2001 TOYOTA PRIUS warning light

DI±466
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)C1557/57
(DI±488)
Memory of overheat prevention control±
C1558/58
(DI±488)Memory of voltage drop at motor power supply±
C1559/59
(DI±488)Memory of continuous control under high load±
Always ON
(DI±489)Malfunction in EMPS ECU

Power source circuit

EMPS ECU

PS warning light circuit

F12840
EMPS ECU
WL
E67
Y 3
IP1 L 11 Multiinformation Display
22
L
Instrument Panel J/B
IG1 Relay
3
51
2H GAUGE
2A5
W
FL Block No. 1
1
F11 F131
B±G
1 MAIN FL Block No. 2 F18
BatteryDC/DC
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±491
2001 PRIUS (RM778U)
DTC C1556/56 P/S Warning Light Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
C1556/56There is a malfunction in PS warning light circuit.
Multiinformation display

EMPS ECU
WIRING DIAGRAM
DI7RB±01

DI±494
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
DTCAlways ONMalfunction in EMPS ECU
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
Always ONThere is a malfunction in the EMPS ECU internal circuit.

Power source circuit

EMPS ECU

PS warning light circuit
INSPECTION PROCEDURE
1 Is DTC output?
Check DTC on page DI±460.
YES Repair circuit indicated by output code.
NO
2 Is normal code displayed?
YES Check and replace EMPS ECU.
NO
3 Does PS warning light goes off?
YES Check for open or short circuit in harness and
connector between ECU±IG fuse and EMPS
ECU (See page IN±41).
NO
DI7RD±01

± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±495
2001 PRIUS (RM778U)
4 Check battery positive voltage.
PREPARATION:
Start the engine.
CHECK:
Check the battery positive voltage.
OK:
Voltage: 9 ± 14 V
NG Check and repair charging system.
OK
5 Check operation of PS warning light.
PREPARATION:
(a) Turn the ignition switch OFF.
(b) Disconnect the connector from the EMPS ECU.
(c) Turn the ignition switch ON.
CHECK:
Check the PS warning light goes OFF.
OK Check and replace EMPS ECU.
NG
Check for short circuit in harness and connector between multiinformation display and EMPS
ECU, multiinformation display and DLC3 (See page IN±41).

F12842
EMPS ECU
Tc
E63
P±B
C CJ16
J/C
P±B 2
ID1 P±B
E EJ26
J/C
P±B 13
Tc
5
SGBR14
ID2BR
BR 14
IO1
EB DLC3 DI±496
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
2001 PRIUS (RM778U)
Tc Terminal Circuit
CIRCUIT DESCRIPTION
Connecting terminals Tc and CG of the DLC3 causes the EMPS ECU to display the DTC by flashing the PS
warning light.
WIRING DIAGRAM
DI7RE±01

F09678
ON
Tc
CG
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±497
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminals Tc and CG of DLC3.
CHECK:
Turn the ignition switch ON and measure the voltage between
terminals Tc and CG of the DLC3.
OK:
Voltage: 9 ± 14 V
OK If PS warning light does not blink even after Tc
and CG are connected, EMPS ECU may be de-
fective.
NG
2 Turn the ignition switch OFF, and check for open and short circuit in harness
and connector between EMPS ECU and DLC3, and DLC3 and body ground (See
page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace EMPS ECU.

F09679
ON
Ts
CG
± DIAGNOSTICSELECTRIC MOTOR POWER STEERING
DI±499
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminals Ts and CG of DLC3.
CHECK:
Turn the ignition switch ON and measure the voltage between
terminals Ts and CG of the DLC3.
OK:
Voltage: 9 ± 14 V
OK If PS warning light repeats turning ON and OFF
even after Ts and CG are connected, EMPS ECU
may be defective.
NG
2 Turn the ignition switch OFF, and check for open and short circuit in harness
and connector between EMPS ECU and DLC3, DLC3 and body ground (See page
IN±41).
NG Repair or replace harness or connector.
OK
Check and replace EMPS ECU.

DI6OY±07
H15218
H10658
DLC3
CG Tc
DI±502
± DIAGNOSTICSSUPPLEMENTAL RESTRAINT SYSTEM
2001 PRIUS (RM778U)
PRE±CHECK
1. SRS WARNING LIGHT CHECK
(a) Turn the ignition switch to the ON position and check that
the SRS warning light lights up.
(b) Check that the SRS warning light goes out after approx.
6 seconds.
HINT:

When the ignition switch is at ON and the SRS warning
light remains on or flashes, the airbag sensor assembly
has detected a malfunction code.

If, after approx. 6 seconds have elapsed, the SRS warn-
ing light sometimes lights up or the SRS warning light
lights up even when the ignition switch is OFF, a short in
the SRS warning light circuit can be considered likely.
Proceed to ºSRS warning light circuit malfunctionº on
page DI±632.
2. DTC CHECK (Using diagnosis check wire)
(a) Present troubles codes:
Output the DTC.
(1) Turn the ignition switch to the ON position and wait
for approx. 20 seconds.
(2) Using SST, connect terminals Tc and CG of the
DLC3.
SST 09843±18020
NOTICE:
Pay due attention to the terminal connecting position to
avoid a malfunction.
(b) Past troubles codes:
Output the DTC.
(1) Using service wire, connect terminals Tc and CG of
the DLC3.
SST 09843±18020
(2) Turn the ignition switch to the ON position and wait
for approx. 20 seconds.
NOTICE:
Pay due attention to the terminal connecting position to
avoid a malfunction.