1991 MITSUBISHI ECLIPSE sensor

14-112AUTO-CRUISE CONTROL SYSTEM - Troubleshootina
Trouble symptomProbable causeCheck chart No.Remedy
l The set vehicle speed variesMalfunction of the vehi-No.4Repair the vehicle speec
greatly upward or downward.cle speed sensor circuitsensor system, or re-l “Hunching”
(repeated alternatingplace the part.
acceleration and deceleration)Malfunction of the
occurs after setting is made.speedometer cable orspeedometer drive gearAuto-cruise
vacuumNo.5Repair the auto-cruise
pump circuit poor con-vacuum pump, ortactreplace the part.Malfunction of the
auto-
cruise vacuum pumpMalfunction of the
ECU-Replace the ECU.
The auto-cruise control system is notDamaged or discon-If the input check codeRepair the harness or
canceled when the brake pedal isnetted wiring of theNo. 23 indicates a mal-replace the stop light
depressed.stop light switch inputfunction. No. 6switch.circuit; brake switch (forauto-cruise control) mal-function (short-circuit)Auto-cruise
vacuumNo. 5Repair the harness or
pump drive circuit short-replace the auto-cruisecircuitvacuum pump.Malfunction of the
ECU-Replace the ECU.
The auto-cruise control system is notDamaged or discon-If the input check codeRepair the harness, or
canceled when the clutch pedal isnetted wiring of clutchNo. 26 indicates a mal-repair or replace the
depressed. (vehicles with a manualswitch input circuitfunction. No. 8clutch switch.
transaxle)(It is canceled, however, when theClutch switch improper
brake pedal is depressed.)installation (won’tswitch ON)Malfunction of the
ECU-Replace the ECU.
The auto-cruise control system is notDamaged or discon-If the input check codeRepair the harness, orcanceled when the shift lever isnetted wiring of inhibi-No. 26 indicates a mal-repair or replace the in-
moved to the “N” position. (vehiclestor switch input circuitfunction. No.7hibitor switch.llvith an automatic transaxle)
[It is canceled, however, when theImproper adjustment of
Drake pedal is depressed.)inhibitor switchMalfunction of the
ECU-Replace the ECU.
Cannot decelerate by using the SETTemporary damaged orNo. 2Repair the harness orswitchdisconnected wiring ofreplace the SET switch.SET switch input circuitAuto-cruise
vacuumNo.5Repair the harness orpump circuit poor con-replace the auto-cruisetactvacuum pump andactuator.Malfunction of the auto-cruise vacuum pump
and actuator (includingclogging of negativepressure passage)Malfunction of the
ECU-Replace the ECU.

.z
c-AUTO-CRUISE CONTROL SYSTEM
- Tr6ubleshootina
Trouble symptom
Cannot accelerate or resume speed
by using the RESUME switch.
Probable cause
Damaged or discon-netted wiring, or short-circuit, of
RESUMEswitch input circuit
Remedy .’ ’-c liiCheck chart No.,;+ >,, a”:; : :
9 . /~ A%No.3.Repair theharness‘&
replace the RESUMEswitch.Auto-cruise
vacuumNo. 5Repair the harness orpump circuit poor con-replace the auto-cruisetact
vacuum,pump andactuator.Malfunction of the auto-cruise vacuum pumpand actuator (includingair leak from negativepressure passage)Malfunction of the
ECU.-Replace the ECU.
Auto-cruise control system can beMalfunction of theNo.4Repair the vehicle-set while
traveling at a vehicle speedvehicle-speed sensorspeed sensor system,
of less than 40 km/h (25 mph), orcircuitor replace the part.there
is no automatic cancellation atthat
speed.Malfunction of the‘I,speedometer cable orthe speedometer drive6 i
gear
The indicator light of combination
meter does not illuminate.
(But auto-cruise control system is
normal.)Malfunction
of control function by
ON/OFF switching of ELC 4 A/T
accelerator switch,Non-operation of damper clutch,
2nd gear hold, etc.)3verdrive
is not canceled during
‘ixed speed driving.
10 shift to overdrive during manual
driving. Malfunction of the
ECU-Replace the ECU.
Damaged or discon--Repair the harness or
netted bulb of indicatorreplace the bulb.light
Harness damaged ordisconnected
‘._,.Malfunction of circuit
re-No. 9Repair the harness or
lated to acceleratorreplace the part.switch
OFF functionMalfunction of the
ECUMalfunction of circuit
re-No. 10Repair the harness or
lated to overdrive can-replace the part.
cellation, or malfunction
of ECU

AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
3. CHECKING THE RESUME SWITCH CIRCUIT.
” ,, . .
Auto-cruisecontrol unit
Cruise-controlswitchDescription of operation
The set speed (before cancellation) resumes when the RE-SUME switch is switched ON, even if the constant-speed
control has been cancelled.That speed will not resume, however, even if the RESUME
switch is switched ON, if the CRUISE switch is switched OFF
and if the vehicle speed decreases to 40 km/h’
(25 mph) or
lower.
In addition, when the RESUME is switched ON and held while
the vehicle is traveling at a constant speed, the vehicle speed
will increase; the speed at which the switch is subsequently
released will become the newly set constant speed.Current flows to the control
unit, the cruise control switch
(RESUME), and to ground.
Troubleshopting hint
Diagnosis-No. 15
(automatica& canceelied)ECU terminal voltage
Tez3!alSignalConditionsTerminalvoltage
18RESUMEWhen the RESUMEOVswitchswitch is,switchedON.
When the RESUME
“o”;:“h IS swrtched;;;;g;
\ ‘)
13AO365,,4. CHECKING THE VEHICLE-SPEED SENSOR CIRCUIT
Auto-cruisecontrol unit
Combination
meter
Junction
block
13A0366Description of operation
The vehicle-speed sensor is installed within the sljeedometer; it
sends to the control unit pulse signals that are proportional to
the rotation speed (i.e., the vehicle speed) of the transaxle’soutput gear.
This vehicle-speed sensor is the reed switch type of sensor; it
generates four pulse signals for each rotation of the speedo-
meter’s driven gear.Troubleshooting hint
Diagnosis-No. 12 (automatically
cancelled)ECU terminal voltage
Move the vehicle
forward slowly.

14-118AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
8. CHECKING THE CLUTCH SWITCH CIRCUIT
Auto-cruisecontrolunit9
2ClutchswitchOFF ON
1m11Junction
blockI
13AO370Description of operation
If the clutch pedal is pressed wht driving at a constant speed,
the clutch switch is turned ON and a cancel signal is input to the
control unit and the determined driving speed is canceled
because current flows to the clutch, switch junction block from
the control unit and to ground.Troubleshooting hint
ECU terminal voltage
TerminalSignal
No.
1Clutch switch
t--l--II
ConditionsTerminalvoltage
When the clutch
pedal is depressed.
When the clutchpedal is not de-
pressed.
9. CHECKING THE CIRCUITS RELATED TO THE ACCELERATOR SWITCH OFF FUNCTION
Ignition switchm
& Accel-/Description of operation
The accelerator switch is a switch that detects the operationalstatus of the accelerator pedal; it is one of the sensors of theautomatic, transaxle.Because the status of the accelerator pedal during constant-speed driving is non-operational, the ground circuit (transistorTr2) of the accelerator switch is switched OFF only during
constant-speed driving in order not to interfere wtth the function
of the automatic transaxle.Troubleshooting hint
ECU terminal voltage
TerminalNo.SignalConditionsTerminalvoltaoe
’ 3Control unitAt all times
power supply
9Accelerator
When the accel-ovswitcherator pedal is
depressed.
When the accel-Systemerator pedal is not
depressed.voltage
\lOTEJC: Indicates ON at all time.
13AO3711 Not in operation ) OFF 1 ON (

14-120AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
11. CHECKING THE THROTTLE POSITION SENSOR AND IDLE SWITCH CIRCUIT<1.8L Engine>
Throttle
position
sensor
MPI controlunitnw374<2.0L DOHC Engine>
ruiseI unitDescription of operation
“s
The throttle position sensor and idle switch are mounted in the,
motor position sensor or throttle body and are sensors in theMPI system. The idle switch is turned OFF when the accelera-
tor pedal is pressed and ON when it is released. In addition,
throttle position sensor output voltage varies according to thedegree of opening of the throttle valve.Troubleshooting hint

Diagnosis-No. 17

Diagnosis-No. 17
ECU terminal voltageTeKlna’
SignalConditionsTerminal
voltage
4Idle switchWhen accelerator
pedal is pressedXFgr
When acceleratorovpedal is released
5ThrottleWhen accelerator 4.OV-5.5V
position sensorpedal is pressedall the way down
When accelerator 0.48-0.72Vpedal is released

14-122AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
DIAGNOSIS DISPLAY PAlTERNS AND CODES
CodeNo.
11
Display patterns (output codes)(Use with voltmeter)
“,;1 fl 1 j--
Probable cause
Abnormal condition of auto-cruise
vacuum pump drive system
Check chart No.
No. 5
12Abnormal condition of vehicle-speed sig-No.4nal system
15"16"12vControl switch malfunction (when SETNo.2, 3
and RESUME switches switched ONovsimultaneously for more than 25 seconds)
I ‘,“,-I r
Abnormal condition of auto-cruiseNo.6,7,8control unit
17Abnormal condition of throttle positionNo. 11
sensorAbnormal condition of idle switch,3*0356
NOTE
1. Codes indicated by the* symbol are displayed, if the conditions are satisfied, even if the system is
normal. In either case, the system is normal if it can be reset. If there is an automatic cancellation not
intentionally made by the driver, however, excluding cancellations explicitly made by the cancel
procedure, there may be a temporary malfunction such as poor contact of a harness connector even
though the system can be reset, and for that reason it is necessary to check according to each
individual check chart that is applicable.Display
when vehicle speed isapproximately 20 km/h (12 mph) less thanor before the auto-cruise control systemis set
ON (12V)
OFF (OV)2. Diagnosis codes are displayed when, after cancellation of
the auto-cruise control system, the vehicle speed
de-creases to less than approximately 20 km/h (12 mph), and
are canceled by turning OFF the battery or canceling the
diagnosis codes. (Refer to
P.14-121.)After the diagnosis codes in the memory are erased, if
(when the power supply of the electroinc control unit is
switched ON once again) the power supply of the
electronic control unit is normal, the diagnosis output
code display will be as below, regardless of whether the
system condition is normal or not.
Continuous ON/OFF signals will be displayed at 0.5-second
intervals.(Refer to the figure at the left.)

14-124AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
INPUT CHECK TABLE
CheckInput operationiI!eDisplay patterns (output codes)Check results
No.(use with voltmeter)
1SET switch ON21X:Gayitch circuit
2RESUME switch ON2212vRESUME switch cir-cuit
normalov
3Stop light switch ON (brake23
pedal depressed)
;;pl;yht switch
4Driving at approximately to 4024When both No. 4
km/h (25 mph) or higherand No. 5 can be
co,nfirmed, vehicle-.speed sensor circuit
5Driving at less than approx-2512vnormal.
imately 40 km/h (25 mph) or
stopped
ov
61. Clutch switch ON (clutch26Clutch switch inhibi-
pedal depressed) tor switch normal
2. Inhibitor switch ON (shift12vlever to “N” or “P” range)ov
-aIT>
7Throttle position sensor output28
voltage over 1.5V (when theThrottle positionsensor normal
accelerator pedal is pressedmore than half way)
?Idle switch OFF (accelerator29Idle switch normal
pedal depressed)
NOTE
1.Each code will be displayed in an order ofpriority beginning from No. 1.
If there is no display, it is possible that
there is a malfunction of the ECU power-
supply circuit or the SET and/or RESUMEswitch, so check according to check
charts
1,2 and 3.
2. Continue each input operation until the
output code is emitted.
If no output codes are emitted for inputs
even though the display pattern is repe-
ated two or more times, there is a
malfunction of the switch sensor.
3.When each input operation is performed and
the signals for the conditions are received by
the computer, each output code will be
repeatedly displayed in the sequence of
priority for as long as that signal continues.
4.If, during the display of output codes, the
input operation is canceled (if, for example,
the SET switch is set from ON to OFF), the
code will be displayed for one cycle of the
display, but will not be displayed during the
next cycle.
This makes it possible, therefore, to check
the OFF condition (existence of not of a
short-circuit of the input line or the switch).

AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
AUTO-CRUISE CONTROL RELATED HARNESSES

1? 3
10 11
Ground Point
--
, ’
112 I$ ii 15r is i72OAO402
1. Idle switch <2.0L DOHC engine>
2. Motor position sensor (Idle switch) engine’>3. Auto-cruise control vacuum pump4. Throttle position sensor5. Starter motor6. Inhibitor switch 7. Auto-cruise control unit8.Junction block9.Self-diagnosis connector10.Clutch switch
11. Stop light switch12.Ignition switch
13.Column switch14. Accelerator switch 15. Power/Economy changeover switch
16. Overdrive switch 17. MPI control unit
18. 4Aff control unit
NOTERefer to P.14-126 for details about the mounting positicjkof
the auto-cruise control unit, etc.Junction Block
NoconnectionFront side
,-To engineroom
To instrumentRear side
)To bodywiringharness