MITSUBISHI TRITON 1997 Workshop Manual

MPI ± Troubleshooting13A-18
Code No. 25 Barometric pressure sensor systemProbable cause
Range of Check

Ignition switch: ON

Excluding 60 seconds after the ignition switch is turned to ON or immediately
after the engine starts.

Battery voltage is 8 V or more.
Set conditions

Sensor output voltage is 4.5 V or more (corresponding to a barometric pressure
of 114 kPa or more) for 4 seconds.
or

Sensor output voltage is 0.2 V or less (corresponding to a barometric pressure
of 5.33 kPa or less) for 4 seconds.
Malfunction of the barometric pressure sensor

Improper connector contact, open circuit or
short-circuited harness wire of the barometric pressure
sensor circuit

Malfunction of the engine-ECU
Measure at the air flow sensor con-
nector A-77.

Connect the connector. (Use
the test harness: MB991348)

Voltage between 2 and earth
(Ignition switch: ON)
OK:3.7 ± 4.3 V (Altitude: 0 m)
3.2 ± 3.8 V (Altitude:
1,200 m)NGMeasure at the air flow sensor con-
nector A-77.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:4.8 ± 5.2 V

Continuity between 5 and earth
OK:ContinuityNGCheck the following connector.
C-51NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector.
A-77NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
OK
Replace the air flow sensor.
OK
Measure at the engine-ECU con-
nector C-51.

Connect the connector.

Voltage between 65 and earth
(Ignition switch: ON)
OK:3.7 ± 4.3 V (Altitude: 0 m)
3.2 ± 3.8 V (Altitude:
1,200 m)NGCheck the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector, and
repair if necessary.
Check the following connector.
C-51
OK
Check trouble symptom.
NG
Replace the engine-ECU.NG
Repair OK

MPI ± Troubleshooting13A-19
Code No. 36 Ignition timing adjustment signal systemProbable cause
Range of Check

Ignition switch: ON
Set conditions

The ignition timing adjusting signal wire is shorted to the earth.
Short circuit to earth of the ignition timing adjustment
signal line

Malfunction of the engine-ECU
Measure at the ignition timing adjust-
ment connector A-42.

Measurement of the voltage (Ignition
switch: ON)
OK:4.0 ± 5.2 VNGCheck the following connector. C-50NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the
engine-ECU connector and the ignition
timing adjustment terminal.NG
Repair
OK
Replace the engine-ECU.
OK
Replace the engine-ECU.
Code No. 41 Injector systemProbable cause
Range of Check

Engine speed is approx. 50 ± 1,000 r/min

The throttle position sensor output voltage is 1.15 V or less.

Actuator test by MUT-II is not carried out.
Set conditions

Surge voltage of injector coil is not detected for 4 seconds.
Malfunction of the injector

Improper connector contact, open circuit or
short-circuited harness wire of the injector circuit

Malfunction of the engine-ECU
Check the injector. (Refer to P.13A-89.)NG
Replace
OK
Measure at the injector connectors.
A-45, A-46, A-57, A-61.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:System voltageNGCheck the following connectors.
A-45, A-46, A-57, A-61.NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
engine-ECU and the injector connector,
and repair if necessary.
Check the injector control circuit.
(Refer to P.13A-55, INSPECTION PRO-
CEDURE 47.)OK

MPI ± Troubleshooting13A-20
Code No.54 Immobilizer systemProbable cause
Range of Check

Ignition switch: ON
Set Conditions

Improper communication between the engine-ECU and immobilizer-ECU
Radio interference of ID codes

Incorrect ID code

Malfunction of harness or connector

Malfunction of immobilizer-ECU

Malfunction of engine-ECU
NOTE
(1) If the ignition switches are close each other when starting the engine, radio interference may cause
this code to be displayed.
(2) This code may be displayed when registering the key ID code.
No
Is there another ignition key near the ignition key that is inserted
in the ignition switch?Ye sRemove the extra ignition key.
NGCheck trouble symptom.
Is a diagnosis code output from the immobilizer-ECU?Ye sCheck the immobilizer system. (Refer to GROUP 54 ± Ignition
Switch and Immobilizer System.)
No
Check the following connectors.
C-19, C-36, C-50NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the engine-ECU and the immobiliz-
er-ECU.OKReplace the immobilizer-ECU.
NG
Check trouble symptom.NG
RepairNG
Replace the engine-ECU.

MPI ± Troubleshooting13A-21
INSPECTION CHART FOR TROUBLE SYMPTOMS13100880217
Trouble symptomInspection
procedure
No.Reference page
Communication
with MUT-IIis
Communication with all systems is not possible.113A-23
with MUT-II is
impossible.
Communication with engine-ECU only is not possible.213A-24
Engine warning
lamp and
relatedparts
The engine warning lamp does not illuminate right after the
ignition switch is turned to the ON position.313A-25
related partsThe engine warning lamp remains illuminating and never goes
out.413A-25
StartingNo initial combustion (starting impossible)513A-26
Initial combustion but no complete combustion
(starting impossible)613A-27
Long time to start (improper starting)713A-28
Idling stability
(Improper idling)
Unstable idling (Rough idling, hunting)813A-29
(Im ro er idling)
Idling speed is high. (Improper idling speed)913A-30
Idling speed is low. (Improper idling speed)1013A-31
Idling stability
(Engine stalls)
When the engine is cold, it stalls at idling. (Die out)1113A-32
(Engine stalls)
When the engine becomes hot, it stalls at idling. (Die out)1213A-33
The engine stalls when starting the car. (Pass out)1313A-34
The engine stalls when decelerating.1413A-34
DrivingHesitation, sag or stumble1513A-35
The feeling of impact or vibration when accelerating1613A-35
The feeling of impact or vibration when decelerating1713A-36
Poor acceleration1813A-36
Surge1913A-37
Knocking2013A-37
Dieseling2113A-37
Too high CO and HC concentration when idling2213A-38

S
ym pto m S
ta rtin g W
on't s ta rt T
he s ta rte r is u se d to c ra nk th e e ngin e, b ut th ere is n o c o m bustio n w it h in th e
c ylin ders , a nd th e e ngin e w on't s ta rt. F
ir e s u p a nd d ie s T
here is c o m bustio n w it h in th e c ylin ders , b ut th en th e e ngin e s o on s ta lls . H
ard s ta rtin g E
ngin e s ta rts a fte r c ra nkin g a w hile . I
d lin g s
ta bilit y H
untin g E
ngin e s p eed d oesn 't r e m ain c o nsta nt; c h anges a t id le . s
ta bilit y R
ough id le U
su ally , a ju dgem ent c a n b e b ase d u pon th e m ove m ent o f th e ta ch om ete r
p oin te r, a nd th e v ib ra tio n tr a nsm it te d to th e s te erin g w heel, s h if t le ve r, b ody, e tc .
T his is c a lle d r o ugh id le . I
n co rre ct id le s p eed T
he e ngin e d oesn 't id le a t th e u su al c o rre ct s p eed. E
ngin e s ta ll
( D ie o ut) T
he e ngin e s ta lls w hen th e fo ot is ta ke n fr o m th e a cce le ra to r p edal, r e gard le ss
o f w heth er th e v e hic le s is m ovin g o r n ot. E
ngin e s ta ll
( P ass o ut) T
he e ngin e s ta lls w hen th e a cce le ra to r p edal is d epre sse d o r w hile it is b ein g
u se d. D
riv in g H
esit a tio n S ag ª
H esit a tio nº is th e d ela y in r e sp onse o f th e v e hic le s p eed ( e ngin e s p eed) th at
o ccu rs w hen th e a cce le ra to r is d epre sse d in o rd er to a cce le ra te fr o m th e s p eed
a t w hic h th e v e hic le is n ow tr a ve lin g, o r a te m pora ry d ro p in v e hic le s p eed
( e ngin e s p eed) d urin g s u ch a cce le ra tio n.
S erio us h esit a tio n is c a lle d ª s a gº. ( R efe r to F ig . 1 ) P
oor a cce le ra tio n P
oor a cce le ra tio n is in abilit y to o bta in a n a cce le ra tio n c o rre sp ondin g to th e
d egre e o f th ro ttle o penin g, e ve n th ough a cce le ra tio n is s m ooth , o r th e in abilit y
t o r e ach m axim um s p eed. S
tu m ble E
ngin e s p eed in cre ase is d ela ye d w hen th e a cce le ra to r p edal is in it ia lly
d epre sse d fo r a cce le ra tio n. ( R efe r to F ig . 2 ) S
hock T
he fe elin g o f a c o m para tiv e ly la rg e im pact o r v ib ra tio n w hen th e e ngin e is
a cce le ra te d o r d ece le ra te d. S
urg e T
his is r e peate d s u rg in g a head d urin g c o nsta nt s p eed tr a ve l o r d urin g v a ria ble
s p eed tr a ve l. K
nockin g A
s h arp s o und lik e a h am mer s tr ik in g th e c ylin der w alls d urin g d riv in g a nd w hic h
a dve rs e ly a ff e cts d riv in g. S
to ppin g R
un o n
( ª D ie se lin gº) T
he c o ndit io n in w hic h th e e ngin e c o ntin ues to r u n a fte r th e ig nit io n s w it c h is
t u rn ed to O FF. A ls o c a lle d ª D ie se lin gº.

MPI ± Troubleshooting13A-23
INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
INSPECTION PROCEDURE 1
Communication with MUT-II is not possible.
(Communication with all systems is not possible.)
Probable cause
The cause is probably a defect in the power supply system (including earth) for the
diagnosis line.
Malfunction of the connector

Malfunction of the harness wire
Measure at the diagnosis connector
(16-pin) C-35.

Voltage between 16 and earth
OK:Battery voltageNGCheck the following connectors.
A-56X, C-79, C-81NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
power supply and diagnosis connector
(16 pin), and repair if necessary.OK
Measure at the diagnosis connector
(16-pin) C-35.

Continuity between 4 and earth

Continuity between 5 and earth
OK:ContinuityNG
OK
Replace the MUT-II.
Check the following connector.
C-86NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
diagnosis connector (16-pin) and the
earth, and repair if necessary.

MPI ± Troubleshooting13A-24
INSPECTION PROCEDURE 2
MUT-II communication with engine-ECU is impossible.
Probable cause
One of the following causes may be suspected.

No power supply to engine-ECU.

Defective earth circuit of engine-ECU.

Defective engine-ECU.

Improper communication line between engine-ECU and MUT-II<Vehicles without immobilizer system>

Malfunction of engine-ECU power supply circuit

Malfunction of engine-ECU

Open circuit between engine-ECU and diagnosis
connector
<Vehicles with immobilizer system>

Malfunction of engine-ECU power supply circuit

Malfunction of engine-ECU

Malfunction of immobilizer-ECU

Open circuit between immobilizer-ECU and diagnosis
connector

Open circuit between engine-ECU and immobilizer-
ECU
OK
Ye s
NG
<Vehicles without immobilizer system>
Check the following connector. C-19NG
Repair
Check trouble symptom.
NG
Check the harness wire between engine-ECU and diagnosis con-
nector.OKCheck the harness wire
between engine-ECU and
earth.NG
Repair
OK
Check the power supply and ignition switch-IG system. (Refer to
P.13A-39, INSPECTION PROCEDURE 23.)
<Vehicles with immobilizer system>
Repair
OKCheck the harness wire
between engine-ECU and
earth.NG
Repair
OK
Check the power supply and ignition switch-IG system. (Refer to
P.13A-39, INSPECTION PROCEDURE 23.)
NG
Check the harness wire between engine-ECU and immobilizer-
ECU.
OK
Check trouble symptom.
Check the following connectors. C-19, C-36NG
Repair
Is communication possible between the MUT-II and the immobilizer-
ECU?NoCheck the diagnosis line between the immobilizer-ECU and the
MUT-II, and repair if necessary. (Refer to GROUP 54 ± Ignition
Key and Immobilizer.)
NG
Repair

MPI ± Troubleshooting13A-25
INSPECTION PROCEDURE 3
The engine warning lamp does not illuminate right after
the ignition switch is turned to the ON position.
Probable cause
Because there is a burnt-out bulb, the engine-ECU causes the engine warning lamp
to illuminate for five seconds immediately after the ignition switch is turned to ON.
If the engine warning lamp does not illuminate immediately after the ignition switch
is turned to ON, one of the malfunctions listed at right has probably occurred.
Burnt-out bulb

Defective warning lamp circuit

Malfunction of the engine-ECU
MUT-II Data list
16 engine-ECU power supply voltage (Refer to P.13A-58.)NGCheck the engine-ECU power supply and earth circuit.
(Refer to P.13A-53, INSPECTION PROCEDURE 42.)
OK
Measure at the engine-ECU connector C-50.

Disconnect the connector, and measure at the harness side.

Earth the terminal No. 36.
OK:The engine warning lamp illuminates.OKCheck the following
connector. C-50.NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.
NG
Check a burnt-out bulb.NG
Replace
OK
Measure at the combination meter connector C-06.

Disconnect the connector, and measure at the harness side.

Voltage between 43 and earth (Ignition switch: ON)
OK:System voltageNGCheck the engine warning lamp power supply circuit, and repair
if necessary.
OK
Check the following connectors.
C-04, C-06, C-19, C-50NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between combination meter and engine-
ECU, and repair if necessary.
INSPECTION PROCEDURE 4
The engine warning lamp remains illuminating and never
goes out.
Probable cause
In cases such as the above, the cause is probably that the engine-ECU is detecting
a problem in a sensor or actuator, or that one of the malfunctions listed at right has
occurred.
Short-circuit between the engine warning lamp and
engine-ECU

Malfunction of the engine-ECU
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13A-10, INSPECTION CHART FOR DIAGNOSIS
CODES
No
Measure at the combination meter connector C-04.

Disconnect the connector, and measure at the harness side.

Disconnect the engine-ECU connector

Continuity between 8 and earth
OK:No continuityNGCheck the harness wire between combination meter and engine-
ECU connector, and repair if necessary.
OK
Replace the engine-ECU.

MPI ± Troubleshooting13A-26
INSPECTION PROCEDURE 5
No initial combustion (starting impossible)
Probable cause
In cases such as the above, the cause is probably that a spark plug is defective,
or that the supply of fuel to the combustion chamber is defective.
In addition, foreign materials (water, kerosene, etc.) may be mixed with the fuel.
Malfunction of the ignition system

Malfunction of the fuel pump system

Malfunction of the injectors

Malfunction of the engine-ECU

Malfunction of the immobilizer system <only vehicles
with immobilizer system>

Foreign materials in fuel
Check battery voltage when cranking.
OK:8 V or higherNGCheck the battery. (Refer to GROUP 54 ± Battery.)
OK
Is immobilizer-ECU diagnosis code displayed? <only vehicles with
immobilizer system>Ye sCheck the immobilizer.
(Refer to GROUP 54 ± Ignition Key and Immobilizer.)
No
MUT-II: Inspection of no initial combustion.
(Refer to P.13A-47, INSPECTION PROCEDURE 34.)
OK
Can any sound be heard from the injectors when cranking?NGCheck the injector system. (Refer to P.13A-19, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
OK
Ignition system: Inspection of no initial combustion.
(Refer to P.13A-47, INSPECTION PROCEDURE 35.)
OK
Check the following items.

Check the ignition coil, spark plugs, spark plug cables. (Refer to GROUP 16 ± On-vehicle service.)

Check if the injectors are clogged.

Check if foreign materials (water, alcohol, etc.) got into fuel.

Check the compression pressure.

Check the immobilizer system. (Refer to GROUP 54 ± Ignition Key and Immobilizer.) <only vehicles with immobilizer system>

MPI ± Troubleshooting13A-27
INSPECTION PROCEDURE 6
Initial combustion but no complete combustion
(starting impossible)
Probable cause
In such cases as the above, the cause is probably that the spark plugs are generating
sparks but the sparks are weak, or the initial mixture for starting is not appropriate.
Malfunction of the ignition system

Malfunction of the injector system

Foreign materials in fuel

Poor compression

Malfunction of the engine-ECU
Check battery voltage when cranking.
OK:8 V or higherNGCheck the battery. (Refer to GROUP 54 ± Battery.)
OK
MUT-II: Check if uncompleted combustion occurs.
(Refer to P.13A-48, INSPECTION PROCEDURE 36.)
OK
Can any sound be heard from the injectors when cranking?NGCheck the injector system, (Refer to P.13A-19, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
OK
Is starting good if the engine is cranked with the accelerator pedal
slightly depressed?Ye sCheck ISC servo for op-
eration sound.
(Refer to P.13A-90.)NGCheck the ISC servo sys-
tem. (Refer to P.13A-45,
INSPECTION PROCE-
DURE 31.)
OK

Clean the throttle valve area. (Refer to P.13A-78.)

Check and adjust the fixed SAS. (Refer to P.13A-79.)
No
Check the ignition timing when cranking.
OK:Approx. 5BTDCNGCheck that the distributor is installed properly.
OK
Check the following items.

Check the ignition coil, spark plugs, spark plug cables. (Refer to GROUP 16 ± On-vehicle Service.)

Check if the injectors are clogged.

Check the compression pressure. (Refer to GROUP 11 ± On-vehicle Service.)

Check fuel lines for clogging.

Check if foreign materials (water, alcohol, etc.) got into fuel.