set MITSUBISHI GALANT 1989 Service Workshop Manual

13-334AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
TROUBLESHOOTIN
G
MlJEBDH

The auto-cruise control system performs control functions for
the setting or cancellation of the fixed-speed driving speed bas-
ed upon the data provided by input signals. As a result, when
the auto-cruise control system is canceled, the cause of the
cancellation is memorized in a separate circuit by the ECU,
regardless of whether or not the auto-cruise control system
condition is normal or abnormal, thus providing the ECU with
the on-board diagnostic function by certain fixed patterns, as
well as the function of being able to check whether or not the
ECU’s input switches or sensor are normal. Thus, by effectively
using these function, the time required checking and repair can
be shortened.
NOTE
When the computer (ECU) power supply (ignition switch andmain switch) is switched OF-F, the memorized diagnostic
trouble codes are erased, and so for this reason the power
supply must be left ON until the checking is completed.
TROUBLESHOOTING QUICK-REFERENCE CHART
when cancellation not wanted.
be set after an automatic cancellation. ECU: Electronic control unit
After the occurrence of the problem, wasYes. With the main switch ON and the engine
the ignition switch and main switch leftrunning, check the diagnostic trouble code.
ON?+ (P.13-361)
No
Can the auto-cruise control system be set
_r-l;
Yes
No (new normal)Check whether or not, then, the vehicle was driven on a
steep slope, or the SET and RESUME control switches
were operated simultaneously. (The cause is not clear
under the present circumstances.)
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AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
Auto-cruise control system cannot be set.
NOTE
If. after the occurrence of the problem, the ignition switch and
the main switch have not been switched OFF, it is possible to
Prepare to conduct input check.determine (by checking the on-board diagnostic output code)
which circuit canceled the system’s operation.
This chart is to be used, then, for troubleshooting if it is not possible
to use the on-board diagnostic for checking.
Were codes No. 21, 22 and 25 displayed when,with the vehicle stationary, the input check
codes were recalled?
Yes
No0 Damaged or disconnected wiring of the ECU power-supply cir--cuit (Go to check chart 1 on page 13-339.)l Damaged or disconnected wiring of the SET or RESUME switch(Go to check chart 2 and 3 on page 13-338.339.)
le results of all input checks normals?
YesNo
.t
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.
Check resultsProbable causeRemedyCheck chart
No.
Code 21 remains even though
SET switch is set to OFF. SET switch ON mal-Replace the control
No. 2
function switch.
SET switch input lineRepair the harness.
short-circuit
Code 22 remains even though RESUME switch is set to OFF.RESUME switch ON Replace the controlNo. 3
malfunction
switch.
RESUME switch inputRepair the harness.
line short-circuit
Code 23 remains even though
CANCEL switch is set to OFF. Malfunction of the
CANCEL circuit
(ON malfunction) Check or repair each
No. 6-1, 6-2,
CANCEL circuit.6-3
Code 25 does not disappear, and
Malfunction of the ve- Check or repair the No. 4
code 24 does not appear, even hicle-speed
sensor cir- vehicle speed sensor
though vehicle speed reaches ap-
cuit (damaged or dis-circuit.
proximately 40 km/h (25 mph) or connected wiring, or
higher.short-circuit)
ie actuator circuit.1NOTECheck tl(GO to check chart No.5 on page 13-343.)If the results of the check of the actuator circuit (check Chart
No.5) and of the actuator itself (P.13-396) reveal no abnormal
condition, replace the electronic control unit (ECU).

13-336AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
Probable cause1 Check chart No.1 Remedy
l The set vehicle speed variesMalfunction of the ve-No.4Repair the vehicle speec
greatly upward or downward.hicle speed sensor cir-sensor system, or re-l “Hunching” (repeated alternatingcuit place the part.
acceleration and deceleration) oc-
curs after setting is made.
Malfunction of the spee-dometer cable or spee-dometer drive gear
Actuator circuit poor
contact
Malfunction of the ac-
tuator
No.5Repair the actuator sys-tern or replace the part.
Malfunction of the ECU
-Replace the ECU.
The auto-cruise control system is notDamaged or discon-If the input check codeRepair the harness or re
canceled when the brake pedals isnetted wiring of the stopNo.23 indicates a mal- place the stop light
depressed.light switch input circuit; function. No.6-1switch.
brake switch (for auto-
cruise control) malfunc-
tion (short-circuit)
Actuator drive circuit
No.5Repair the harness or reshort-circuit.place the actuator.
Malfunction of the ECU
-Replace the ECU.
-he auto-cruise control system is notDamaged or discon-If the input check codeRepair the harness, or:anceled when the clutch pedal isnetted wiring of clutchNo.23 indicates a mal- repair or replace thedepressed. (vehicles with a manual pedal position switchfunction. No.6-3
clutch pedal position
ransaxle)input circuit switch.
It is canceled, however, when the
)rake pedal is depressed.) Clutch pedal positionswitch improper installa-
tion (won’t switch ON)
Malfunction of the ECU-Replace the ECU.
-he auto-cruise control system is notDamaged or discon-If the input check codeRepair the harness, orzanceled when the shift lever isnetted wiring of park/No.23 indicates a mal- repair or replace thenoved to the “N” position. (vehicles
neutral position switch function. No.6-2park/neutral positionvith an automatic transaxle)input circuit switch.t is canceled, however, when theIrake pedal is depressed.)Improper adjustment of
park/neutral position
switch
Malfunction of the ECU-Replace the ECU.
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AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
13-337
Trouble symptom
Cannot decelerate by using the
SET switch
Probable cause
Check chart No.Remedy
Temporary damagedNo. 2Repair the harness or
or disconnected wir-
replace the SET
ing of SET switchswitch.
Actuator circuit poorNo. 5Repair the harness or
replace the actuator.
Malfunction of the
1 Malfunction of the
ECU
-Replace the ECU.
Cannot accelerate or resume
speed by using the RESUME
switch.
Damaged or discon- No. 3 netted
wiring, or
short-circuit, of
RE-
SUME switch input
circuit Repair the harness or
replace the RESUME
switch.
Actuator circuit poor No. 5iRepair the harness or
; contact replace the actuator.
Malfunction of the
actuator
,
Malfunction of the-Replace the ECU.
ECU
Jute-cruise control system can be i Malfunction of the No. 4
Repair the vehicle-
set while traveling at a vehiclevehicle-speed sensor speed sensor system,
speed of less than 40 km/h (25circuitor replace the part.
nph), or there is no automatic
zancellation at that speed.
Malfunction of the
speedometer cable or
the speedometer
drive gear
Malfunction of the
’ ECU
-Replace the ECU.
The indicator light of the combination Damaged or discon-
neter does not illuminate. netted bulb of
But auto-cruise control system isindicator light
lormal.1
-Repair the harness or
replace the light
bulb.
Harness damaged or
disconnected
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13-340AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
2. CHECKING THE SET SWITCH CIRCUIT
ECU
Description of operation
When the SET switch is switched ON (at the
vehicle speed desired to be maintained, and with
the main switch of the cruise-control switches ON)
that vehicle speed is maintained as a constant
speed.
Furthermore, the constant speed is gradually re- duced
(the “coasting” feature) when the SET switch is pressed and held while the vehicle is
traveling at the previously set constant speed, and,
when the SET switch is released, tne vehicle then
maintains that newly set constant speed (th
e
speed at which the SET switch was
released).
Current flows to the control unit, the cruise control switch (“SET”), and to ground.
Troubleshooting hint
Diagnostic-No.1 5 (automatically cancelled)
ECU terminal voltage
Terminal
No.SignalConditions Terminal voltage
5SET switch
When the SET switch is switched ON ov
When the SET switch is switched OFF
12v
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13-344AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
Description of operation
* -LimA switch
DC motor
7 coil
-
1. When (with the main switch ON) the driver switches ON the SET switch when the pre-
scribed vehicle speed is reached, the control
unit sends current to the electromagnetic clutch
coil of the actuator, thus attracting the clutch plate, and also illuminating the auto-cruise in-
dicator light, Then, when the ring gear of the planetary pinion is secured, the control motor at
the same time causes the DC motor to be
switched ON, and the DC motor operates at high speed.
2.The rotation of the DC motor is, as described in
the illustration above, transmitted to the worm
gear, and thereafter to the worm wheel, the
sun gear, and the planetary pinion in that
sequence. Because the ring gear is secured at
this time, the planetary pinion rotates while revolving around the sun gear. Because the
planetary pinion is installed to the carrier, both
the carrier and the selecotr drive shaft unified
with it, as well as the selector, are caused to rotate.
3.The switching of the direction (PULL or REL.) of
rotation of the selector is accomplished by reversing the direction of current flow to the
motor, and this is automatically regulated by
the control unit.
4. The current flow to the electromagnetic clutch
is interrupted if the driver switches OFF the
main switch, or if the operation of the auto
cruise control system is
cancelled as a result of
the input of a cancel signal to the control unit because the stop light switch, clutch pedal posi-
tion switch (for a manual transaxle) or the park/ neutral position switch (for an automatic trans-
axle) is activated.
5. As a result of the interruption of current to the
electromagnetic clutch, the clutch plate is
caused to return from the electromagnetic
clutch side to the ring gear side by the force of
the spring, and therefore the ring gear be-
comes free.
6. When the ring gear becomes free, the plane-
tary pinion becomes free relative to the sungear, and thus the selector is caused, by the
return spring installed to the selector part, to
return to its original position.
Troubleshooting hint
Diagnostic-No.1 1 (automatically cancelled)
ECU terminal voltage
Terminal
NO.Signal ConditionsTerminal voltage
8Transistor for electro-When the cruise-control switch (main switch) is switch-
magnetic clutch coiled ON o
v
9DC motor drive (“PULL”
During acceleration by RESUME switch
side) 12v
DC motor drive (“REL.”
During speed reduction (coasting) by SET switch
side)ov
20DC motor drive (“PULL” During acceleration by RESUME switch
side) o
v
DC motor drive (“REL.”
During speed reduction (coasting) by SET switch
side) 12v
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AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
13-34
9
8. CHECKING THE CIRCUITS RELATED TO THE OVERDRIVE-CANCELLATION
FUNCTlON

Ignitionswitch
4 A/T
control
module
IO
-I-m
7
E-lWA001
Description of operation
This is a function that cancels the overdrive
function for a certain fixed period of time, if during constant-speed travel in overdrive, the actual vehi-
cle speed decreases to less than the vehicle speed
retained in the memory, and then after a short time
causes the vehicle speed to return to the vehicle
speed retained in the memory.
Overdrive is canceled under the following condi-
tions. 1. If the “RESUME” switch is used.
2. If, during constant-speed travel, the actual vehicle speed decreases to 1.25
km/h (.78
mph) or more below the set vehicle speed. Under either of the conditions described above,
the overdrive-ON signals output from the micro- computer (within the control unit) are no longer
output, and transistor Trl is switched OFF.
As a result, transistor
Tr2 is also switched OFF,
causing the current passing through the overdrive
switch of the selector handle to be interrupted
at transistor
Tr2, with the result that the drive is
controlled at
3rd gear.
Troubleshooting hint ECU terminal voltage Termianl

1
No. :ConditionsTerminal voltage
13) 4AlT control module When the overdrlve
switch IS swrtched
ON 12v
iI14Overdrive switch
When the overdrive switch is switched ON 12v
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13-350AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
TROUBLESHOOTINGMlBEBoa

The auto-cruise control system performs control functions for
the setting or cancellation of the fixed-speed driving speed based upon the data provided by input signals. As a result,
when the auto-cruise control system is canceled by abnormal system operation, the cause of the cancellation is memorizedin a separate circuit by the ECU, thus providing the ECU with
the on-board diagnostic function by certain fixed patterns, as
well as the function of being able to check whether or not the
ECU’s input switches or sensor are normal. Thus, by effectively
using these function, the time required checking and repair can
be shortened.
TROUBLESHOOTING QUICK-REFERENCE CHART
Auto-cruise control system is canceled
when cancellation not wanted. ECU: Electronic control unit
Can the auto-cruise
control system be set
Set the auto-cruise con-
trol system and conduct
a road test.
No (new
normal)
.
Check whether or not, then, the vehicle was driven on a steep
slope.
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AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
NOTE
13-351
Auto-cruise control system cannot be set.
This chart is to be used, then, for troubleshooting if it is not
possible to use the on-board diagnostic for checking.
Prepare to conduct input check.
Where codesNo.21,22, 23, 25 and 26,displayed when,with the vehicle stationary,
the input check codes were recalled?Damaged or disconnected wiring of the ECU power-supply cir-
l Damaged or disconnected wiring of the SET or RESUMEswitch (Go to check chart 2 and 3.)l Damaged or disconnected wiring of the stop light switch,clutch pedal position switch or park/neutral position switch (Go
1 Are the results of all input checks normals?
YesNo
ck the auto-cruise vacuum pump circuit.1 (Go to check chart No.5.)
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Check results
’Probable cause RemedyCheck chartNo.
Code 21 remains even though SETswitch is set to OFF. SET switch ON mal-function
SET switch input line
short-circuitF,I~JI;? the control
Repair the harness.
No. 2
Code 22 remains even though RE-SUME switch is set to OFF. RESUME switch ON
Replace the controlNo.3malfunctionswitch.
RESUME switch inputRepair the harness.line short-circuit
Code 23 is not canceled even if theMalfunction of stopReplace stop lightNo.6
stop light switch is turned OFF by light switch circuit.switch or repair har-
releasing the brake pedal.
ness.
Code 25 does not disappear, and
Malfunction of theCheck or repair theNo.4
code 24 does not appear, evenvehicle-speed sensor vehicle speed sensorthough vehicle speed reaches appro-circuit (damaged or dis-circuit.ximately 40 km/h (25 mph) or higher.connected wiring, orshort-circuit)
Code 26 is not canceled even if the Malfunction of clutch
Replace clutch pedalNo.8clutch pedal position switch is turnedpedal position switchposition switch or repairOFF by releasing the clutch pedal.
circuit.harness.
Code 26 is not canceled even if the
Malfunction of park/Replace park/neutralNo. 7
select lever is moved to anything but neutral position ,switchposition switch or repair
v. P .circuit.harness.
NOTE
If the results of the check of the auto-cruise vacuum pump
circuit (check chart No. 5) and of the auto-cruise vacuum pump
and actuator itself
(P.13-401.) reveal no abnormal condition, re-
place the electronic control unit (ECU).

13-352AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
Trouble symptomProbable causeCheck chart No.
Remedy
l The set vehicle speed varies Malfunction of the ve-No.4Repair the vehicle speegreatly upward or downward.hicle speed sensor cir-l “Hunching” (repeated alternatingsensor system, or re-witplace the part.
acceleration and deceleration) oc- curs after setting is made.
Malfunction of the spee-
dometer cable or spee-
dometer drive gear
Auto-cruise vacuum
No.5Repair the auto-cruisepump circuit poor con-vacuum pump or replactactthe part.
Malfunction of the auto-cruise vacuum pump Malfunction of the ECU
-Replace the ECU.
The auto-cruise control system is not Damaged or discon-If the input check code Repair the harness or rezanceled when the brake pedals is netted wiring of the stopNo.23 indicates a mal-
depressed.light switch input circuit; function. No.6place the stop light
switch.
brake switch (for auto-cruise control) malfunc-
tion (short-circuit)
Auto-cruise vacuum
No.5Repair the harness or repump drive circuit short- place the auto-cruise va
circuit.cuum pump.
Malfunction of the ECU
-Replace the ECU.
The auto-cruise control system is not Damaged or discon-If the input check code
Repair the harness, or:anceled when the clutch pedal is netted wiring of clutchNo.26 indicates a mal-repair or replace thedepressed. (vehicles with a manual
pedal position switchfunction. No.8clutch pedal position
ransaxle)input circuitswitch.
It is canceled, however, when theIrake pedal is depressed.) Clutch pedal position
switch improper installa-
tion (won’t switch ON)
Malfunction of the ECU
-Replace the ECU.
*he auto-cruise control system is not Damaged or discon-If the input check code
Repair the harness, or:anceled when the shift lever is netted
wiring of park/No.26 indicates a mal-repair or replace the
noved to the “N” position. (vehicles neutral position switchfunction. No.7park/neutral position
vith an automatic transaxle)input circuit switch.t is canceled, however, when thebrake pedal is depressed.)
Improper adjustment of
park/neutral position
switch
Malfunction of the ECU-Replace the ECU.
anc$ decelerate by using the SET Temporary damaged orNo.2Repair the harness or re-disconnected wiring of
SET switch input circuitplace the SET switch.
Auto-cruise vacuumNo.5Repair the harness or re-pump circuit poor con-
tactplace the auto-cruise va-
cuum pump and actua-
tor.Malfunction of the auto-cruise vacuum pump
and actuator (including
clogging of negative
pressure passage)
Malfunction of the ECU-Replace the ECU.
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