MAZDA 626 1987 Workshop Manual

ELECTRICAL COMPONENTS OF ELECTRONICALLY-CONTROLLED POWER STEERING (ECPS) 1 0
Broken wiring harness (Fuse box
P/S—5 to Control unit, Control unit or to Body ground)
Measure voltage between terminal of control unit
connector and body ground with ignition ON.
Terminal Voltage UK Replace the control unit.
E(BG) Approx. 12V
D(B) Approx. OV
NG
Replace METER 10A fuse or repair wiring harnesses (Fuse box to Control unit or Control unit to Body ground).
86U10X-218
86U10X-219
Power Steering Solenoid Valve
Inspection
1. Listen for actuation sound of the solenoid valve
when applying 12V between A and B terminals.
2. If no sound is heard, check the resistance of the
solenoid valve with an ohmmeter.
Terminals Resistance
A — B 3.4—6.9 Q
3.
If
there is no continuity, replace the solenoid valve.
Steering Angle Sensor
Inspection
Refer to page 15—16.
Vehicle Speed Sensor
Inspection
Refer to page 15—88.
76G10X-044
10-93

1 0 ELECTRICAL COMPONENTS OF 4-WHEEL STEERING
ELECTRICAL COMPONENTS OF 4-WHEEL STEERING (4WS)
CIRCUIT DIAGRAM
2 UJ I- >-CO -I o CC I-z o o „
0 uoipas)
''R cc ~~w josuas paads oi
=
8<--0 D—S
--0 D-* H 8
--0
D--S
l-S
s-U
0
s g~o 5-s
S--0 D~°
'-HH J
D-c
>-[In
J—0 &-c

1
Note
Refer to page 10—31 for component location.
86U10X-221
10—94

ELECTRICAL COMPONENTS OF 4-WHEEL STEERING 1 0
TROUBLESHOOTING GUIDE
Self-Diagnosis Function
The four-wheel steering (4WS) control unit contains a self-diagnosis function to detect malfunctions
within itself, the 4WS electrical components and circuits.
If a malfunction is detected, the control unit indicates where the problem is located and the 4WS warn-
ing light in the instrument cluster will flash for one minute with a specific pattern,
Troubleshoot the 4WS system according to the following flow chart.
Symptom of problem
76G10X-026
TROUBLESHOOTING
Checking Condition
Condition A
1. Turn the ignition switch OFF.
2. Start the engine after the ignition switch has been
OFF for at least 10 seconds, and check if the 4WS
warning light flashes or illuminates within 60
seconds.
3.
If
flashing or illumination occurs, inspect the circuit.
(Refer to page 10—95.)
76G10X-027
10—95

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

ELECTRICAL COMPONENTS OF 4-WHEEL STEERING 1 0
Warning light output pattern Malfunction Flow chart No.
ON
ncc
Stepper motor or wiring harness 4WS—6 Stepper motor or wiring harness 4WS—6
ON
r\cc
Oil leakage or oil
level switch
4WS—7 Oil leakage or oil
level switch
4WS—7
ON
OFF
Control unit 4WS—8 Control unit 4WS—8
ON
ncc
Control unit, alter-nator, or wiring harness
4WS—9
ON
ncc
Control unit, alter-nator, or wiring harness
4WS—9 Control unit, alter-nator, or wiring harness
4WS—9
86U10X-226
10—97

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
OK
Replace control unit.
Flashes or
Illuminates
Replace rear steering gear assembly.
4WS-3 Failure of solenoid valve or harness
Disconnect R-01 (17-pin) connector. Check voltage between terminals and body ground with ignition switch ON. OK
Terminal Voltage
E(R) Approx. 12V
F(RY) Approx. 12V

J
NG
Disconnect solenoid valve connector. Check for con-
tinuity between terminals on valve side.
Terminals continuity
GR — RY Yes
GY — R Yes
NG
Replace solenoid valve unit.
Replace control unit.
OK Repair harness (Fuse box to Solenoid valve or Sole-noid valve to Control unit).
76G10X-029
10—99

1 0 ELECTRICAL COMPONENTS OF 4-WHEEL STEERING
awq a Failure of stepper motor or harness
Disconnect R-01 (17-pin) connector. Check for no
continuity between each terminal of harness side
connector and body ground.
NG
Disconnect stepper motor connector. Check for no
continuity between each terminal and body ground.
Terminal Continuity
NG
Terminal Continuity
A (WB) No NG WB No
B (WL) No WL No
C (WR) No WR No
D (WY) No WY No
L(G) No G No
OK , OK | NG OK
Repair harness (Step-
per motor to Control
unit).
Replace rear steering
gear assembly.
Check for continuity between terminals of R-01
(17-pin) harness side connector.
NG
Disconnect stepper motor connector. Check for con-tinuity between terminals of motor side connector.
Terminal Continuity NG Terminals Continuity
A (WB) - L (G) Yes NG WB — G Yes
B (WL) — L (G) Yes
NG
WL — G Yes
C (WR) — L (G) Yes
NG
WR — G Yes
D (WY) — L (G) Yes
NG
WY — G Yes
NG
OK OK | NG
Replace control unit. Repair wiring harness (Stepper motor to Con-trol unit).
Replace rear steering gear assembly.
Repair wiring harness (Stepper motor to Con-trol unit).
Replace rear steering gear assembly.
4WS-5 Failure of rear to front steering ra-
tio sensor
Go to 4W5-2
76G10X-046
10-100

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
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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