABS Power Relay,
Back
-Up Lamps, Auxiliary Wiring
Relay, IGN 3 Relay, Power
Window Relay, Vehicle Interface
Module, Transmission
Temperature Gage
STOP Stoplamps
WASH/WIPE Windshield Wipers/Washer,
Accessory Relay
DOME/PNL Dome Lamp, Radio Receiver,
Instrument Panel Lights,
A/C Controller,
Headlamp/Seatbelt Module
BLOWER Blower Motor
A/C A/C Clutch Compressor,
A/C Controller
TRN/HAZ Turn Signals, Hazard Flashers
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