Jeep Cherokee 2000 Service Manual - page 1948
Exhaust System: The ECM cannot detect a
plugged, restricted or leaking exhaust system.
Fuel Injector Malfunctions: The ECM cannot
determine if the fuel injector is clogged, or the wrong
injector is installed. The fuel injectors on the diesel
engine are not controlled by the ECM, although a
defective needle movement sensor in the #1 injector
is monitored by the ECM.
Vacuum Assist: Leaks or restrictions in the vac-
uum circuits of the Exhaust Gas Recirculation Sys-
tem (EGR) are not monitored by the ECM.
ECM System Ground: The ECM cannot deter-
mine a poor system ground. However, a DTC may be
generated as a result of this condition.
ECM/PCM Connector Engagement: The ECM
cannot determine spread or damaged connector pins.
However, a DTC may be generated as a result of this
condition.
HIGH AND LOW LIMITS
The ECM compares input signals from each input
device. It has high and low limits that are pro-
grammed into it for that device. If the inputs are not
within specifications and other DTC criteria are met,
a DTC will be stored in memory. Other DTC criteria
might include engine rpm limits or input voltages
from other sensors or switches. The other inputs
might have to be sensed by the ECM when it senses
a high or low input voltage from the control system
device in question.
DIAGNOSTIC TROUBLE CODES
DESCRIPTION
On the following pages, a list of DTC’s is provided
for the 2.5L diesel engine. A DTC indicates that the
ECM has recognized an abnormal signal in a circuit
or the system. A DTC may indicate the result of a
failure, but most likely will not identify the failed
component directly.
ACCESSING DIAGNOSTIC TROUBLE CODES
A stored DTC can be displayed through the use of
the DRB III
t
scan tool. The DRB III
t
connects to the
data link connector. The data link connector is
located under the instrument panel near bottom of
the steering column (Fig. 1) (Fig. 2).
ERASING TROUBLE CODES
After the problem has been repaired, use the DRB
III
t
scan tool to erase a DTC.
Fig. 1 Data Link Connector Location—LHD
1 – 16–WAY DATA LINK CONNECTOR
Fig. 2 Data Link Connector Location—RHD
1 – DATA LINK CONNECTOR
25 - 2
EMISSION CONTROL SYSTEM
XJ
DESCRIPTION AND OPERATION (Continued)