Jeep Cherokee 1999 Electronic Service Manual page 1266

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FU EL I N J ECT I ON SY ST EM —2 .5 L DI ESEL EN GI N E
GENERAL INFORMATION
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 23
DESCRIPTION AND OPERATION
AIR CONDITIONING (A/C) CONTROLS—
ECM INPUTS . . . . . . . . . . . . . . . . . . . . . . . . . 27
AIR CONDITIONING RELAY—ECM OUTPUT . . . 28
ASD RELAY—ECM INPUT . . . . . . . . . . . . . . . . . 28
BATTERY VOLTAGE—PCM INPUT . . . . . . . . . . . 25
BOOST / PRESSURE SENSOR . . . . . . . . . . . . . 25
BRAKE SWITCH—ECM INPUT . . . . . . . . . . . . . . 27
DATA LINK CONNECTOR—PCM AND ECM
INPUT AND OUTPUT . . . . . . . . . . . . . . . . . . . 27
ELECTRIC VACUUM MODULATOR (EVM)—
ECM OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . 30
ENGINE COOLANT GAUGE—PCM OUTPUT . . . 28
ENGINE COOLANT TEMPERATURE SENSOR—
ECM/PCM INPUT . . . . . . . . . . . . . . . . . . . . . . 26
ENGINE OIL PRESSURE GAUGE—
PCM OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . 28
ENGINE SPEED/CRANK POSITION SENSOR—
ECM INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
FIVE VOLT POWER—ECM/PCM OUTPUT . . . . . 28
FUEL INJECTOR SENSOR—GROUND . . . . . . . . 26
GLOW PLUG LAMP—PCM OUTPUT . . . . . . . . . 28
GLOW PLUG RELAY—ECM OUTPUT . . . . . . . . 29
GLOW PLUGS . . . . . . . . . . . . . . . . . . . . . . . . . . 30
IGNITION CIRCUIT SENSE—MSA/PCM INPUT . 25
IGNITION CIRCUIT SENSE—PCM INPUT . . . . . 26
NEEDLE MOVEMENT OR INSTRUMENTED
FIRST INJECTOR—ECM INPUT . . . . . . . . . . . 26
POWER GROUND . . . . . . . . . . . . . . . . . . . . . . . 26
POWERTRAIN CONTROL MODULE (PCM) . . . . 24
GEN ERAL I N FORM AT I ON
INTRODUCTION
Th is sect ion will cover com pon en t s eit h er r egu la t ed
or con t r olled by t h e E CM con t r oller a n d t h e P ower-
t r a in Con t r ol Modu le (P CM). Th e fu el h ea t er r ela y
a n d fu el h ea t er a r e n ot oper a t ed by t h e E CM con t r ol-
ler or t h e P CM. Th ese com pon en t s a r e con t r olled by
t h e ign it ion (key) swit ch . All ot h er fu el syst em elec-
t r ica l com pon en t s n ecessa r y t o oper a t e t h e en gin e
a r e con t r olled or r egu la t ed by t h e E CM con t r oller,
wh ich in t er fa ces wit h t h e P CM. Refer t o t h e follow-
in g descr ipt ion for m or e in for m a t ion .
Cer t a in fu el syst em com pon en t fa ilu r es m a y ca u se
a n o st a r t , or pr even t t h e en gin e fr om r u n n in g. It is
FUEL SYSTEM—2.5L DIESEL ENGINE
INDEX
page
SENSOR RETURN—ECM/PCM INPUT
(ANALOG GROUND) . . . . . . . . . . . . . . . . . . . . 25
SPEED CONTROL—ECM INPUT . . . . . . . . . . . . 28
SPEED CONTROL—PCM OUTPUTS . . . . . . . . . 28
TACHOMETER—PCM OUTPUT . . . . . . . . . . . . . 29
TIMING SOLENOID—ECM OUTPUT . . . . . . . . . . 29
VEHICLE SPEED SENSOR—ECM INPUT . . . . . 27
VEHICLE THEFT ALARM . . . . . . . . . . . . . . . . . . 25
DIAGNOSIS AND TESTING
ASD RELAY TEST . . . . . . . . . . . . . . . . . . . . . . . 30
BOOST / PRESSURE SENSOR . . . . . . . . . . . . . 33
DIAGNOSTIC TROUBLE CODES . . . . . . . . . . . . 34
DIESEL DIAGNOSTICS . . . . . . . . . . . . . . . . . . . 30
ENGINE COOLANT TEMPERATURE
SENSOR TEST . . . . . . . . . . . . . . . . . . . . . . . . 30
ENGINE SPEED SENSOR TEST . . . . . . . . . . . . 30
GLOW PLUG RELAY TEST . . . . . . . . . . . . . . . . 32
GLOW PLUG TEST . . . . . . . . . . . . . . . . . . . . . . 31
RELAYS—OPERATION/TESTING . . . . . . . . . . . . 32
VEHICLE SPEED SENSOR TEST . . . . . . . . . . . . 34
REMOVAL AND INSTALLATION
A/C CLUTCH RELAY . . . . . . . . . . . . . . . . . . . . . 34
ASD RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
ENGINE COOLANT TEMPERATURE SENSOR . . 34
ENGINE SPEED SENSOR . . . . . . . . . . . . . . . . . 34
GLOW PLUG RELAY . . . . . . . . . . . . . . . . . . . . . 35
GLOW PLUGS . . . . . . . . . . . . . . . . . . . . . . . . . . 34
POWERTRAIN CONTROL MODULE (PCM) . . . . 35
VEHICLE SPEED SENSOR . . . . . . . . . . . . . . . . 36
SPECIFICATIONS
GLOW PLUG CURRENT DRAW . . . . . . . . . . . . . 37
TORQUE CHART—2.5L DIESEL . . . . . . . . . . . . 37
im por t a n t t o kn ow t h a t t h e E CM h a s a fea t u r e
wh er e, if possible, it will ign or e t h e fa iled sen sor, set
a code r ela t ed t o t h e sen sor, a n d oper a t e t h e en gin e
in a "Lim p H om e" m ode. Wh en t h e E CM is oper a t in g
in a "Lim p H om e" m ode, t h e Ch eck E n gin e La m p on
t h e in st r u m en t pa n el m a y be con st a n t ly illu m in a t ed,
a n d t h e en gin e will m ost likely h a ve a n ot icea ble loss
of per for m a n ce. An exa m ple of t h is wou ld be a n
Acceler a t or P eda l P osit ion Sen sor fa ilu r e, a n d in t h a t
sit u a t ion , t h e en gin e wou ld r u n a t a con st a n t 1100
RP M, r ega r dless of t h e a ct u a l posit ion of t h e peda l.
Th is is t h e m ost ext r em e of t h e t h r ee "Lim p H om e"
m odes.
Wh en t h e Ch eck E n gin e La m p is illu m in a t ed con -
st a n t ly wit h t h e key on a n d t h e en gin e r u n n in g, it
u su a lly in dica t es a pr oblem h a s been det ect ed som e-
14 - 23
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