TOYOTA PRIUS 2001 Service Repair Manual

± DIAGNOSTICSBODY CONTROL SYSTEM
DI±691
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check ECU±B, DC/DC, GAUGE and DOOR fuse.
CHECK:
Check continuity of ECU±B, DC/DC, GAUGE and DOOR fuse.
OK:
Continuity
NG Replace the failure fuse.
OK
2 Check voltage between terminals B, BDR and E of body ECU connector.
PREPARATION:
(a) Turn ignition switch OFF.
(b) Disconnect the Body ECU connector.
CHECK:
Measure voltage between terminals B, BDR and E.
OK:
Voltage: 10 ± 14V
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±683).
NG
3 Check wireharness and connector between body ECU and body ground (See
page IN±41).
NG Repair or replace wireharness or connector.
OK
Check and repair wireharness and connector
between Body ECU and battery.

I15489
Body ECU
B B9
B8
1 5
8 11
159
8
8
2
13 5 3 1
6
24
1 1BDR F
FJ27
J/C
W±B
W±B
B±GB±Y
W±G W±GWR±G
2C
2D
2K 2B2H
2D10A GAUGE IG1 Relay30A DOOR7.5A ECU±B
5A AM1
J11
J/C
ID Battery F13 F11100A DC/DC FL Block No. 1I15 Ignition Switch
AM1 IG1
F18
FL Block No. 2
120A MAINB9 E Instrument Panel J/B
B
IG
A 7.5A OBDII
9
2DR±G
D
D
J26
J/CW±L W±L
W DI±692
± DIAGNOSTICSBODY CONTROL SYSTEM
2001 PRIUS (RM778U)
Ignition Switch Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned to the ACC position, battery voltage is applied to the terminal ACC of the
ECU and when the ignition switch is turned to the ON position, battery voltage is applied to the terminal IG
of the ECU.
WIRING DIAGRAM
DI7NO±01

± DIAGNOSTICSBODY CONTROL SYSTEM
DI±693
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check AM1 fuse.
CHECK:
Check continuity of AM1 fuse.
OK:
Continuity
NG Replace the failure fuse.
OK
2 Check voltage between terminals 8, 15 and E of body ECU connector.
PREPARATION:
Turn ignition switch ON.
CHECK:
Measure voltage between terminals 8, 15 and E.
OK:
Voltage: 10 ± 14V
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±683).
NG
3 Check wireharness and connector between body ECU and body ground (See
page IN±41).
NG Repair or replace wireharness or connector.
OK
Check and repair wireharness and connector
between body ECU and battery.

I15486
OFF
TAIL
HEAD
LOWTHELB9
BODY ECU
Light
Control
SW
Dimmer
SWHIGH
FLASHH 17 LG±R ID2
135
W±B A J17
J/C
IG16 C13
Combination SWT 18
R 6
ID2
R LG±R
14
HF HU HL DI±694
± DIAGNOSTICSBODY CONTROL SYSTEM
2001 PRIUS (RM778U)
Light Control Switch Circuit
CIRCUIT DESCRIPTION
This circuit defects the state of the light control switch.
WIRING DIAGRAM
DI5VO±07

± DIAGNOSTICSBODY CONTROL SYSTEM
DI±695
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check light control switch (See page DI±689).
NG Replace the headlight control switch.
OK
2 Check wireharness and connector between headlight control switch and body
ECU (See page IN±41).
NG Repair or replace wireharness or connector.
OK
Proceed to next circuit inspection shown on
problem symptoms table (See page
DI±683).

I15485
BatteryB9
BODY ECU
11
F112 5
6 3
2 15
1
11
1 WID2 2F
2K 2HTAIL
RELAY7.5A
TAIL Instrument Panel J/Bto Taillight
F18
FL BLock No. 2 FL Block No. 1LG LG
F13B±GTRLY
100A DC/DC 120A MAIN DI±696
± DIAGNOSTICSBODY CONTROL SYSTEM
2001 PRIUS (RM778U)
Taillight Relay Circuit
CIRCUIT DESCRIPTION
Taillight relay will be ºONº by operating the taillight switch. The transistor which activates the tail light relay
has two sorts: one activates by the tail light switch for fail safe and the other activates by CPU.
When the theft deterrent system is activated, it causes the transistor in the ECU to switch ON and OFF at
approximately 0.4 sec. intervals. This switches the taillight control relay ON and OFF, thus flashing the tail-
lights (See the wiring diagram below).
In this condition, if any of the following operations is done, the transistor in the ECU goes OFF and the taillight
control relay switches OFF, thus stopping the taillights flashing:
(1) Unlock the front LH or RH door with a key.
(2) Turn the ignition switch to ACC or ON position.
(3) Unlock the doors with the wireless door lock control system.
(4) Wait for approximately 60 seconds.
WIRING DIAGRAM
DI6QY±04

± DIAGNOSTICSBODY CONTROL SYSTEM
DI±697
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check taillight relay (See page DI±691).
NG Replace the taillight relay.
OK
2 Check wireharness and connector between taillight relay and body ECU, battery
and taillight relay (See page IN±41).
NG Repair or replace wireharness or connector.
OK
Proceed to next circuit inspection shown on
problem symptoms table (See page
DI±683).

I15484
2 3 66
8 7
1 4 2
1
4
3 2 1 1
11
1
710
883
A L D
FE
E
E
LE
ER±L
R±G
R±W
R±G R±W R±W R±W
R±G
R±G B±G
R±G B
F13 F12
2I
2A 1B1F
1F
1F3
ID2 IA2J20
J/C
IA1
J4J5
ID 2K 2A
15
17
BatteryC10 High Beam
Indicator Light
(Comb. meter) F18
FL Block No. 2
J11
J/CJ4 H2
Headlight RH
10A HEAD (LH) 10A HEAD (RH)
Short Pin HEAD RelayEngine Room J/BB9
Body ECU
Short Pin
120A MAIN
Instrument
Panel J/BJ12 J13
W±B
H1
Headlight
LH
1
FL Block No. 13
1
HRLY
Instrument
Panel J/B DI±698
± DIAGNOSTICSBODY CONTROL SYSTEM
2001 PRIUS (RM778U)
Headlight Relay Circuit
CIRCUIT DESCRIPTION
Head light relay will be ºONº by operating the headlight switch. The transistor which activates the headlight
relay has two sorts: one activates directly by the headlight switch for fail safe and the other activates by CPU.
the one that activates by CPU has two systems and prevents the headlight from turning off at the time of
one system trouble in the automatic operation circuit.
When the theft deterrent system is activated, it causes the transistor in the ECU to switch ON and OFF at
approximately 0.25 sec. intervals. This switches the headlight control relay ON and OFF, thus flashing the
headlights (See the wiring diagram below).
In this condition, if any of the following operations is done, the transistor in the ECU goes OFF and the head-
light control relay switches OFF, thus stopping the headlights flashing:
(1) Unlock the front LH or RH door with a key.
(2) Turn the ignition switch to ACC or ON position.
(3) Unlock the doors with the wireless door lock control system.
(4) Wait for approximately 60 seconds.
WIRING DIAGRAM
DI5VQ±04

± DIAGNOSTICSBODY CONTROL SYSTEM
DI±699
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check headlight relay (See page DI±693).
NG Replace the headlight relay.
OK
2 Check wireharness and connector between headlight relay and body ECU, bat-
tery and headlight relay (See page IN±41).
NG Repair or replace wireharness or connector.
OK
Proceed to next circuit inspection shown on
problem symptoms table (See page
DI±683).

I17121
8 8
1 2
9 B
BW±B W±B
L±B
L±B 2D
2K
J24 AA
J25 U1
Key Unlock
Warning Switch J11
J/C
J27 J272C Instrument
Panel J/B
IDJ/C A
12
KSW W±B Instrument Panel J/BBody ECU
DI±700
± DIAGNOSTICSBODY CONTROL SYSTEM
2001 PRIUS (RM778U)
Key unlock warning switch circuit
CIRCUIT DESCRIPTION
The key unlock warning switch goes on when the ignition key is inserted in the key cylinder and goes off when
the ignition key is removed.
The ECU operates the key confinement prevention function while the key unlock warning switch is on.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Check key unlock warning switch (See page BE±62).
NG Replace the key unlock warning switch.
OK
2 Check wireharness and connector between key unlock warning switch and body
ECU.
NG Repair or replace wireharness or connector.
DI7NP±01