MITSUBISHI GALANT 1989 Service Repair Manual

13-334AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
TROUBLESHOOTIN
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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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13-338AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
Trouble symptomProbable causeCheck chart No.Remedy
Malfunction of control function by
Malfunction of circuitNo. 7Repair the harness or
ON/OFF switching of ELC 4
A/Trelated to acceleratorreplace the part.
accelerator switch switch OFF function
(Non-operation of torque converterclutch, 2nd gear hold, etc.)
Malfunction of the
ECU
Overdrive is not canceled during
fixed speed driving.
Malfunction of circuitNo. 8Repair the harness or
related to overdrive
replace the part.
cancelation, or mal-
function of ECU
No shift to overdrive during man-
ual driving.
.
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