Jeep Cherokee 2000 Service Manual - page 1255
informs the ECM that a fixed vehicle speed has been
selected. The Resume input indicates to the ECM that
the previous fixed speed is requested.
Speed control operation will start at 50 km/h–142
km/h (35–85 mph). The upper range of operation is
not restricted by vehicle speed. Inputs that effect
speed control operation are vehicle speed sensor and
accelerator pedal position sensor.
Refer to Group 8H for further speed control infor-
mation.
ASD RELAY—ECM INPUT
DESCRIPTION
A 12 volt signal at this input indicates to the ECM
that the ASD relay has been activated. The ASD
relay is located in the PDC. The PDC is located next
to the battery in the engine compartment. For the
location of the relay within the PDC, refer to label on
PDC cover.
This input is used only to sense that the ASD relay
is energized. If the ECM does not see 12 volts (+) at
this input when the ASD relay should be activated, it
will set a Diagnostic Trouble Code (DTC).
FIVE VOLT POWER—ECM/PCM OUTPUT
DESCRIPTION
This circuit supplies approximately 5 volts to
power the Accelerator Pedal Position Sensor, and the
Boost Pressure Sensor.
ENGINE COOLANT GAUGE—PCM OUTPUT
DESCRIPTION
Refer to the Instrument Panel and Gauges group
for additional information.
ENGINE OIL PRESSURE GAUGE—PCM
OUTPUT
DESCRIPTION
Refer to the Instrument Panel and Gauges group
for additional information.
GLOW PLUG LAMP—PCM OUTPUT
DESCRIPTION
The Glow Plug lamp (malfunction indicator lamp)
illuminates on the message center each time the igni-
tion (key) switch is turned on. It will stay on for
about two seconds as a bulb test.
SPEED CONTROL—PCM OUTPUTS
DESCRIPTION
These two circuits control the fuel quantity actua-
tor to regulate vehicle speed. Refer to Group 8H for
Speed Control information.
AIR CONDITIONING RELAY—ECM OUTPUT
DESCRIPTION
This circuit controls a ground signal for operation
of the A/C clutch relay. Also refer to Air Conditioning
(A/C) Controls—ECM Input for additional informa-
tion.
The A/C relay is located in the Power Distribution
Center (PDC). The PDC is located next to the battery
in the engine compartment. For the location of the
relay within the PDC, refer to label on PDC cover.
TIMING SOLENOID—ECM OUTPUT
DESCRIPTION
The timing solenoid is located on the bottom of the
fuel injection pump (Fig. 12).
This 12(+) volt, pulse width modulated (duty–cycle)
output controls the amount of fuel timing (advance)
in the fuel injection pump. The higher the duty–cy-
cle, the lower the advance. The lower the duty–cycle,
the more advanced the fuel timing.
Fig. 11 Glow Plug Lamp Symbol
Fig. 12 Timing Solenoid
1 – FUEL INJECTION PUMP ASSEMBLY
2 – FUEL RETURN LINE
3 – FUEL SUPPLY LINE
4 – FUEL INJECTION PUMP 10–WAY CONNECTOR
5 – TIMING SOLENOID
6 – OVERFLOW VALVE
XJ
FUEL SYSTEM—2.5L DIESEL ENGINE
14 - 29
DESCRIPTION AND OPERATION (Continued)