1987 SUZUKI GRAND VITARA Service Repair Manual

4) Using couplers of the same shape as that
mentioned in step 3) or 1P couplers, connect
only mixture control solenoid valve wire
terminals (Yellow/Black terminal of coupler
@ and Black/White terminal of coupler 0,
White terminal of coupler @ and Blue/Red
terminal of coupler 0.
NOTE:
l Couplers must be used to connect each
terminal.
l Use special care when connecting terminals
as wrong connection may cause damage to
other parts.
9
1. Coupler of MCSV side7. 1 p coupler2. Coupler of wire harness side8. 5p coupler (when using this3. Yellow/Black wire terminalcoupler, leave positions
4. Black/White wire terminalindicated as 9 in figure
,5. White wire terminalblank).
6. Blue/Red wire terminal9. Blank
Fig. 5-3-27
5) Remove cap of duty check coupler located
on dash panel and connect terminals with a
lead wire to short them.
6) Turn ignition switch “ON” and “OFF”
repeatedly (without starting engine) and
check if MCSV. operating sound is heard as
ignition switch is operated.
Operating sounds prove its proper operation.
Fig. 5-3-29
7) Upon completion of checks, re-connect
disconnected couplers to original positions
securely.
Checking thermal switch
NOTE:
For the rough check of the operation, thermal
switch can be checked by warming up (above
46.5”C, 116°F) or cooling down (below 3O”C,
86°F) the engine without being removed from
the intake manifold.
The check procedure is the same as the follow-
ing except item 11, 21, 5) and 6).
1) Drain cooling system.
2) Remove thermal switch from intake mani-
fold.
3) Cool switch to below 30°C (86” F), and using
an ohmmeter, check that there is continuity
between terminals.
Fig. 5-3-28
1. Duty check coupler2. Lead wire
5-26

1
1. Thermal switch
2. Cool water
3. Thermometer
1. Thermal engine room switch
Fig. 5-3-30 Checking thermal switch in coolFig. 5-3-32 Checking thermal engine room
waterswitch
4) Heat switch to above 46.5”C (116”F), and
check that there is no continuity between
terminals.t
Ll
%I
Rio 0II
I \\1. Hot waterII/2. Heater
Fig. 5-3-31 Checking switch in hot water
5) Reinstall switch to intake manifold. Before
installing, wind sealing tape on its thread.
6) Refill cooling system.
Checking thermal engine room switch
1) Disconnect connector of switch and connect
ohmmeter between terminals on switch side.
2) Make sure that switch is “ON” (ohmmeter
indicates “Zero”ohm) when atmospheric
temperature is below 7°C (44” F) and “OFF”
(ohmmeter. indicates infinity) when above
19.5”C (67” F).
Checking high altitude compensator
Check the compensator as follows:
1) Disconnect the coupler of compensator and
connect an ohmmeter to the compensator.
2) Check to be sure that;
* If the altitude of the place where this check is
performed is above 1,220 m (4,000 ft), the
ohmmetershould indicate“Zero” ohm
(compensator is ON).
0 If the altitude is below 1,220 m (4,000 ft),
the ohmmeter should indicate infinity ohm
(compensator is OFF).
3) After checking, connect the coupler.
1. High altitude compensator
Fig. 5-3-33 Checking high altitude compensator
5-27

Checking oxygen sensor
1) Warm up the engine to normal operating
temperature.
2) Disconnect the connector of the oxygen
sensor.
Fig. 5-3-34 Connector of oxygen sensor
3) Connect the voltmeter between the oxygen
sensor side terminal of the disconnected
connector and the ground as shown in below
figure.
NOTE:
Be sure to use a voltmeter whose inner resis-
tance is more than some MS!Z per IV or a
digital type voltmeter. Any other voltmeter
should not be used because accurate measure-
ments are not obtained.
NEVER apply voltage to the oxygen sensor as
it may cause damage to the sensor.
NEVER connect ohmmeter to the oxygen
sensor as it may cause damage to the sensor.
i
1. Oxygen sertsor side terminal
2. Ground
3. Left side fender
4) While keeping the engine running at 1,500 -
2,000 rpm, turn the wide open micro switch
“OFF” by moving the lever with the finger as
shown in below figure. Then take the reading
of the voltmeter to make sure it is about 0.8V.
I, Lever
2. Wide open micro switch
Fig. 5-3-36 Moving lever3. Carburetor
5) With the engine running at 1,000 - 1,500
rpm, disconnect the vacuum hose at the in-
take manifold as shown in below figure. At
this time, check to ensure that the voltmeter
indicator is below 0.2V.
1. Vacuum hose
2. Intake manifold3. MCV
Fig. 5-3-37 Disconnecting vacuum hose
6) After checking, reconnect the vacuum hose to
the intake manifold and the connector of
oxygen sensor.
Fig. 5-3-35 Connec ring voltmeter
5-28

Checking feed back system circuits
When the feed back system does not seem to operate properly even after each of its components has been
checked and proved normal, it is necessary to check each circuit of the feed back system. The checking
procedure of each circuit is described here.
[Checking ECM ground circuits]
The ECM is grounded both at the dash panel and
the intake manifold. If either grounding is not
made securely, the feed back system will not
operate. Therefore, check if the ECM is properly
grounded at these two points according to the
following procedure.
1) Turn OFF the ignition switch.
2) Disconnect the coupler from the ECM.
3) Connect an ohmmeter between the terminal
@ of the disconnected coupler (on the
wiring harness side) and the body (ground)
as shown in below figure, and measure the
resistance. Then repeat the same with the
terminal 0.1. ECM (Electronic Control2. CouplerModule)3. Instrument main panel
Fig. 5-3-38 ECM and coupler
1. Coupler (Viewed from wire harness side)
2. “B” (Black) leed wire
3. “B/G” (Black/Green) lead wire
4. Body ground
5. Engine ground
Fig. 5-3-39Checking ECM ground circuit
5-29

4) If the measured resistance between each terminal ( @ and @ 1 and the body is “ZERO (0)” ohm, the
ECM is grounded securely at two points. If the resistance is not “ZERO (0)” ohm, the possibility is
that the lead wire between the terminal (0 or @ ) and the ground is not securely grounded or
disconnected.
The below figures show the particular points where “B” and “B/G” wires are grounded. Check for
their secure grounding by referring to these figures.
1. Body ground3. Dash panel2. Black/Green lead wire 4. Battery
Fig. 5-3-40 Body ground
1. Engine ground3.Thermostatcap
2. Black lead wire4.Intake manifold
Fig.5-3-41Engine ground
5) After checking, connect the coupler to ECM securely.
5-30

[Checking ECM power circuits]
Connected to the ECM are the ignition coil and solenoids or solenoid valves. If a disconnection or a
failure of contact occurs within a circuit (power circuit) including any of these coil or solenoids or sole-
noid valves, signals will not be sent to the ECM and as a result, the feed back system will not operate
properly. Therefore, check the power circuits according to the following procedure.
1) Disconnect the coupler connected to the ECM.
2) Turn ON the ignition switch but be sure not to run the engine.
3) Connect a voltmeter between the terminal @ of the disconnected coupler (on the wiring harness side)
and the body (ground) as shown in below figure and measure the voltage. And then repeat the same
with each of the terminals 0, 0, 0, 0, 8, @ and 0. If the measured voltage between each
terminal and the body is about 12V, each circuit is in good condition.
4) If about 12V is not obtained in the above check, the particular circuit may be disconnected or out of
contact. Check the circuit for such conditions.
5) After checking, connect the coupler to ECM securely..
1. Coupler (Viewed from wire harness side)10. Three way solenoid valve (EGR system)
2. Battery11. Br (Brown) lead wire
3. Ignition switch (ON)!2. BI/R (Blue/Red) lead wire
4. Ignition coil13. B/W (Black/White) lead wire
5. Vacuum switching valve14. Br/W (Brown/White) lead wire(secondary throttle valve)15. BI/B (Blue/Black) lead wire6. Three way solenoid valve (Idle-up)16. BI/Y (Blue/Yellow) lead wire7. Mixture control solenoid17. BI/W (Blue/White) lead wire8. Switch vent solenoid18. BllG (Blue/Green) lead wire9. Fuel cut solenoid valve
Fig. 5-3-42 Checking ECM power circuits

[Checking sensors and their lead wires]
The sensors constituting the feed back system are; wide open micro switch, idle micro switch, thermal
switch, high altitude compensator, thermal engine room switch and fifth switch. If any of the above
sensors malfunctions or if the sensor circuit has some trouble, signals are not sent to the ECM and conse-
quently the feed back system will not function properly.
Therefore, check each sensor and its circuit according to the following procedure.
1) Turn OFF the ignition switch.
2) Disconnect the coupler from the ECM.
3) Connect the ohmmeter between the terminal @ of the disconnected coupler and the terminal @
(ground) as shown in below figure and measure the resistance. And then repeat the same with each of
the terminals 0, @I, @I, @ and @I.
1. Coupler (Viewed from wireharness side)
2. Wide open micro switch3. idle micro switch
4. Thermal switch
5. Thermal engine room switch6. Fifth switch
7. High altitude compensator
8. Gr/R (Gray/Red) lead wire9. Gr/Y (Gray/Yellow) lead wire10. 81 (Blue) lead wire
11. P/B (Pink/Black) lead wire
12. Gr/B (Gray/Black) lead wire
13. Lg/R (Light green/Red) lead wire
14. B/G (Black/Green) lead wire
Fig. 5-3-43 Checking sensors and their circuits
4) If each ohmmeter reading is as given below, the sensor and its circuit are in good condition. But if not,
the sensor itself may be defective or the lead wire disconnected or out of contact. After checking,
connect the coupler to ECM securely.
Idle micro switch
High altitude compensator
Thermal engine room switch
Wide open micro switch
1 Fifth switch

Ohmmeter
Terminal reading (S2)Condition
When coolant temp. is low.
When coolant temp. is above 46.5’C (I 16’F).
0 1
When engine is warm and accelerator pedal is not depressed.
When accelerator pedal is depressed a little.
00
@
When altitude is below 1,220 m (4,000 ft.).
0When altitude is above 1,220 m (4,000 ft.).
0
When temp. in engine room is low.
When temp. in engine room is above 19.5’C (67°F).
0When accelerator pedal is not depressed or depressed only a
0little.
CoWhen accelerator pedal is depressed all the way.
@ Oa
When gear shift lever is shifted to low, second, third, forth or
reverse gear position.
0When gear shift lever is shifted to fifth gear position.
5-32

[Checking function of oxygen sensor and feed back system1
If oxygen sensor fails to send signal to the ECM, the feed back system does not operate. While the feed
back system is at work, the ECM sends out the feed back signal, and in this condition, after warming up
engine to normal operating temperature, when the cancel switch or check switch, is turned ON, the “CHECK
ENGINE” light in the instrument cluster flashes. If the “CHECK ENGINE” light does not flash in such
conditions as described above, check the feed back system for function according to the following pro-
cedure.
NOTE:
Except for Canadian specification vehicle, also when mileage sensor is turned ON (the odometer indicates
50,000, 80,000 or 100,000 miles), the “CHECK ENGINE” light flashes. If the “CHECK ENGINE” light
does not flash in such condition, check the feed back system for function according to the following
procedure.
1) Remove the ECM from the instrument main panel.
2) Connect the coupler to the ECM..
(Don’t disconnect the coupler from the ECM if connected)
3) Warm up the engine to the normal operating temperature and keep it at idle.
4) Connect voltmeter between the terminals @I (oxygen sensor signal) and @ (ground) as shown in below
figure.
5) If the voltmeter indicator deflects between OV and 0.8V while racing the engine at a speed between
idling and 1,500 - 2,000 rpm, the feed back system is in good condition.
Fig,
NOTE:
Never connect ohmmeter as it may
cause damage to the oxygen sensor.
U.S.A. specification vehicle
1.ECM2. Coupler (Connected to ECM)
3.Oxygen sensor
4.Sealed wire5. W (White) lead wire
6. I3 (Black) lead wire7. Br/B (Brown/Black) lead wire8.Cancel switch9.“CHECK ENGINE” light
10. Ignition switch (ON)11.Battery
12.Mileage sensor115 'L----JA Canadian specification vehicle
I 5-3-44 Checking oxygen sensor signal
13. Check switch
6) If the indicator does not deflect between OV and 0.8V, possible causes are as follows.
Voltmeter indicator:
Remains at “Zero (0)“V
Possible causes
0 Oxygen sensor lead wire is disconnected or out of contact.
0intake system is leaky or air/fuel mixture is too lean due to malfunction
of carburetor,
0Inner resistance of voltmeter is too small.
0 Oxygen sensor is defective.
Indicates about 0.8V and does not
deflect.
0Choke is operating because engine is not warmed up fully.
0 Thermal switch is defective.
0 Wide open micro switch is defective.
0Lead wire of mixture control solenoid is disconnected.
0 Mixture control solenoid valve is defective.
5-33