check engine MAZDA 626 1987 Workshop Manual

1 0 ELECTRICAL COMPONENTS OF 4-WHEEL STEERING
Condition B
1. Place the vehicle on a chassis roller tester. Block
the rear wheels, and secure it with chains.
2. Turn the ignition switch OFF.
3. Start the engine after the ignition switch has been
OFF for at least 10 seconds. Put the transmission
in gear and operate the vehicle at more than 40
km/h (25 mph).
4. Check if the 4WS warning light flashes or il-
luminates within 60 seconds.
5.
If
flashing or illumination occurs, inspect the circuit
by referring to the table below.
76G10X045
Diagnosis Output Pattern
Warning light output pattern
0.5 sec —i 2.5 sec
Malfunction
Normal operation, control unit or wir-ing harness
Speed sensors or
wiring harness
Flow chart
No.
4WS—0
4WS—1
Rear steering gear
assembly
Solenoid valve or wiring harness
Stepper motor or wiring harness
Rear-to-front steer-ing ratio sensor or wiring harness
4WS—2
4WS—3
4WS—4
4WS—5
86U10X-225
10-96

1 0 ELECTRICAL COMPONENTS OF 4-WHEEL STEERING
4WS-0 Normal operation or failure of con-trol unit or harness
Start engine.
Disconnect R-01 (7-pin) connector. Check that 4WS warning light flashes or illuminates.
NG
Repair harness. (Fuse box to Control unit or Control unit to Body ground).
YES No electrical problem.
NO
Reconnect connector.
Check voltage between terminals and body ground.
Terminal Voltage
G(B) OV
H(B) OV
K(G) Approx. 12V
L(G) Approx. 12V
N(B) OV
OK Replace control unit.
4WS-1 Failure of speed sensors or wiring
harness
Check speed sensor at transaxle. (Referring to page 10—103)
OK
NG Replace speed sensor.
Check for continuity between terminal of transaxle speed sensor and R (O) terminal of the control unit connector.
NG^ Repair wiring harness (Control unit to Transaxle
speed sensor).
Cont'd 76G10X-028
10—98

ELECTRICAL COMPONENTS OF 4-WHEEL STEERING 1 0
4WS-6 Failure of rear to front steering ra-tio sensor or harness
Start engine.
I
Check voltage between control unit terminal and body ground.
OK
Check voltage between control unit terminal and body ground.
Terminal Resistance
2F (GO) Approx. 5.0 V
NG Replace control unit.
Terminal Resistance
2G (GW) Approx. 4.5 V
OK Replace control unit.
NG
Check rear to front ratio sensor (Refer to page 10-103).
NG Replace rear steering gear assembly
OK
Repair harness (Control unit to Sensor).
Flashes or illuminates
Check voltage between 0(Y) terminal of R-01 (17-pin)
connector and a body ground.
Terminal Voltage
0(Y) 0 V
OK Replace control unit.
NG
10-101

1 0 ELECTRICAL COMPONENTS OF 4-WHEEL STEERING
flashes
Replace control unit
4WS-9 Failure of control unit, alternator, or wiring harness
Start engine,
I
Check voltage between terminal of control unit con-nector and body ground.
Terminal Voltage
G(B) OV
H (B) OV
K(G) Approx. 12V
L (G) Approx. 12V
N(B) OV
OK
NG
Check 4WS relay and timer (Refer to page 10—103) -
OK
Check battery, harness, and alternator.
NG
Turn ignition switch OFF. Start engine. Check if 4WS warning light flashes or illuminates.
NO
Momentary problem (If warning light often flashes or illuminates, check battery and alter-nator. Replace control unit if necessary).
YES
Replace control unit.
Replace relay and timer
76G10X-031
4WS WARNING LIGHT
1. Turn the ignition switch OFF.
2. Turn the ignition switch ON, and check that the
4WS warning light illuminates.
3. If there is no illumination, check the warning light
bulb and wiring harness.
Replace the control unit if necessary.
86U10X-232
10-102

ELECTRICAL COMPONENTS OF 4-WHEEL STEERING 1 0
SPEED SENSOR (IN METER)
1. Jack up the front of the vehicle.
2. Connect a voltmeter between 2A (GR) terminal of
the control unit connector and a body ground.
3. Start the engine. Check that periodic voltage is de-
tected when turning'the front wheels slowly.
4. If periodic voltage is not detected, check the wir-
ing harness. Replace the speed sensor if
necessary.
86U10X-233
SPEED SENSOR (AT TRANSAXLE)
1. Jack up the front of the vehicle.
2. Connect a voltmeter between R (O) terminal of the
control unit connector and a body ground.
3. Start the engine. Check that periodic voltage is de-
tected when turning the front wheels slowly.
4. If periodic voltage is not detected, check the wir-
ing harness. Replace the speed sensor if
necessary.
86U10X-234
REAR-TO-FRONT STEERING RATIO SENSOR
Check the resistance between the terminals with an
ohmmeter.
Terminal [ Resistance
GB—GO l 3.5—6.5 kfi
GB—GW ' 3.2—5.9 kfi

If
the resistance is not within specification, replace the
rear steering gear assembly.
86U10X-235
OIL LEVEL SWITCH (IN P/S RESERVOIR)
Check for continuity of the switch with an ohmmeter.
Fluid level Continuity
More than L No
Less than L Yes

If
the continuity is not within specification, replace the
P/S reservoir.
86U10X-236
10—103

1 0 ELECTRICAL COMPONENTS OF 4-WHEEL STEERING
86U10X-237
76G10X-047
10—104
RELAY AND TIMER
1. Start the engine.
2. Check voltage between each terminal of the relay
and timer connector and a body ground.
Terminal Voltage
a 12V
b 12V
d 12V
i 12V
1 OV
If the voltage is not as specified, replace the fuse
or repair the harness.
3. Check voltage between each terminal and a body
ground with the engine running.
Terminal Voltage
f 12V
h 12V
4. Check that the voltage of f and h terminal is 12V
for approximately 7 to 10 seconds after the igni-
tion switch is turned OFF.
If not, replace the relay and timer.

POWER BRAKE UNIT 1 1
86U11X-038
0
o
X
\ V^ Third
Second
^ First
86U11X-039
O X

fiSy

V
86U11X-040
Pedal-depression Pre!tur!9au9e
force gauge
^Intake manifold
86U11X-041
POWER BRAKE UNIT
FUNCTION CHECK
Simple Method
First step
1. With the engine stopped, depress the pedal a few
times.
2. With the pedal depressed, start the engine
3. If immediately after the engine starts the pedal
moves down slightly, the unit is operating.
Second step
1. Start the engine.
2. Stop the engine after it has run for
1
or 2 minutes.
3. Depress the pedal with the usual force.
4.
If
the first pedal stroke is long and becomes short-
er with subsequent strokes, the unit is operating.
5. If a problem is found, inspect for damage of the
check valve or vacuum hose, and examine the in-
stallation condition. Repair if necessary, and inspect
it once again.
Third step
1. Start the engine.
2. Depress the pedal with the usual force.
3. Stop the engine with the pedal still depressed.
4. Hold the pedal down for about 30 seconds.
5. If the pedal height does not change, the unit is
operating.
6. If there is a problem, check for damage to the
check valve or vacuum hose, and check the con-
nection. Repair if necessary, and check once
again.
If the nature of the problem is still not clear after fol-
lowing the 3 steps above, follow the more detailed
check described in "Method using tester".
Method Using Tester
Connect a pressure gauge, vacuum gauge, and ped-
al depression force gauge as shown in the figure. Af-
ter bleeding the air from the pressure gauge, conduct
the test as described in the 3 steps below.
Note
Use commercially available gauges and ped-
al depression force gauge.
11—27

1 1 POWER BRAKE UNIT
a) Checking for vacuum loss
Unloaded condition
1. Start the engine.
2. Stop the engine when the vacuum gauge reading
reaches 500 mmHg (19.7 inHg).
3. Observe the vacuum gauge for 15 seconds.
If
the
gauge shows 475—500 mmHg (18.7—19.7
inHg), the unit is operating.
76G11X-065
Loaded condition
1. Start the engine.
2. Depress the brake pedal with a force of 196 N (20
kg, 44 lb).
3. With the brake pedal depressed, stop the engine
when the vacuum gauge reading reaches 500
mmHg (19.7 inHg).
4. Observe the vacuum gauge for 15 seconds.
If
the
gauge shows 475—500 mmHg (18.7—19.7
inHg), the unit is operating.
76G11X066
b) Checking for hydraulic pressure
1. If with the engine stopped (when vacuum is 0
mmHg) the relation between pedal force and fluid
pressure is within specification, the unit is operating.
Pedal force Fluid pressure
196 N (20 kg, 44 lb) | 1,177 kPa (12 kg/cm2, 171 psi) mia
76G11X-067
2. Start the engine. Depress the brake pedal when
the vacuum reaches 500 mmHg (19.7 inHg).
If the relation between pedal force and fluid pres-
sure is within specification, the unit is operating.
Pedal force Fluid pressure
196 N (20 kg, 44 lb) 7,063 kPa (72 kg/cm2, 1,024 psi) min.
76G11X068
11-28

POWER BRAKE UNIT 1 1
76G11X-034
INSPECTION OF CHECK VALVE
Note (MTX)
The check valve is pressed into the vacuum
hose. There is an arrow on the hose surface
to indicate direction of installation.
Inspection
1. Disconnect the vacuum hose from the engine.
2. Apply suction and pressure to the hose from the
engine side. Check that air flows only toward the
engine.
If the air passes in both directions or not at all, re-
place the check valve (along with the hose).
REMOVAL
Remove in the sequence shown in the figure, referring to removal note for specially marked parts.
1. Fluid level sensor connector
2. Vacuum switch coupler
(RF, RF-CX)
3. Brake pipe
4. Master cylinder
5. Clutch pipe holder
6. Vacuum hose and check
valve
7. Clevis pin
8. Steering shaft
76G11X-069
9. Power brake unit
10. Gasket
11. Locknut
12. Operating lever
11-29

VACUUM PUMP 1 1
VACUUM PUMP
1. Disconnect the vacuum hose and release the re-
maining vacuum.
2. Connect a vacuum gauge as shown in the figure.
3. Run the engine at idle speed.
Idle speed: 720 1 20 rpm
4. Check that the vacuum reaches 500 mmHg (19.7
inHg) in 8 seconds or less.
5. Check that the maximum vacuum is within approx.
700—720 mmHg (27.6—28.3 inHg) in 80 sec-
onds or less.
REMOVAL AND INSTALLATION
1. Remove in the sequence shown in the figure.
2. Install in the reverse order of removal, referring to installation note for specially marked parts.
Note
The engine oil will leak out when disconnecting the oil hose. Prepare a suitable container
for it to drain into.
76G11X-038
76G11X-037
1. Vacuum hose
2. Oil return hose
3. Oil inlet hose
4. Drive velt cover
5. Vacuum pump