1989 MITSUBISHI GALANT Service Repair Manual

AUTO-CRUISE CONTROL SYSTEM - Troubleshooting13-355
3. CHECKING THE RESUME SWITCH CIRCUIT
Auto-cruisecontrol unit
--f
Y
Cruise-control
switch
Description of operation
The set speed (before cancellation) resumes when the RE- SUME switch is
swrtched ON, even if the constant-speed
control has been cancelled.That speed will not resume, however, even if the RESUMEswitch is switched ON, if the CRUISE switch is switched OFFand if the vehicle speed decreases to 40 km/h (25 mph) orlower.
In addition, when the RESUME is switched ON and held whi!ethe vehicle is traveling at a constant speed, the vehicle speedwill 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.
Troubleshooting hint
Diagnostic-No.1 5 (automatically cancelled)
ECU terminal voltage 13AO382
Terminal
Signal ConditionsTermrnalNo.voltage
18RESUME
When the RESUMEOVswrtchswitch is switchedON.
When the RESUME
Batteryswitch is switchedpositiveOFF.voltaae
4. CHECKING THE VEHICLE-SPEED SENSOR CIRCUIT
Auto-cruisecontrol unit
Combinationmeter
Junction
block
(6)
Description of operation
The vehicle-speed sensor is installed within the speedometer; itsends to the controlunit pulse signals that are proportional tothe rotatron speed (i.e., the vehicle speed) of the transaxle’soutput gear.
This vehicle-speed sensor IS the reed switch type of sensor; itgenerates four pulse signals for each rotation of the speedo-
meter’s driven gear.
Troubleshooting hint
Diagnostic-No.12 (automatically cancelled)
ECU terminal voltage
TerminalSignal Conditions
TerminalNo.voltage
19Vehicle-speedMove the vehicleov-0.7vsensorforward slowly.tFlashingJ3V-higher
13A0381
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13-356AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
5. CHECKING THE AUTO-CRUISE CONTROL VACUUM PUMP Description of operation
Hold modeWhen the SET switch is turned ON by the driver turning theCRUISE switch ON when a determined speed is reached, thecontrol unit receives a set signal, and turns the auto-cruisevacuum pump motor ON. After the constant speed is reached,
the motor, control valve and release valve are repeatedly turned
ON and OFF according to driving conditions.
Ignitionswitch
Auto-cruise
Acceleration mode
When the RESUME switch is pressed, the control unit receives
a RESUME signal and it not only turns the auto-cruise vacuum
pump motor ON but also turns the control valve and release
(10)
control ’ “”unit13AO376
valve ON (valve is closed)
Deceleration mode
When the SET switch is held down, the control unit receives a
set srgnal and it not only turns the auto-cruise vacuum pumpmotor and control valve OFF (valve is opened) but also turns therelease valve ON (valve IS closed).
Release modeWhen the CRUISE switch is turned OFF, the control unit
receives a cancel signal and it not only turns the auto-cruise
vacuum pump motor OFF but also turns the control valve andrelease valve OFF (valve is opened).
Troubleshooting hint
Diagnostic-No.1 1 (automatically cancelled)
ECU terminal voltage
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AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
6. CHECKING THE STOP LIGHT SWITCH CIRCUIT13-357
Stop lrght
Sub fusible link @I
Stop lrght
Auto-cruisecontrol unit 13AQ375
Description of operation
When the brake pedal is depressed during constant-speed
travel, the stop light
swrtch’s (NC) contacts for the cruise-control system open, with the result that the current to the
auto-cruise vacuum pump is interrupted, thus canceling the
constant-speed travel.At the same time, moreover, the closing of the (NO) contacts
for the stop light results in the sending of the cancel signal to
the control unit, so that the auto-cruise vacuum pump current isdiscontinued within the control unit, thereby canceling theconstant-speed travel.
The flow of current is from the sub fusible link @ to fuse No. @Iof the junction block, the stop light switch, and the control unit.
Troubleshooting hint
ECU terminal voltage
TerminalSignal ConditionsTerminalNo.voltage
15Stop light
When the brake Batteryswitch (loadpedal is depressed.positive
side)voltage
When the brakeovpedal is notdepressed.
NOTENC: Indicates ON at all times. (For cruise control)
NO: Indicates OFF at all times. (For stop light)
7. CHECKING THE PARK/NEUTRAL POSITION SWITCH CIRCUIT Description of operation
The park/neutral position switch also functions as the switch
for the starter. If the selector lever is moved to the “N”
pos-ition during constant-speed travel, current flows to the con-trol unit, park/neutral position switch, starter motor, and to
ground; the cancel signal is therefore input to the controlunit, thus canceling the constant-speed travel.
Troubleshooting hint
ECU terminal voltage
(I)
ia
Starter
motor
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13-358AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
8. CHECKING THE CLUTCH PEDAL POSITION SWITCH CIRCUIT
13A0378
Description of operation If the clutch pedal is pressed when driving at a constant
speed, the clutch pedal position 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 pedal position switch junction block from the control
unit and to ground.
Troubleshooting hint
ECU terminal
voltage
Terminal Signal Conditions
TerminalNo.voltage
1Clutch medalWhen the clutchov
Iposition switchpedal is depressed.IWhen the clutch
pedal is not
depressed.Battery
positive
voltage
9. CHECKING THE CIRCUITS RELATED TO THE ACCELERATOR SWITCH OFF FUNCTION
>
Ignition switch
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 duringconstant-speed driving in order not to interfere with the functionof the automatic transaxle.
Troubleshooting hint ECU terminal voltage
TerminalNo.Signal ConditionsTerminalvoltageII3Control unit
At all times Battery
power supply positive
voltage
I gAccelerator
switch
NOTENC: Indicates ON at all time
1 Not rn operation / OFF ) ON 1
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AUTO-CRUISE CONTROL
SYSTEM - Troubleshootina13-359
10. CHECKING THE CIRCUITS RELATED TO THE OVERDRIVE-CANCELLATION FUNCTION\

$;c;tly switch
+ c
Overdriveswrtch
4
Auto-cruiseT-kcontrol unitliIV
I
Cruise-control
(14)
m34,:
4 A/T
control
module
13A0379
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 vehicle 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
cancelled under the following conditions.
If, during constant-speed travel, the actual vehicle speed
decreases to 7 km/h (4.4 mph) or more below the set vehiclespeed.Under either of the conditions described above, the overdrive-ON signals output from the microcomputer (with the controlunit) are no longer output, and transistor Tr, 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 thedrive is controlled at 3rd gear.
Troubleshooting hint ECU terminal voltage
h I
ITerminalSignalIConditions
TerminalNo.voltaoeI
104 A/T controlWhen the overdriveBatterymoduleswitch is switched positiveON.voltage I
11CIIt;riveWhen the overdrive
Batteryswitch is switchedpositiveON.voltage
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13-360AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
11. CHECKING THE THROTTLE POSITION SENSOR AND CLOSED THROTTLE POSITION S\
WITCH
CIRCUIT
(12)
Auto-crursecontrol unit
I 2EB16 I
lntr’
(18)
MFI controlmodule1380424
(12)
models

>
control
unrt
I f
Throttleposrtronsensor
Closed throttle-position swrtch
(18)MFI controlmodule
<1993models

>
13A0425(12)Auto-cruise
control unit
Throttleposition
sensorClosed throttle ‘position
switch
(18)MFI controlmodule13A0428
Description of operation
The throttle position sensor and closed throttle position switchare mounted in the idle speed control motor position sensor Orthrottle body and are sensors in the MFI system. The closed
throttle position switch is turned OFF when the accelerator
pedal is pressed and ON when it is released. In addition, throttle
position sensor output voltage varies according to the degree of
opening of the throttle valve.
Troubleshooting hint

Diagnostic-No.17

Diagnostic-No.1 7
ECU terminal voltage
TerminalNo.
4
5 Signal
Conditions
Terminal
voltage
Closed throttle When accelerator Battery
position switch
-pedal is pressedpositive voltage
When accelerator
pedal is releasedov
ThrottleWhen accelerator 4.0v-5%’position sensorpedal is pressedall the way down
When accelerator 0.48~0.72v
pedal is released
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AUTO-CRUISE CONTROL SYSTEM - Troubleshooting13-361
Wi
thscan tool
With voltmeter
Auto-cruise control
\
Data link
connector
III
n
,
/r-I
/Ground161009
Data link
connector
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On-board diagnostic checking is performed when there has
been an automatic cancellation, without cancel switch opera-
tion.
(1) The following two methods can be used for checking the diagnostic. Note that the data link connector is locatedunder the driver’s side instrument panel.
@ If a scan tool is used
Connect the scan tool’s socket and connector to the
cigarette lighter socket and the data link connector, and
set the tester. Use the tester according to its operation
instructions; display the diagnostic trouble code num-
ber and then check.
@ If a voltmeter is used Connect a voltmeter between the ground terminal and
the terminal for auto-cruise control of the data link con-
nector.
It is possible to discover which circuit is the cause of
the cancellation by verifying the indication shown by
the voltmeter with the display patterns shown on the
next page.
(2) When the diagnostic trouble code No. is displayed, check by referring to the check chart applicable to that number.
NOTE
Canceling the diagnostic trouble codes
The diagnostic trouble codes remain in memory until the battery is turned off but they can be canceled in the follo-
wing ways without disconnecting the battery terminals.
@ By turning on the ignition switch.
@ By turning the main switch ON while the SET switch is ON and then, within 1 second, turning the RESUME
switch ON. (Put into condition for input check recep-
tion).
@ By turning ON the SET switch and stop light switch at the same time and continuing the ON condition for 5
seconds or more.
@I By checking that the diagnostic trouble codes are canceled using a scan tool or voltmeter.

13-362AUTO-CRUISE CONTROL SYSTEM - Troubleshooting
DIAGNOSTIC DISPLAY PATTERNS AND TROUBLE CODES Code Display patterns (output codes)
No.(use with voltmeter)
11
xJa-.tu
Probable causeCheck chart No.
Abnormal condition of actuator drive systemNo.5
Abnormal condition of auto-cruise vacuum
pump drive system
1212vAbnormal condition of vehicle-speed signal No. 4systemov/
13"12vLow-speed limiter activation (The system is -normal if it can be reset.)
ov
14*12v14Automatic cancellation activated by vehicle -speed reduction. (The system is normal if it
ov can be reset.)
15"12v15Control switch malfunction (when SET and No.2, 3
RESUME switches switched ON simul-
ovtaneously)
16"Cancel switch ON signal input (including inputNo. 6-1, 6-2. 6-3
12v16wirings damage or disconnection, or problemin circuitry within the control unit) ov
we>
Abnormal condition of auto-cruise control unit-
17"12v17Throttle position sensor malfunctionNo. 11
Closed throttle position switch malfunction
ov
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 ther\
e 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 c\
heck according to each individual check chart that is applicable.
ON
OFF
-
Display when vehicle speed is less thanapproximately 20 km/h (12 mph), or before
the auto-cruise control system is set
0.5 set
++P5 setDiagnostic trouble codes are displayed when, after cancel-
lation of the auto-cruise control system, the vehicle speed
decreases to less than approximately 20 km/h (12 mph),
and are canceled by turning OFF the battery or canceling
the diagnostic trouble codes. (Refer to
P.13-361.) cuume type> 03ROlS6
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2.Diagnostic trouble codes are displayed when, after cancel-
lation of the auto-cruise control system, the vehicle speed
decreases to less than approximately 20 km/h (12 mph),
and are erased by switching OFF the ignition switch or the
main switch.