1993 CHEVROLET DYNASTY sensor

REMOVE (1) Hold system relay with one hand, while pulling
strait down on the wiring harness connector. Until
connector is free from the relay (do not twist the
connector). (2) Remove screw (Fig. 6) holding the system relay
and bracket to the CAB bracket. Then remove the
system relay and mounting bracket assembly from
the CAB bracket.
INSTALL (1) Mount the system relay and its mounting
bracket assembly to the CAB mounting bracket, with
the mounting screw (Fig. 6). (2) Holding the system relay with one hand, push-
ing the wiring harness connector strait onto the ter-
minals of the relay. Make sure connector is fully
seated onto terminals of the system relay and the
lock on the wiring harness connector is fully engaged
with the relay. (3) Road test vehicle to verify correct operation of
the vehicles's Antilock brake system.
REMOVE/INSTALL PUMP MOTOR RELAY
Find location of Antilock Pump Motor Relay (Fig. 7
& 8), depending on whether the vehicle being ser-
viced has or does not have a power distribution cen-
ter PDC. (1) Hold the Antilock pump motor relay with one
hand, while pulling wiring harness relay connector
strait off the relay terminals. (2) Remove the pump motor relay assembly from
the vehicle. (3) Installation is done in the reverse order off re-
moval. Be sure that the wiring harness connector is
fully seated onto the terminals of the Pump Motor
Relay.
WHEEL SPEED SENSORS
INSPECTION
Inspect tonewheel for missing or broken teeth, this
can cause erratic sensor signals. Tonewheel should show no evidence of contact with
the wheel speed sensor. If contact was made, deter-
mine cause and correct. Excessive runout of the tonewheel can cause er-
ratic wheel speed sensor. Replace assembly if runout
exceeds approximately 0.25 mm (0.010 inch).
FRONT WHEEL SPEED SENSOR (FIG. 9)
REMOVAL
(1) Raise vehicle and remove wheel and tire as-
sembly. (2) Remove screw from grommet retainer clip that
holds the grommet into fender shield (Fig. 9). (3) Remove the 2 screws that fasten the sensor
routing tube to the frame rail.
Fig. 6 System Relay And Bracket Removal
Fig. 7 Pump Motor Relay Location On AA Body W/O Power Distribution Center
Fig. 8 Pump Motor Relay Location On AJ Body WithPower Distribution Center
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 43

(4) Carefully, pull sensor assembly grommet from
fender shield. (5) Unplug speed sensor connector from vehicle
wiring harness. (6) Remove the sensor assembly grommets from
the retainer brackets. (7) Remove sensor head screw.
(8) Carefully, remove sensor head from steering
knuckle. If the sensor has seized, due to corrosion,
DO NOT USE PLIERS ON SENSOR HEAD. Use
a hammer and a punch and tap edge of sensor ear,
rocking the sensor side to side until free.
INSTALLATION
(1) Connect the wheel speed sensor connector to
the wiring harness. (2) Push sensor assembly grommet into hole in
fender shield. Install clip and screw. (3) Install the 2 screws that fasten the speed sen-
sor routing tube to the frame rail. (4) Install sensor grommets in brackets on fender
shield and strut damper. (5) Coat the speed sensor with High Temperature
Multi-purpose E.P. Grease before installing into the
steering knuckle. Install screw tighten to 7 N Im (60
in. lbs.)
CAUTION: Proper installation of wheel speed sen-
sor cables is critical to continued system operation.
Be sure that cables are installed in retainers. Fail-
ure to install cables in retainers, as shown in this
section, may result in contact with moving parts
and/or over extension of cables, resulting in an
open circuit.
REAR WHEEL SPEED SENSOR (FIGS. 10 AND 11)
REMOVAL
(1) Raise vehicle and remove wheel and tire as-
sembly. (2) Remove sensor assembly grommet from under-
body and pull harness through hole in underbody. (3) Unplug connector from harness.
(4) Remove sensor assembly grommets from
bracket which is screwed into the body hose bracket,
just forward of trailing arm bushing (batwing brack-
et.) (5) Remove sensor and brake tube assembly clip,
located on the inboard side of trailing arm. (6) Remove sensor wire fastener from rear brake
hose bracket. (7) Remove outboard sensor assembly retainer nut.
This nut also is used to capture the brake tube clip. (8) Remove sensor head screw.
(9) Carefully, remove sensor head from adapter as-
sembly. If the sensor has seized, due to corrosion, DO
NOT USE PLIERS ON SENSOR HEAD. Use a ham-
mer and a punch and tap edge of sensor ear, rocking
the sensor side to side until free.
INSTALLATION Installation is reverse order of removal. Be sure to
coat sensor with High Temperature Multi-purpose
E.P. Grease before installing into adapter assembly.
Tighten screw to 7 N Im (60 in. lbs.) torque.
Fig. 9 Front Wheel Speed Sensor Routing
5 - 44 ANTILOCK 4 BRAKE SYSTEM Ä

Fig. 11 Body Routing of Rear Speed Sensor Wiring
Fig. 10 Rear Wheel Speed Sensor Routing at Trailing Arm
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 45

-37ÉC (-35ÉF) to -59ÉC (-50ÉF). If it looses color or
becomes contaminated, drain, flush, and replace with
fresh properly mixed solution.
SERVICE
Coolant should be changed at 52,500 miles or three
years, whichever occurs first, then every two years or
30,000 miles.
ROUTINE LEVEL CHECK
Do not remove radiator cap for routine coolant
level inspections. The coolant reserve system provides a quick visual
method for determining the coolant level without re-
moving the radiator cap. Simply observe, with the
engine idling and warmed up to normal operating
temperature, that the level of the coolant in the reserve
tank (Figs. 5 and 6) is between the minimum and
maximum marks.
ADDING ADDITIONAL COOLANT
The radiator cap should not be removed. When
additional coolant is needed to maintain this level, it
should be added to the coolant reserve tank. Use only
50/50 concentration of ethylene glycol type antifreeze
and water.
SERVICE COOLANT LEVEL
The cooling system is closed and designed to main-
tain coolant level to the top of the radiator. When servicing requires a coolant level check in the
radiator, the engine must be offand notunder pres-
sure. Drain several ounces of coolant from the radiator
drain cock while observing the Coolant Recovery Sys-
tem (CRS) Tank. Coolant level in the CRS tank should
drop slightly. Then remove the radiator cap. The radia-
tor should be full to the top. If not, and the coolant level
in the CRS tank is at the MIN mark there is a air leak
in the CRS system. Check hose or hose connections to
the CRS tank, radiator filler neck or the pressure cap
seal to the radiator filler neck for leaks.
LOW COOLANT LEVEL AERATION
Low coolant level in a cross flow radiator will equal-
ize in both tanks with engine off. With engine at
running operating temperature the high pressure inlet
tank runs full and the low pressure outlet tank drops.
If this level drops below the top of the transmission oil
cooler, air will be sucked into the water pump:
² Transmission oil will become hotter.
² High reading shown on the temperature gauge.
² Air in the coolant will also cause loss of flow through
the heater.
² Exhaust gas leaks into the coolant can also cause the
same problems.
DEAERATION
Air can only be removed from the system by gather-
ing under the pressure cap. On the next heat up it will
be pushed past the pressure cap into the CRS tank by
thermal expansion of the coolant. It then escapes to the
atmosphere in the CRS tank and is replaced with solid
coolant on cool down.
COOLING SYSTEM DRAIN, CLEAN, FLUSH AND
REFILL
Drain, flush, and fill the cooling system at the
mileage or time intervals specified in the Maintenance
Schedule in this Group. If the solution is dirty or rusty
or contains a considerable amount of sediment, clean
and flush with a reliable cooling system cleaner. Care
should be taken in disposing of the used engine coolant
from your vehicle. Check governmental regulations for
disposal of used engine coolant.
DRAINING
To drain cooling system move temperature selector
for heater to full heat with engine running (to provide
vacuum for actuation). Without removing radiator
pressure cap and with system not under pres-
sure, Shut engine off and open draincock. The coolant
reserve tank (Fig. 5) should empty first, then remove
radiator pressure cap. (if not, see Testing Cooling
System for leaks). To vent 2.2/2.5L engines remove the
plug above thermostat housing (Fig. 1). For Turbo III
engines remove coolant temperature sensor in the
thermostat housing (Fig. 2). For 3.3L /3.8L engine
remove the engine temperature sending unit (Fig. 3).
Removal of a plug or other component is required
because the thermostat has no air vent and prevents
air flow through it. This allows the coolant to drain
from the engine block.
Fig. 1 Thermostat Housing Drain/Fill PlugÐ2.2/2.5L Engines
Ä COOLING SYSTEM 7 - 15

CLEANING
Drain cooling system (see: Draining Cooling Sys-
tem ) and refill with clean water (see: Refilling
Cooling System ). Run engine with radiator cap in-
stalled until upper radiator hose is hot. Stop engine
and drain water from system. If water is dirty, fill,
run and drain system again until water runs clear.
REVERSE FLUSHING
Reverse flushing of the cooling system is the forc-
ing of water through the cooling system, using air
pressure in a direction opposite to that of the normal
flow of water. This is only necessary with dirty sys-
tems and evidence of partial plugging.
RADIATOR Drain cooling system and remove radiator hoses
from engine. Install suitable flushing gun in radiator
lower hose. Fill radiator with clean water and turn
on air in short blasts. CAUTION: Internal radiator pressure must not ex-
ceed 138 kPa (20 psi) as damage to radiator may re-
sult. Continue this procedure until water runs clear.
ENGINE
Drain radiator (see: Draining Cooling System )
and remove hoses from radiator. Remove engine
thermostat and reinstall thermostat housing. Install
suitable flushing gun to thermostat housing hose.
Turn on water, and when engine is filled, turn on
air, but no higher than 138 kPa (20 psi) in short
blasts. Allow engine to fill between blasts of air.
Continue this procedure until water runs clean. In-
stall thermostat using a new housing gasket. Fill
cooling system (See Refilling Cooling System ).
CHEMICAL CLEANING
One type of corrosion encountered with aluminum
cylinder heads is aluminum hydroxide deposits. Cor-
rosion products are carried to the radiator and depos-
ited when cooled off. They appear as dark grey when
wet and white when dry. This corrosion can be re-
moved with a two part cleaner (oxalic acid and neu-
tralizer) available in auto parts outlets. Follow
manufacturers directions for use.
REFILLING
First clean system to remove old glycol, see Cooling
System Cleaning. Fill system using antifreeze described in Coolant
section. Fill 50 percent of capacity with 100 percent
glycol. Then complete filling system with water. The
2.2/2.5L engines require venting by removal of the
plug on top of the water box (Fig. 1). Turbo III en-
gines require venting by removing the coolant tem-
perature sensor on top of the thermostat housing
(Fig. 2). The 3.3/3.8L Engines require removal of the
Engine Temperature Sending Unit on the front of
the cylinder head (Fig. 3). The thermostat in these
engines do not allow air flow through them. When
coolant reaches the vent holes;
² Install vent plug and tighten to 20 N Im (15 ft. lbs.)
for 2.2/2.5L Engines.
² Install Coolant Temperature Sensor and tighten to
27 N Im (20 ft. lbs.) for Turbo III Engine.
² Install Engine Temperature Sending Unit and
tighten to 7 N Im (60 in. lbs.) for 3.3/3.8L Engines.
Continue filling system until full, this provides bet-
ter heater performance. Be careful not to spill
coolant on drive belts or the generator. Fill coolant reserve system to at least the MAX
mark with 50/50 solution. It may be necessary to add
coolant to the reserve tank to maintain coolant level
between the MAX and MIN mark after three or four
warm-up, cool down cycles and trapped air has been
removed.
Fig. 2 Coolant Temperature SensorÐTurbo III Drain/Fill
Fig. 3 Engine Temperature Sending UnitÐ3.3L and 3.8L Drain/Fill
7 - 16 COOLING SYSTEM Ä

TESTING SYSTEM FOR LEAKS
With engine not running, wipe the radiator filler
neck sealing seat clean. The radiator should be full. Attach a radiator pressure tester to the radiator, as
shown in (Fig. 4) and apply 104 kPa (15 psi) pres-
sure. If the pressure drops more than 2 psi in 2 min-
utes inspect all points for external leaks. All hoses, radiator and heater, should be moved
while at 15 psi since some leaks occur while driving
due to engine rock, etc.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start en-
gine and run the engine to normal operating temper-
ature in order to open the thermostat and allow the
coolant to expand. Re-attach the tester. If the needle
on the dial fluctuates it indicates a combustion leak,
usually a head gasket leak.
WARNING: WITH TOOL IN PLACE PRESSURE
BUILDS UP FAST. ANY EXCESSIVE AMOUNT OF
PRESSURE BUILT UP BY CONTINUOUS ENGINE
OPERATION MUST BE RELEASED TO A SAFE
PRESSURE POINT. NEVER PERMIT PRESSURE TO
EXCEED 138 KPA (20 PSI).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam is emitted from the tail pipe, it may
indicate a faulty head gasket, cracked engine block
or cylinder head. There may be internal leaks which can be deter-
mined by removing the oil dip-stick. If water glob-
ules appear intermixed with the oil it will indicate a internal leak in the engine. If there is an internal
leak, the engine must be disassembled for repair.
COOLANT RECOVERY SYSTEM (CRS)
This system works in conjunction with the radiator
pressure cap to utilize thermal expansion and con-
traction of the coolant to keep the coolant free of
trapped air. It provides a volume for expansion and
contraction, provides a convenient and safe method
for checking coolant level and adjusting level at at-
mospheric pressure without removing the radiator
pressure cap. It also provides some reserve coolant to
cover minor leaks and evaporation or boiling losses.
All vehicles are equipped with this system (Figs. 5
and 6).
See Coolant Level Check Service, Deaeration and
Pressure Cap sections for operation and service. Ve-
hicles equipped with the electric monitor system use
a level sensor in the CRS tank, see Group 8E Elec-
trical for service.
Fig. 4 Pressure Testing Cooling System
Fig. 5 Coolant Recovery System Typical
Fig. 6 Coolant Recovery SystemÐAC-AY Models
Ä COOLING SYSTEM 7 - 17

RADIATOR HOSES
The hoses are removed using Constant Tension
Clamp pliers to compress hose clamp. A hardened, cracked, swollen or restricted hose
should be replaced. Do not damage radiator inlet and
outlet when loosening hoses. Radiator hoses should be routed without any kinks
and indexed as designed. The use of molded hoses is
recommended. Spring type hose clamps are used in all applica-
tions. If replacement is necessary replace with the
original style spring type clamp.
FANS
All models use electric motor driven cooling system
fans. The fan modules include a motor support which
may (depending on model) include a shroud. The
module is fastened to the radiator by screws with
U-nuts and retaining clips (Fig. 12). All fan motors are one speed. Attempts to reduce
high temperature gauge reading by increasing en-
gine speed, at the same vehicle speed, can increase
high temperature.
SINGLE FAN
There are no repairs to be made to the fan. If the
fan is warped, cracked, or otherwise damaged, it must be replaced with
onlythe recommended part for
adequate strength, performance and safety (Fig. 13).
DUAL FAN MODULEÐAC/AY BODY
The dual fan module (Fig. 11) is a combination of 2
fans mounted in a one piece shroud which are simul-
taneously activated. The dual fan system improves
engine cooling and air conditioning performance in hot
weather and severe driving conditions, while reducing
fan noise and power consumption.
REMOVAL
Disconnect electric motor lead. Remove fan module
to radiator fasteners and retaining clips. Remove as-
sembly from radiator support. To remove fan from motor shaft, bench support the
motor and motor shaft, while removing the fan retain-
ing clip, so that the shaft and motor will not be
damaged by excessive force. Surface or burr re-
moval may be required to remove fan from motor
shaft. (Fig. 13). Do not permit the fan blades to touch
the bench.
INSTALLATION
Slide the fan on motor shaft. Support motor and
shaft as above while installing fan retaining clip.
Install assembly into pocket on lower radiator tank.
Attach retaining clips and fasteners to radiator tank.
Right side fastener is longer on A/C equipped
vehicles . Connect fan motor lead. For wiring dia-
grams of fan motor systems see Wiring Diagrams
Manual
RADIATOR FAN CONTROLÐALL EXCEPT V-6 ENGINE
Fan control is accomplished two ways. The fan al-
ways runs when the air conditioning compressor
clutch is engaged. In addition to this control, the fan is
turned on by the temperature of the coolant which is
sensed by the coolant temperature sensor which
Fig. 12 Servicing Fan Module
Fig. 13 Radiator Fan Retaining ClipÐTypical
Ä COOLING SYSTEM 7 - 21

After 15 seconds, record the loaded voltage reading
and return the load control to the off position. (6) Voltage drop will vary according to battery
temperature at the time of the load test. Battery
temperature can be estimated by the temperature of
exposure over the preceding several hours. If the bat-
tery has been charged, boosted, or loaded a few min-
utes prior to the test, the battery would be slightly
warmer. Refer to Fig. 14 for proper loaded voltage
reading.
(7) If battery passes load test, it is in good condi-
tion and further tests are not necessary. If it fails
load test, it should be replaced.
BATTERY CHARGING
A battery is considered fully charged when it will
meet all the following requirements:
² It has an open circuit voltage charge of at least
12.4 volts (Fig. 9)
² It passes the 15 second load test (Fig. 14)
² The built in test indicator dot is GREEN (Fig. 5)
² The battery cannot be refilled with water. It must
be replaced WARNING: DO NOT CHARGE A BATTERY THAT
HAS EXCESSIVELY LOW ELECTROLYTE LEVEL.
BATTERY MAY SPARK INTERNALLY AND EX-
PLODE. EXPLOSIVE GASES FORM OVER THE BATTERY.
DO NOT SMOKE, USE FLAME, OR CREATE
SPARKS NEAR BATTERY. DO NOT ASSIST BOOST OR CHARGE A FROZEN
BATTERY. BATTERY CASING MAY FRACTURE. BATTERY ACID IS POISON, AND MAY CAUSE SE-
VERE BURNS AND THE BATTERY CONTAIN SUL-
FURIC ACID. AVOID CONTACT WITH SKIN, EYES,
OR CLOTHING. IN THE EVENT OF CONTACT,
FLUSH WITH WATER AND CALL PHYSICIAN IMME-
DIATELY. KEEP OUT OF REACH OF CHILDREN.
CAUTION: Disconnect the battery negative cable
first (Fig. 15) before charging battery to avoid dam-
age to electrical systems. Do not exceed 16.0 volts
while charging battery. Refer to the instructions
supplied with charging equipment
Battery electrolyte will bubble inside the battery
case while being charged properly. If the electrolyte
boils violently, or is discharged from the vent holes
while charging, immediately reduce charging rate or
turn off charger. Evaluate battery condition. Battery
damage may occur if charging is excessive. Some battery chargers are equipped with polarity
sensing devices to protect the charger or battery from
being damaged if improperly connected. If the bat-
tery state of charge is too low for the polarity sensor
to detect, the sensor must be bypassed for charger to
operate. Refer to operating instructions provided
with battery charger being used.
CAUTION: Charge battery until test indicator ap-
pears green. Do not overcharge.
It may be necessary to jiggle the battery or vehicle
to bring the green dot (in the test indicator) into
view. After the battery has been charged to 12.4 volts or
greater, perform a load test to decide cranking capac-
Fig. 13 Load 50 Percent Cold Crank Rating
Fig. 14 Load Test Temperature
Fig. 15 Disconnect Negative Battery Cable
Ä BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 7