Jeep 1996 Grand Cherokee Service Manual - page 543
• Upstream and downstream heated oxygen sen-
sors
• Camshaft position sensor
• Crankshaft position sensor
• Intake air temperature sensor
• Manifold absolute pressure sensor
• Engine coolant temperature sensor
• Vehicle speed sensor
MANIFOLD ABSOLUTE PRESSURE SENSOR
From the Powertrain Control Module (PCM), cir-
cuit K25 supplies 5 volts to the manifold absolute
pressure (MAP) sensor. Circuit K25 connects to cav-
ity A17 of the PCM.
Circuit K70 delivers the MAP signal to the PCM.
Circuit K70 connects to cavity A27 of the PCM.
The PCM provides a ground for the MAP sensor
signal (circuit K70) through circuit K4. Circuit K4
connects to cavity A4 of the PCM.
HELPFUL INFORMATION
Refer to Group 14 for MAP sensor operation.
Circuit K25 splices to supply 5 volts to the cam-
shaft position sensor, crankshaft position sensor and
throttle position sensor.
Circuit K4 splices to supply ground for the signals
from the following:
• Upstream and downstream heated oxygen sen-
sors
• Camshaft position sensor
• Crankshaft position sensor
• Intake air temperature sensor
• Throttle position sensor
• Engine coolant temperature sensor
• Vehicle speed sensor
INTAKE AIR TEMPERATURE SENSOR
The intake air temperature sensor provides an
input to the Powertrain Control Module (PCM) on
circuit K21. Circuit K21 connects to cavity A15 of the
PCM.
From circuit K21, the intake air temperature sen-
sor draws voltage from the PCM. The sensor is a
variable resistor. As intake air temperature changes,
the resistance in the sensor changes, causing a
change in current draw.
The PCM provides a ground for the intake air tem-
perature sensor signal (circuit K21) through circuit
K4. Circuit K4 connects to cavity A4 of the PCM.
HELPFUL INFORMATION
Circuit K4 splices to supply ground for the signals
from the following:
• Upstream and downstream heated oxygen sen-
sors
• Camshaft position sensor
• Crankshaft position sensor
• Throttle position sensor
• Manifold absolute pressure sensor
• Engine coolant temperature sensor
• Vehicle speed sensor
OIL PRESSURE SENSOR
The oil pressure sensor is a variable resistor. A
change in engine oil pressure changes the resistance
in the sending unit which alters the signal sensed by
the Powertrain Control Module on circuit G6. Circuit
G6 connects to cavity B23 of the PCM.
The PCM provides ground for the oil pressure sen-
sor on circuit K4. Circuit K4 connects to cavity A4 of
the PCM.
The PCM broadcasts the oil pressure data on the
CCD bus. The micro-processor in the instrument
cluster receives the signal from the CCD bus, calcu-
lates oil pressure and adjusts the gauge needle posi-
tion.
The Body Control Module (BCM) also receives the
oil pressure data broadcast by the PCM on the CCD
bus. If oil pressure drops below a calibrated pressure,
the BCM sounds an audible chime and illuminates
the oil pressure warning lamp.
FUEL INJECTORS
When the Automatic Shut Down (ASD) relay con-
tacts close, they connect circuit A142 supplies voltage
to the fuel injectors. Each injector has a separate
ground circuit controlled by the Powertrain Control
Module (PCM).
Circuit K11 provides ground for injector number
one. The K11 circuit connects to cavity B4 of the
PCM.
Circuit K12 provides ground for injector number
two. The K12 circuit connects to cavity B15 of the
PCM.
Circuit K13 provides ground for injector number
three. The K13 circuit connects to cavity B5 of the
PCM.
Circuit K14 provides ground for injector number
four. The K14 circuit connects to cavity B16 of the
PCM.
Circuit K38 provides ground for injector number
five. The K38 circuit connects to cavity B6 of the
PCM.
Circuit K58 provides ground for injector number
six. The K58 circuit connects to cavity B12 of the
PCM.
On the 5.2L engine, circuit K17 provides ground
for injector number seven. The K17 circuit connects
to cavity B2 of the PCM.
Also on the 5.2L engine, circuit K18 provides
ground for injector number eight. The K18 circuit
connects to cavity B13 of the PCM.
8W - 30 - 4
8W - 30 FUEL/IGNITION SYSTEMS
ZJ
DESCRIPTION AND OPERATION (Continued)