GMC 2003 C4C042 Owner's Manual page 365

(26) = Evaporative Control System Service
(if equipped): Check all fuel and vapor lines and hoses
for proper connections and correct routing (or every
24 months, whichever occurs first). Replace parts
as needed.
(28) = Replace spark plugs. Inspect wires for damage.
Check the wire boot and boot heat shield fit at spark
plugs and coil. Replace parts as needed.
(30) = Check the fuel tank, fuel cap and fuel lines for
damage which could cause leakage. Inspect fuel cap for
correct sealing ability and any indications of damage.
Check fuel cap gasket for even filler neck imprint.
Replace parts as needed.
(31) = Check EGR system as described in the
service manual. See "Service and Owner Publications"
in the Index.
(32) = Inspect Electronic Vacuum Regulator Valve
(EVRV) filter for excessive contamination or plugging.
If needed, clean filter with solution of soap and water,
let dry and install.
(35) = Drain, flush and refill cooling system. See
"Recommended Fluids and Lubricants" in the Index for
what to use. Inspect hoses. Clean radiator, condenser,
pressure cap and neck. Pressure test cooling system and
pressure cap. For Caterpillar
refer to the Caterpillar Diesel Engine Operation &
Maintenance Manual for coolant recommendations and
change intervals.
(37) = Rear axle service: Change the lubricant. See
"Recommended Fluids and Lubricants" in the Index.
(38) = Front axle service: Re
roller bearing.
R
diesel engines, always
-
pack upper kingpin
7-19