1987 MAZDA 626 steering

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

1 0 ELECTRICAL COMPONENTS OF ELECTRONICALLY-CONTROLLED POWER STEERING (ECPS)
76G10X-020
76G10X-021
Checking Condition
Condition A
1. Turn the ignition switch OFF.
2. Start the engine and let it idle.
3. Turn the steering wheel to the straight-ahead po-
sition, and check the output pattern.
Refer to page 10—89 for other patterns and indi-
cated failure points.
Condition B
1. Turn the ignition switch OFF.
2. Start the engine and let it idle.
3. Turn the steering wheel 45° left and right from the
center, and check the output pattern.
Refer to page 10—89 for other patterns and indi-
cated failure points.
Condition C
1. Turn the ignition switch OFF.
2. Place the vehicle on a chassis roller tester. Block
the rear wheels, and secure it with chains.
3. Start the engine. Put the transmission in gear and
operate the vehicle at more than 10 km/h (6.2
mph).
4.Check the output pattern.
76G10X-022
Normal pattern
4 4V
Normal pattern Normal pattern
uV
Refer to page 10—90 for other patterns and indi-
cated failure points.
Note
For vehicles equipped with ABS, the ABS
warning light may come on. This is not a fail-
ure. The light will go off when turning the ig-
nition switch OFF and back ON.
86U10X-213
10—88

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
Flow Chart
P/S—1
Failure of solenoid valve or wiring harness (Control unit to Solenoid valve)
Disconnect control unit connector. Check resistance between terminals.
Check voltage between (YL) and D (B) terminal of
control unit connector with engine running
OK
Terminal Resistance
M(LB)—N(LG) 3.5 — 7Q
Check control unit connector, solenoid valve connec-tor, and joint connector for connection, and check output pattern again.
NG
Check the solenoid valve (Refer to page 10—93),
NG
Replace solenoid valve.
P/S-Z Broken wiring harness
(Control unit to Coil)
Terminate of control unit connector with engine running.
NG
Replace control unit.
OK Repair wiring harness (Control unit to Solenoid valve).
Terminal Voltage
L(YL)-D(B) Approx. 12V
NG Repair the wiring harness (Control unit to Ignition
coil).
OK
Replace control unit.
76G10X-025
10—91

1 0 ELECTRICAL COMPONENTS OF ELECTRONICALLY-CONTROLLED POWER STEERING (ECPS)
OK
Check for continuity between each terminals of steer-ing angle sensor and control unit harness side con-nector.
Terminal Continuity Angle sensor Control unit Continuity
(G) KG) Yes
(GY) H(GY) Yes
(GW) J(GW) Yes
Repair wiring harness (Control unit to angle sensor).
OK
Replace control unit.
OK
Replace control unit.
76G10X-043
10—92

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