2003 JEEP GRAND CHEROKEE Cruise

²The speed signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)
Once the speed control has been disengaged,
depressing the RES/ACCEL switch (when speed is
greater than 30 mph) restores the vehicle to the tar-
get speed that was stored in the PCM.
While the speed control is engaged, the driver can
increase the vehicle speed by depressing the RES/AC-
CEL switch. The new target speed is stored in the
PCM when the RES/ACCEL is released. The PCM
also has a9tap-up9feature in which vehicle speed
increases at a rate of approximately 2 mph for each
momentary switch activation of the RES/ACCEL
switch.
A ªtap downº feature is used to decelerate without
disengaging the speed control system. To decelerate
from an existing recorded target speed, momentarily
depress the COAST switch. For each switch activa-
tion, speed will be lowered approximately 1 mph.
OVERSHOOT/UNDERSHOOT
If the vehicle operator repeatedly presses and
releases the SET button with their foot off of the
accelerator (referred to as a ªlift foot setº), the vehicle
may accelerate and exceed the desired set speed by
up to 5 mph (8 km/h). It may also decelerate to less
than the desired set speed, before finally achieving
the desired set speed.
The Speed Control System has an adaptive strat-
egy that compensates for vehicle-to-vehicle variations
in speed control cable lengths. When the speed con-
trol is set with the vehicle operators foot off of the
accelerator pedal, the speed control thinks there is
excessive speed control cable slack and adapts
accordingly. If the ªlift foot setsº are continually used,
a speed control overshoot/undershoot condition will
develop.
To ªunlearnº the overshoot/undershoot condition,
the vehicle operator has to press and release the set
button while maintaining the desired set speed using
the accelerator pedal (not decelerating or accelerat-
ing), and then turning the cruise control switch to
the OFF position (or press the CANCEL button if
equipped) after waiting 10 seconds. This procedure
must be performed approximately 10±15 times to
completely unlearn the overshoot/undershoot condi-
tion.DIAGNOSIS AND TESTING - ROAD TEST
Perform a vehicle road test to verify reports of
speed control system malfunction. The road test
should include attention to the speedometer. Speed-
ometer operation should be smooth and without flut-
ter at all speeds.
Flutter in the speedometer indicates a problem
which might cause surging in the speed control sys-
tem. The cause of any speedometer problems should
be corrected before proceeding. Refer to Group 8J,
Instrument Cluster for speedometer diagnosis.
If a road test verifies a system problem and the
speedometer operates properly, check for:
²A Diagnostic Trouble Code (DTC). If a DTC
exists, conduct tests per the Powertrain Diagnostic
Procedures service manual.
²A misadjusted brake (stop) lamp switch. This
could also cause an intermittent problem.
²Loose, damaged or corroded electrical connec-
tions at the servo. Corrosion should be removed from
electrical terminals and a light coating of Mopar
MultiPurpose Grease, or equivalent, applied.
²Leaking vacuum reservoir.
²Loose or leaking vacuum hoses or connections.
²Defective one-way vacuum check valve.
²Secure attachment of both ends of the speed con-
trol servo cable.
²Smooth operation of throttle linkage and throttle
body air valve.
²Failed speed control servo. Do the servo vacuum
test.
CAUTION: When test probing for voltage or conti-
nuity at electrical connectors, care must be taken
not to damage connector, terminals or seals. If
these components are damaged, intermittent or
complete system failure may occur.
8P - 2 SPEED CONTROLWJ
SPEED CONTROL (Continued)

SPLICE
NUMBERLOCATION FIG.
S210 (RHD) Lower Center Instrument Panel 22
S211 In Trough Near T/O for Left Courtesy Lamp N/S
S211 (RHD) Right Side of Instrument Panel 22
S212 In Trough Near T/O for Left Courtesy Lamp 21
S212 (RHD) Right Center Instrument Panel 22
S213 Near T/O for Cruise Switch No.1 N/S
S214 Near T/O for Cruise Switch No.1 N/S
S215 Near T/O for Horn Switch N/S
S216 Near T/O for Remote Radio Switch No.2 N/S
S217 In Trough Near T/O for Power Connector 21
S217 (RHD) Lower Center Instrument Panel 22
S221 Right Center of Instrument Panel 21
S221 (RHD) Left Center of Instrument Panel 22
S222 Right Center of Instrument Panel 21
S222 (RHD) Near T/O for Front Power Outlet 22
S223 Near T/O for Adjustable Pedals Switch 21
S223 (RHD) Lower Left Side of Instrument Panel 22
S224 Right Center of Instrument Panel 21
S224 (RHD) Upper Center of Instrument Panel 22
S300 Near T/O for G304 33
S301 In T/O for C304 33
S302 In Sill Trough Near T/O for C307 33, 35
S303 In Sill Trough Near T/O for C307 33, 35
S304 In Sill Trough Near T/O for C307 35
S305 In Sill Trough Near T/O for C307 N/S
S306 Near T/O for C310 37
S307 Near T/O for C310 37
S308 Between T/O's for C310 and Left Rear Lamp Assembly 36, 37
S309 Between T/O's for C310 and Left Rear Lamp Assembly 37
S310 Between T/O's for C310 and Left Rear Lamp Assembly 35, 37
S311 Near T/O for Left Rear Lamp Assembly 37
S312 Near T/O for C200 35
S313 Near T/O for G301 35
S314 Near T/O for C314 N/S
S315 (Gas) In Center Spline Near T/O for G301 35
S316 (Gas) Near T/O for Junction Block C2, C4, C5 N/S
S317 Between Troughs Near T/O for C314 N/S
S318 Between Troughs Near T/O for C314 N/S
S319 In Trough Near T/O for C304 33
S323 Near T/O for C314 N/S
S324 In T/O for C200 34
WJ8W-91 CONNECTOR/GROUND/SPLICE LOCATION 8W - 91 - 15
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0545 A/C Clutch Relay Circuit Problem detected in air conditioning clutch relay control
circuit.
P0551 Power Steering Switch Failure Incorrect input state detected for the power steering
switch circuit. PL: High pressure seen at high speed.
P0562 Charging System Voltage Too Low Supply voltage sensed at ECM too low.
P0563 Charging System Voltage Too High Supply voltage sensed at ECM too high.
P0572 Brake Switch Input #1 Signal
Missing
P0573 Brake Switch Input #2 Signal
Missing
P0575 Cruise Control Switch Voltage Low
P0576 Cruise Control Switch Voltage High
P0577 Cruise Control Switch Voltage High
P0600 PCM Failure SPI Communications No communication detected between co-processors in the
control module.
P0601 (M) Internal Controller Failure Internal control module fault condition (check sum)
detected.
P0602 (M) ECM Fueling Calibration Error ECM Internal fault condition detected.
P0604 RAM Check Failure Transmission control module RAM self test fault detected.
-Aisin transmission
P0605 ROM Check Falure Transmission control module ROM self test fault detected
-Aisin transmission
P0606 (M) ECM Failure ECM Internal fault condition detected.
P0615 Starter Relay Control Circuit An open or shorted condition detected in the starter relay
control circuit.
P0622 (G) Generator Field Not Switching
ProperlyAn open or shorted condition detected in the generator
field control circuit.
P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch
relay control circuit.
P0700 EATX Controller DTC Present This SBEC III or JTEC DTC indicates that the EATX or
Aisin controller has an active fault and has illuminated the
MIL via a CCD (EATX) or SCI (Aisin) message. The
specific fault must be acquired from the EATX via CCD or
from the Aisin via ISO-9141.
P0703 Brake Switch Stuck Pressed or
ReleasedIncorrect input state detected in the brake switch circuit.
(Changed from P1595)
P0703 Brake Switch Sense Circuit
P0711 (M) Trans Temp Sensor, No Temp Rise
After StartRelationship between the transmission temperature and
overdrive operation and/or TCC operation indicates a
failure of the Transmission Temperature Sensor. OBD II
Rationality. Was MIL code 37.
P0712 Trans Temp Sensor Voltage Too Low Transmission fluid temperature sensor input below
acceptable voltage. Was MIL code 37.
WJEMISSIONS CONTROL 25 - 9
EMISSIONS CONTROL (Continued)