MITSUBISHI 3000GT 1991 Service Manual

ENGINE CONTROL - Specifications / Troubleshooting13-155
ENGINE CONTROL
i; SPECIFICATIONSSERVICE SPECIFICATIONS
M13CEB
IItems
Standard value
Accelerator cable playmm (in.)


Accelerator switch switching pointmm (in.)
TROUBLESHOOTING
Specifications
1
- 2 (.04 - .08)
3-5(.12-.20)
2 - 6 (08 - .24)ACCELERATOR CABLE AND ACCELERATOR PEDAL
MlSEGAC
ISymptomProbable causeRemedyI
Throttle valve will notfully open or closeMisadjusted accelerator cable
Misadjusted automatic speed-control cable
Broken return spring
Throttle lever malfunction
Adjust
Adjust
Replace
Replace
Accelerator pedaloperation not smooth(over acceleration)
Accelerator pedal wrongly tightened
Misinstalled accelerator cable
Accelerator cable requires lubricationRepair
Repair
Lubricate or replace
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13-156ENGINE CONTROL - Service Adjustment Procedures
SERVICE ADJUSTMENT PROCEDURES
M13FBCKIACCELERATOR CABLE INSPECTION AND
a ’ADJUSTMENT
For models equipped with the cruise control system, refer to
P. 13-l 58.(1) Turn air conditioner and lights OFF.
Inspect and adjust at no load.
(2) Warm engine until stabilized at idle.
(3) Confirm idle speed is at prescribed rpm.
(4) Stop engine (ignition switch OFF).
(5) Confirm there are no sharp bends in accelerator cable.
(6) Check inner cable for correct slack.
(7) If there is too ‘much slack or no slack, adjust play by the
following procedures.@ Turn the ignition switch to the ON position (without
starting the engine) and leave in that condition for
approximately 15 seconds.@Loosen the adjusting bolts on the air intake plenum, and
then secure the outer cable so that the free play of
th,einner cable will be the standard value.
Standard value:
1 - 2 mm (.04 - .08 in.)3-5 mm
(.12-.20 in.)
NOTE
\JIf there is excessive play of the accelerator cable, the
vehicle speed drop (“undershoot”) when climbing a slope
will be large.
If there is no play (excessive tension) of the accelerator
cable, the idling speed will increase.
(8) After adjusting, confirm that throttle valve fully opens and
closes by operating pedal.
(9) Adjust accelerator cable play and confirm throttle lever
stopper touches the fixed SAS.
ACCELERATOR SWITCH INSPECTION AND
A
nADJUSTMENTMlBFlBC
09FO117Make sure that when the accelerator pedal is free, there is
;$ustingcontinuity between the terminals of the accelerator switch and
/that when the pedal is pressed until the indicated pedal stroke
A reaches the standard value, there is no continuity between
the terminals of the switch.
Standard value:Accelerator switch switching point
2 - 6 mm (.079 - .24 in.)If stroke A is out of specification, adjust with adjusting bolt.
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ENGINE CONTROL - Engine Control13-157
ENGINE CONTROLREMOVAL AND INSTALLATION
L’
/
ii5Nm
4
ftlbs.1
/
Removal steps
I. Adjusting bolt2. Connection of throttle body side inner cable
3. Bushing
4. Accelerator cable
5. Accelerator
oedal6. Spring ’7. Connection of accelerator switch connector8. Accelerator arm bracket9.Split pin10.Accelerator arm11.Return spring12. Accelerator switch 13. Accelerator arm stopper14.Bolt 15.StopperMl30A-
-Post-installation Operation
l Accelerator Cable Adjustment
(Refer to P. 13-156.)l Accelerator Switch Adjustment 07A0031INSPECTION
MlBOCAJl Check the inner and outer cable for damage.
l Check the cable for smooth movement.
l Check the accelerator arm for bending.
l Check the return spring for deterioration.
l Check the connection of bushing to end metal fitting.
l Check the accelerator pedal switch for correct ON-OFF
switching.

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13-158CRUISE CONTROL SYSTEM - Specifications
CRUISE CONTROL SYSTEM
SPECIFICATIONSLJGENERAL SPECIFICATIONS
MlOCA-.Rated load A
Voltage drop V
Auto-cruise control switchRated load A
SET
Stop light switch (for cruise control)Rated load A
Clutch switchRated load A
Vacuum pump
TypeRated load A
Control valve, release valveSERVICE SPECIFICATIONS
MlBCB- -
ItemsI Specifications
Accelerator cable playmm (in.)

Throttle cablemm (in.)
Cruise control cablemm (in.)
Resistance between terminals for control valve and reliefvalve in vacuum pumps1
O-l (O-.04)
2-3(.08-.12)
1-2 (.04-.08)
l-2(.04-.08)
50-60
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CRUISE CONTROL SYSTEM - SDecialTools / Troubleshootina13-159
SPECIAL TOOLS
ToolNumber
Name1 Use
MB991341Multi-use testerassemblyl Checking of the self-diagnosis output
MB991 359
ROM pack
TROUBLESHOOTINGMlSEBDWPRELIMINARY INSPECTION
Check the following points and repair defective points, if any, before troubleshooting.
(I) Check that the vacuum pump assembly, link assembly, actuator and all cables and vacuum hoses are
properly installed and that the cables and vacuum hoses are correctly routed.
(2) Check that the link assembly and all cables move smoothly.
(3). Check each of the cables for excessive play or tension.
TROUBLESHOOTING QUICK REFERENCE CHART
Cruise control system is canceled when
cancellation not wanted.
Or, the cruise control system cannot be set after
an automatic cancellation.

Based on the diagnosis output code, check thecircuit and individual parts. (Refer to P.13-173.)
Can cruise control be set at the present moment?- Refer to section on trouble symptoms, “Cruisecontrol cannot be set.” (Refer to P. 13-l 60.)
Does the same problem occur again?
No
Check the diagnosis output. (Refer to P.13-176.)
> AUTO CANCEL activated during operation on asteep slope, or a temporary loose contact in theconnector
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13-160CRUISE CONTROL SYSTEM - Troubleshooting
NOTECruise control system cannot be set.This chart contains troubleshooting procedures to
perform when a problem cannot be detected by
self diagnosis.
Check input. (Refer to P. 13-l 73.)
I
Yes
Is the result of input check O.K.?
!
b Check vacuum pump assembly circuit.(Refer to P. 13-l 67.)
NoNOTEIf the results of checks on the vacuum pumpassemblv circuit and actuator parts (refer to P.13-184.)indicate that they are good, replace the control unit
pen
circurt In contraeplace controlswitch
Defective clutch switchReplace clutch switch
Even when select lever isplacedin
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CRUISE CONTROL SYSTEM - Troubleshootina13461
Trouble symptom
l The set vehicle speed variesgreatly upward or downward.l “Hunching” (repeated alter-
nating acceleration and
deceleration) occurs after
setting is made.
Probable cause
Check chart No.Remedy
Malfunction of the vehicleNo. 4Repair the vehicle speedspeed sensor circuit
sensor system, or replacethe part.Malfunction of thespeedometer cable orspeedometer drive gear
Vacuum pump assembly
No. 5Repair the actuatorcircuit poor contact
system, or replace thepart.Malfunction of thevacuum pump assembly
(including air leaks from
negative pressure
passage)
The cruise control system is notcanceled when the brake pedal
is depressed.Malfunction of the ECU
-Replace the ECU.
Brake switch (for cruiseNo. 6Repair the harness or
control) malfunction
replace the stop light
(short-circuit)switch.
Vacuum pump assemblyNo. 5Repair the harness ordrive circuit short-circuitreplace the vacuum pump
assembly.
The cruise control system is notcanceled when the clutch pedalis depressed. (It is canceled, however, whenthe brake pedal is depressed.)Malfunction of the ECU
-Replace the ECU.
Damaged or disconnected
If the input checkRepair the harness, orwiring of clutch switchcode No. 26 indicatesrepair or replace the clutch
input circuita malfunction.switch.No. 7Clutch switch improper
installation (won’t switch
ON)
Malfunction of the ECU-Replace the ECU.
The cruise control system is notDamaged or disconnectedIf the input checkRepair the harness, or
canceled when the shift lever iswiring of inhibitor switchcode No. 26 indicatesrepair or replace themoved to the “N” position.
input circuita malfunction.inhibitor switch.
(It is canceled, however, when
No. 8
the brake pedal is depressed.)Improper adjustment of
inhibitor switch
Cannot decelerate by using the
SET switch.Malfunction of the ECU
Temporary damaged ordisconnected wiring of
control switch input
circuit
-
No. 2Replace the ECU.
Repair the harness orreplace the control switch
Vacuum pump assemblyNo. 5Repair the harness orcircuit poor contactreplace the vacuum puml:assembly.
Malfunction of thevacuum pump assembly
Malfunction of the ECU
-Replace the ECU.
NOTEECU: Electronic control unit
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13-162CRUISE CONTROL SYSTEM - Troubleshooting
Trouble symptomProbable causeCheck chart No.
Remedy
Cannot accelerate or resume speedOpen or short circuit in
No. 2by using the RESUME switch.RESUME switch circuit inReplace the control switch
control switch
Vacuum pump assemblyNo. 5circuit poor contactRepair the harness or
replace the vacuum pump
Malfunction of thevacuum pump assembly
(including air leaks
from negative pressurepassage)assembly.
Malfunction of the ECU-Replace the ECU.
Even when CANCEL switch is set toON, cruise control is not canceled
Open or short circuit
in CANCEL switchIf the input check
Replace the control switch
(Cruise control, however, iscode No. 27 indicatescircuit in control switch
canceled when brake pedal isa malfunction.
depressed.)No. 2
Malfunction of the ECU-Replace the ECU
The cruise control system can be set
Malfunction of theNo. 4while traveling at a vehicle speedvehicle-speed sensorRepair the vehicle speed
of less than 40 km/h (25 mph), or
circuitsensor system, or replace
there is no automatic cancellationthe part.
at that speed.Malfunction of thespeedometer cable orthe speedometer drive
gear
Malfunction of the ECU
-Replace the ECU.
The cruise control indicator light
No. 3
of the combination meter does notDamaged or disconnectedbulb of indicator lightRepair the harness or
illuminate. (But cruise controlreplace the light bulb.
system is normal)Harness damaged or
disconnected
Malfunction of the ECU
-Replace the ECU.
Cruise control ON indicator light
No. 3
does not come on. (However, cruiseBurned-out indicator lightbulbRepair the harness or
control is functional.)replace the main switch.
Open or short circuit in
harness
Malfunction of control functionby
ON/OFF switching of ELC 4 AA
accelerator switch.
(Non-operation of damper clutch,
2nd gear hold, etc.)
Overdrive is not canceled during
fixed speed driving
No shift to overdrive during
manual driving.
Malfunction of circuitrelated to acceleratorswitch OFF function
Malfunction of the ECU
Malfunction of circuit
related to overdrive
cancellation, or mal-
function of ECU
No. IO
No. 11Repair the harness or
replace the part.
Repair the harness or
replace the part.
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CRUISE CONTROL SYSTEM - Troubleshooting13-163CHECK CHART
it l/Inspection of control unit power supply circuit
L;
,/
id
CRUISE#fi$ROL
0
SWITCH
“71
TROUBLESHOOTING HINTSECU terminal voltage
DESCRIPTION OF OPERATIONThe power is supplied through the ignition switch
(IG,) and cruise control main switch to the control
unit.
1. When the cruise control main switch is set to
ON with the ignition switch at ON, the current
from switch
S, flows through relay Ry, in the
switch. Accordingly, the contact of relay
Ry, is
closed and the power is supplied to the control
unit.
2. When the main switch is released, it automati-
cally returns to the neutral position. Since the
current from switch
S2 flows to relay Ry,, the
contact of relay Ry, remains closed.
3.When the main switch is set to OFF, current to
relay
Ry, is interrupted. This opens the contact
of relay
Ry, to stop the power supply to the
control unit. When the switch is released, it
automatically returns to the neutral position, but
relay Ry, stays in the OFF state.
4. When the ignition switch is set to OFF while
relay Ry, in the main switch is ON, relay
Ry, is
forced to the OFF state just like when the main
switch is set to OFF. Even if the ignition switch
is set to ON again, relay
Ry, stays in the OFF
state until the main switch is set to ON.
NOTEThe numbers beside each connector correspond
to those in the section
(P.13-176) “HARNESS
AND COMPONENTS LAYOUT”
TerminalNo.Signal nameCondition
I
TerminalvoltageI
2Control unit power supplyMain switch ON and neutral positionSystem voltage
thereafter
Main switch OFF and neutral positionov
thereafter8, 14
Control unit groundAt all timesov
16Control unit back up power supplyAt all timesSystem voltage
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13-164CRUISE CONTROL SYSTEM - Troubleshooting
2Inspection of control switch circuit
IGNITIONSWITCHtACC)
*X35-AK-R1302r-
._--------
LE- @CONTROL UNIT
TROUBLESHOOTING HINTSECU terminal voltage
DESCRIPTION OF OPERATIONdThe control switch is a switch in which the SET,
RESUME and CANCEL switches are integrated.
Therefore, different resistance values are used for
the individual switches to change the outputs
(voltages) to the control unit. Current flows through
fuse No. @ of J/B and through the control switch to
the control unit.
1. SET switchWhen the cruise control switch is ON, if the SET
switch is set to ON while vehicle speed is within
a range from about 40 to 145 km/h (25 to 90
mph), the vehicle starts cruising at the speed. If
the SET switch is kept at ON during cruise
operation, the vehicle coasts, and starts cruising
at the speed reached when the SET switch is
set to OFF.
2. RESUME switch
Even if cruise operation is canceled, the vehicle
resumes cruising at the speed set before the
cancellation. Both when the main switch is set
to OFF and when the vehicle speed is reduced
to less than 40 km/h (25 mph) , the vehicle will
not resume cruising at the previously set speed
even if the RESUME switch is set to ON. If the
RESUME switch is kept at ON during cruise
LJoperation, the engine accelerates, and the vehi-
cle starts cruising at the speed reached when
the RESUME switch was set to OFF. (However,
when the vehicle speed is raised to more than
145 km/h (90 mph), the vehicle cruises at
approximately 145 km/h {90 mph).
3. CANCEL switch
When the CANCEL switch is set to ON during
cruise operation, the cancel signal is input to the
control unit which internally interrupts the power
supply to the vacuum pump assembly for
cancellation of cruise operation.
18Control switchSignal name
L
Condition
I
Terminalvoltage1
When all switches are OFFIov1
When SET switch is ONI3vI
When RESUME switch is ON
When CANCEL switch is ON6Vd
Systemvoltage
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