1987 MAZDA 626 fuse

ELECTRICAL COMPONENTS OF ELECTRONICALLY-CONTROLLED POWER STEERING (ECPS) 1 0

ELECTRICAL
COMPONENTS
OF
ELECTRONICALLY-CONTROLLED POW-
ER STEERING (ECPS)
CIRCUIT DIAGRAM
J POWER STEERING CONTROL SYSTEM (Electronically-Controlled: FE DOHC Engine Without 4WS) AUTO ADJUSTING SUSPENSION CONTROL SYSTEM (AAS)

MAIN FUSE

IcLJ=.cLLJX..=L1.| T'TTTTT'P LB YL GW GY * B «
I-02
Solenoid Valve
[EM] J-04
Check Connector |F|

VG-j-Ijj-LW
J-05
AAS
Conlorl Unit |R| YR YL GR BY B GY WY WR \LL L LuL I 1 L I T. T TTT T T. T,i B G GW LY WL IT TT TI
J-07 Aclualor (FL) |F] WY WR J-08 Aclualor (FR) [D] WY WR J-09 Aclualor (RL) [R| YL YR J-10 Aclualor
(RR) |R|
Yl YR
86U10X-208
Note
Refer to page 10—4 for the component location.
TROUBLESHOOTING GUIDE
The power steering control unit contains a self-diagnosis function to detect malfunctions within itself,
the ECPS electrical components and circuits.
If a malfunction is detected, the control unit indicates where the problem is located by outputting specific
voltage pulsations at terminal wire (YB) of the check connector.
Troubleshooting of the ECPS system, then, is easily performed by comparing the output pattern with
those of the Diagnosis Table on pages 10—89 and 90. 76G10X-019
TROUBLESHOOTING
How To Use Self-Diagnosis System
By using the control unit's self-diagnosis function and
a voltmeter, malfunctions of the system are easily de-
termined. When diagnosing malfunctions, follow the
steps below.
1. Connect a voltmeter to terminal wire (YB) of the
check connector in the engine compartment.
2. Check the output patterns as described on the fol-
lowing page.
86U10X-209
10—87

ELECTRICAL COMPONENTS OF ELECTRONICALLY-CONTROLLED POWER STEERING (ECPS) 1 0
Diagnosis Table
Condition Output pattern Malfunction Flow chart
No.
4.4V
0V-
10 seconds Power steering sole-noid valve or wiring harness (Control unit to Solenoid valve)
P/S—1
Refer to page
10-91
4.4V
0V-
Wiring harness (Con-
trol unit to Ignition coil) P/S—2 Refer to page 10-91
Steering wheel in straight-ahead po-sition with engine idling.
4.4V
OV-
Steering wheel angle sensor or wiring har-ness (Control unit to Angle sensor)
P/S—3 Refer to page 10-92
4.4V
ov-
Normal operation
Wiring harness (Fuse box to Control unit or Control unit to Body ground)
P/S—5 Refer to page 10—93
OV
10 seconds Power steering sole-
noid valve or wiring
harness (Control unit
to Solenoid valve)
P/S—1 Refer to page 10—91
B Steering wheel turned 45° left and right from center with engine idling
4.4V
0V
Wiring harness (Con-
trol unit to Ignition coil)
P/S—2 Refer to page 10-91
4.4V
0V'
Normal operation
4.4V
0V-
Steering wheel angle
sensor or wiring har-
ness (Control unit to
Angle sensor)
P/S—3 Refer to page 10—92
76G10X-023
10-89

1 0 ELECTRICAL COMPONENTS OF ELECTRONICALLY-CONTROLLED POWER STEERING (ECPS)
Condition Output pattern Malfunction Flow chart No.
B Cont'd
OV
Wiring harness (Fuse
box to Control unit or
Control unit to Body
ground)
P/S—5 Refer to page 10-93
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
4.4V —
1 3 s econds Power steering sole-noid valve or wiring harness (Control unit to Solenoid valve)
P/S—1 Refer to page 10-91
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
uv
Power steering sole-noid valve or wiring harness (Control unit to Solenoid valve)
P/S—1 Refer to page 10-91
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
4.4V
n\i
—
Wiring harness (Con-trol unit to Ignition coil) P/S—2 Refer to page 10-91
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
Wiring harness (Con-trol unit to Ignition coil) P/S—2 Refer to page 10-91
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
4.4V
Steering wheel angle sensor or wiring har-ness (Control unit to Angle sensor)
P/S-3 Refer to page 10—92
C
Front wheels driv-en at more than 10 km/h (6.2 mph)

V
Steering wheel angle sensor or wiring har-ness (Control unit to Angle sensor)
P/S-3 Refer to page 10—92
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
4.4V
Vehicle speed sensor or wiring harness
(Control unit to Meter)
P/S—4 Refer to page 10-92
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
uv
Vehicle speed sensor or wiring harness
(Control unit to Meter)
P/S—4 Refer to page 10-92
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
4.4V
OV —
Normal operation —
C
Front wheels driv-en at more than 10 km/h (6.2 mph)
OV
Wiring harness (Fuse box to Control unit or Control unit to Body ground)
P/S—5 Refer to page 10-93
76G10X-024
10-90

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
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
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.

ANTI-LOCK BRAKE SYSTEM (ABS) 1 1
86U11X-1C
Q-08
Q-08
Fail-safe relay
B B BG
(Q-08)(Q-09)

V
BL BR
Motor relay
B BR (Q-09)
LO RY
View from male-pin side
86U11X-167
76G11X-096
ABS WARNING LIGHT
Inspection for No Illumination
1. Check that other warning lights illuminate. If not,
check the METER 10A fuse for burning out.
2. Turn the ignition switch ON.
3. Ground the LY terminal
of
the check connector with
a jumper wire.
4. Check that the ABS warning light illuminates.
If not illuminated, check the bulb and harness (bat-
tery -» check connector).
5. Check for 12V at F (LY) terminal of the control unit
connector.
If the voltage is not as specified, check the harness
(bulb control unit).
If the voltage is as specified, replace the relay box
and the control unit.
RELAY BOX
Inspection of Fail-safe Relay
1. Check for continuity of the relay with an ohmmeter.
Replace the relay box if necessary.
Connecting to BR B (Q-08) B (Q-09) 12V Ground BR B (Q-08) B (Q-09)
— — O— —O
BG BL O— —O
O—O: Indicates continuity
2. Check that the resistance between terminal wire
(BR) and terminal wire (LY) changes when revers-
ing the © and © test-leads. Replace the relay
box if necessary.
Inspection of Motor Relay
1. Check for continuity of the relay with an ohmmeter.
Replace the relay box if necessary.
Connecting to RY B (Q-09) 12V Ground RY B (Q-09)
-—
BR LO o— O
O—O: Indicates continuity
2. Check that the resistance between terminal wire
(BR) and terminal wire (LO) changes when revers-
ing the © and © test-leads. Replace the relay
box if necessary.
WHEEL SPEED SENSOR
Inspection
1. Measure the resistance of the sensor with an
ohmmeter.
Resistance: 800—1,200 0
2. If the resistance is not within specification, replace
the sensor.
3. Check that the harness is not twisted and does not
contact other objects when turning the steering
wheel is turned fully.
11-87