Locate water temp sensoe,82 GMC s15 - 1983 GMC S-15 Pickup

Sending Units and Sensors
REMOVAL & INSTALLATION
Engine Coolant Temperature
On all vehicles covered by this manual an Engine Coolant Temperature (ECT)
sensor can be found threaded into one of the engine coolant passages. The sensor
is a thermistor (a resistor which changes value based on temperature) and is
used on all computer controlled fuel systems to help regulate fuel and emissions
systems controlled by the computer module. The sensor may be found in various
places on the engine. Most engines will likely have this sensor threaded into
the intake manifold, often near the thermostat housing.





Fig. 1: On most vehicles such as the 4.3L (VIN Z) engine, the
coolant temperature sensor is mounted in the intake manifold


NOTE: Care must be taken when handling engine control related
sensors as damage to the sensor may adversely affect engine driveability and
emissions.

1. Disconnect the negative battery cable.
   
2. Drain the engine cooling system to a level below the sensor.
   
3. Release the locktab and disengage the sensor connector.
   
4. Using a special sensor tool or a deep 12-point socket, loosen the sensor,
   then carefully unthread and remove it from the engine.
   To install:
   
   
5. Thread the sensor into the engine by hand, then tighten using the socket or
   tool. If a replacement sensor came with instructions use a torque wrench to
   assure proper tightening.
   NOTE: On some engines, such as the Syclone's MFI 4.3L engine,
   the manufacturer suggests coating the coolant sensor threads with a sealant such
   as 1052080, or equivalent.
   
   
   
6. Engage the sensor wiring harness.
   
7. Connect the negative battery cable.
   
8. Properly refill the engine cooling system, then run the engine and check for
   leaks.
   
   
   
   
   
   Fig. 2: Coolant temperature sensor location - 4.3L (VIN W)
   engine
   
   

Manifold Absolute Pressure (MAP) Sensor
The MAP sensor measures changes in the intake manifold pressure, resulting
from changes in engine load and speed changes, then converts this to a voltage
output. Other than checking for loose vacuum hoses or electrical connectors, the
only service possible for this sensor is replacement, if testing shows the
sensor is faulty.

1. Disconnect the negative battery cable.
   
2. Release the locktab, then disengage the sensor electrical connector.
   
3. Either tag and disconnect the hoses from the MAP sensor or disengage the
   entire vacuum harness assembly from the sensor, as applicable.
   
4. Either remove the retainers or release the lock tabs, then remove the sensor
   from the engine.
   To install:
   
   
5. Install the sensor and secure in position using the retainers or lock tabs,
   as applicable.
   
6. Connect the vacuum harness or hoses to the sensor as noted during removal.
   
7. Engage the sensor electrical connector.
   
8. Connect the negative battery cable.
   
   
   
   
   
   Fig. 3: Common MAP sensor mounting (4.3L VIN Z engine shown)
   
   
   
   
   
   
   
   Fig. 4: MAP sensor (and other upper intake mounted component)
   installation - 4locate water temp sensoe,82 GMC s15 - 85383041.gifengine
   
   

Oxygen Sensor
Almost all vehicles covered by this manual were equipped with an oxygen
sensor for feedback carburetor control . Fuel injected engines, introduced to
the S/T series in 1985 and used on all of these trucks built in 1986 and later
also require an oxygen sensor for computer air/fuel mixture management. On
vehicles so equipped, the oxygen sensor is usually mounted in an exhaust
manifold. On some engines, the sensor is mounted at the end of the crossover
pipe.

1. Disconnect the negative battery cable.
   
2. Locate the oxygen sensor. The sensor is usually mounted in the exhaust
   manifold or in the crossover pipe. If necessary, raise and support the front of
   the truck safely using jackstands.
   
3. Trace the wires leading from the oxygen sensor back to the first connector
   and then disengage the sensor harness connector.
   NOTE: The sensor may be extremely difficult to remove when
   engine temperature is below 120°F (48°C). Be careful as excessive force could
   damage threads in the exhaust manifold or pipe.
   
   
   
4. Using a special sensor tool or a socket, loosen the sensor, then carefully
   unthread and remove it from the engine. If sensor removal is difficult, spray a
   small amount of commercial heat riser solvent onto the sensor threads and allow
   it to soak in for at least five minutes, then attempt to loosen and remove the
   sensor again.
   CAUTION
   Avoid using cleaning solvents of any type on
   the oxygen sensor. Keep the louvered end free of grease, dirt or other
   contaminants. Do not drop or roughly handle the sensor. If any of these cautions
   are ignored, the sensor could be damaged resulting in poor engine performance
   and excessive exhaust emissions.
   To install:
   
   
5. New oxygen sensors will be packaged with a special anti-seize lubricant
   already applied to the threads. If a sensor is removed from the exhaust and is
   to be reinstalled for any reason, the sensor threads must be coated with a fresh
   anti-seize compound. Use a G.M. anti-seize compound no. 5613695, no. 3613695 or
   an equivalent compound made of liquid graphite and glass beads. This is not a
   conventional anti-seize paste, the graphite will tend to burn away but the glass
   beads will remain. The use of a regular compound may electrically insulate the
   sensor, rendering it inoperative. You must coat the threads with an electrically
   conductive anti-seize compound.
   
6. Carefully thread the sensor into the exhaust bore, then tighten to 30 ft.
   lbs. (41 Nm) using a torque wrench.
   
7. Engage the sensor harness.
   
8. If raised, remove the jackstands and carefully lower the truck.
   
9. Connect the negative battery cable, then start and run the engine to check
   for proper operation.