Jeep Cherokee 2000 Service Manual - page 1254
BRAKE SWITCH—ECM INPUT
DESCRIPTION
When the brake light switch is activated, the ECM
receives an input indicating that the brakes are
being applied. After receiving this input, the ECM is
used to control the speed control system. There is a
Primary and a Secondary brake switch. The Second-
ary brake switch is closed until the brake pedal is
pressed.
DATA LINK CONNECTOR—PCM AND ECM
INPUT AND OUTPUT
The 16–way data link connector (diagnostic scan
tool connector) links the Diagnostic Readout Box
(DRB) scan tool with the PCM and ECM. The data
link connector is located under the instrument panel
near the left body side cowl panel on left hand drive
vehicles (Fig. 8). And near the right body side cowl
panel on right hand drive vehicles (Fig. 9).
VEHICLE SPEED SENSOR—ECM INPUT
The vehicle speed sensor is located in the transfer
case extension housing (Fig. 10). The sensor input is
used by the ECM to determine vehicle speed and dis-
tance traveled.
The speed sensor generates 8 pulses per sensor
revolution. These signals, in conjunction with a
closed throttle signal from the accelerator pedal posi-
tion sensor, indicate an idle deceleration to the ECM.
When the vehicle is stopped at idle, a released pedal
signal is received by the ECM (but a speed sensor
signal is not received).
In addition to determining distance and vehicle
speed, the output from the sensor is used to control
speed control operation.
SPEED CONTROL—ECM INPUT
DESCRIPTION
The speed control system provides five separate
inputs to the ECM: On/Off, Set, Resume/Accel, Cancel,
and Decel.. The On/Off input informs the ECM that the
speed control system has been activated. The Set input
Fig. 8 Data Link Connector Location – LHD
1 – 16–WAY DATA LINK CONNECTOR
Fig. 9 Data Link Connector Location –RHD
1 – DATA LINK CONNECTOR
Fig. 10 Vehicle Speed Sensor—4 Wheel Drive
1 – 4WD TRANSFER CASE EXTENSION
2 – VEHICLE SPEED SENSOR
3 – SENSOR ELECTRICAL CONNECTOR
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FUEL SYSTEM—2.5L DIESEL ENGINE
XJ
DESCRIPTION AND OPERATION (Continued)