2001 TOYOTA PRIUS Service Repair Manual

F12837
IDE6
2H
2B
2D5
42 3EMPS ECU
IG
IG S/W
Battery ECU±IG
W
IG B±GB±Y 1
23
6
DC/DC AM1
PGND 5J/C
J15
J14DE
W±B
W±B J11
J/C A
F11 B±Y
W±G B±Y
1 IG1 Relay
2
2I
2K8
F18 FL Block No. 2
FL Block No. 1
F1311
1
2
E5 A J17
J/C Instrument Panel J/B
MAIN
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±481
2001 PRIUS (RM778U)
DTC C1551/51 IG Power Source Circuit Malfunction
CIRCUIT DESCRIPTION
The EMPS ECU identifies ON or OFF status of ignition switch by this circuit.
DTC No.DTC Detecting ConditionTrouble Area
C1551/51The abnormal IG voltage value which is not within the specifi-
cation is input to EMPS ECU.
EMPS ECU

Power source circuit

Charging system
WIRING DIAGRAM
DI7R7±01

F12823
ECU±IG Fuse
Instrument Panel J/B
DI±482
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check ECU±IG fuse.
PREPARATION:
Remove the ECU±IG fuse from the instrument panel J/B.
CHECK:
Check the continuity of the ECU±IG.
OK:
Continuity
NG Check for short circuit in all harness and com-
ponents connected to ECU±IG fuse (See at-
tached wiring diagram).
OK
2 Check that the battery positive voltage when IG switch is OFF.
OK:
Voltage: 9 ± 14 V
NG Charge or replace the battery.
OK

F12824
ONIG
PGND
F12825
LOCK
PGND
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±483
2001 PRIUS (RM778U)
3 Check voltage between terminals IG and PGND of EMPS ECU connector.
PREPARATION:
Remove the EMPS ECU with connectors still connected.
CHECK:
Turn the ignition switch ON and measure the voltage between
terminals IG and PGND of EMPS ECU connector.
OK:
Voltage: 9 ± 14 V
OK Check and replace the EMPS ECU.
NG
4 Check continuity between terminals PGND of EMPS ECU connector and body
ground.
CHECK:
Measure the resistance between terminals PGND of EMPS
ECU connector and body ground.
OK:
Resistance: 1 W or less
NG Repair or replace harness or connector.
OK
Check for open and short circuit in harness and connector between EMPS ECU and ECU±IG fuse
(See page IN±41).

F12839
PIG
RLY E5
E61
2 B
GR IM1
IA21
7 B
GR 3
3 3
31 35
2 EMPS Relay
R±G B±R
Instrument Panel J/B
ECU±B
6
2G 2H1
W
F111
F101
WFL Block No. 1
DC/DC
F131
Engine Room R/B No. 3
3
321EMPS
FL Block No. 2 F18
MAIN
1
E52
PGND W±B
A J17
J/C
IG BatteryEngine Room R/B No. 3 DI±484
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
DTC C1552/52 PIG Power Source Circuit
CIRCUIT DESCRIPTION
When turning ignition switch ON, battery voltage is supplied to terminal PIG of EMPS ECU by EMPS relay
operation.
DTC No.DTC Detecting ConditionTrouble Area
C1552/52The abnormal motor power source voltage value which is not
within the specification is input to EMPS ECU.
EMPS ECU

Power source circuit
WIRING DIAGRAM
DI7R8±01