Page 810 of 1943
A14147
H14Hybrid Vehicle
Control ECU
H14
BatteryMAIN
B±G1 1
F1811 1
111
F13 2
3
2
2 Engine Room J/BSTP
ST1± G±W
J15 E
2 J14D J/C
G±W S3
Stop Light
SW
R±B
R±B4B±Y B±W B±W B
B
J24 J25 ID1J/C
B±W
I15
Ignition SW
W±RW±R
67
9
IG2AM2
Instrument Panel J/B
STOP 2C
2K2H 2G9
1J 1BAM2
B
W
F12 F11
DC/DC
Fusible Link Block No. 1 Fusible Link
Block No. 16
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
DI±215
2001 PRIUS (RM778U)
DTC P1520 Stop Light Switch (Cruise Control System)
Malfunction
CIRCUIT DESCRIPTION
The HV ECU detects the malfunction of the cruise control system and inhibits the operation of the cruise
control.
It detects faulty output of the STP and ST1± signals sent from the stop light switch or an error signal from
the brake ECU.
DTC P1520 ± Information code 115
INF. code.Detecting ConditionTrouble Area
11 5Open or short in stop light switch circuit
Stop light switch
Wire harness
Brake ECU
WIRING DIAGRAM
DI82R±02
Page 811 of 1943
DI±216
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Is DTC of brake ECU being output?
YES Check DTC of brake ECU (See page DI±358).
NO
2 Check voltage between terminal 2, 3 of stop light switch and body ground.
NG Repair or replace wire harness or connector.
OK
3 Check for open and short in wire harness between stop light switch and termi-
nals STP, ST1± of HV ECU (See page IN±41).
NG Repair or replace wire harness.
OK
Check and replace stop light switch (See page BE±32).
Page 812 of 1943
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
DI±217
2001 PRIUS (RM778U)
DTC P1566 Cruise Control System Malfunction
CIRCUIT DESCRIPTION
The HV ECU and the brake ECU monitor the same STP signal. If any difference is identified between both
received signals, the HV ECU outputs an error.
DTC P1566 ± Information code 116
INF. code.Detecting ConditionTrouble Area
11 6When STP signal of HV ECU is inconsistent with that of brake
ECU, with cruise control indicator ON.Brake ECU
Wire harness
Stop light switch
WIRING DIAGRAM
Refer to DI±215.
INSPECTION PROCEDURE
1 Is DTC of brake ECU being output (See page DI±351)?
YES Check DTC of brake ECU (See page DI±351).
NO
2 Check for +B short in wire harness between stop light switch and terminals STP,
ST1±of HV ECU (See page IN±41).
HINT:
Under the normal condition, the voltage of the HV ECU STP terminal is 0V when the brake pedal is released
with the ignition OFF. If there is any output of voltage at this time, the stop light switch circuit has +B short.
NG Repair or replace wire harness.
OK
DI82S±02
Page 813 of 1943
DI±218
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
2001 PRIUS (RM778U)
3 Check for open and short in wire harness between stop light switch and brake
ECU.
NG Repair or replace wire harness.
OK
Check and replace stop light switch (See page BE±32).
Page 821 of 1943
DI±228
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
2001 PRIUS (RM778U)
CIRCUIT DESCRIPTION
The HV ECU gives warning to the driver and performs the fail safe control, according to the abnormal signal
received from the battery ECU.
DTC P3004 ± Information code 133
INF. Code.Detecting ConditionTrouble Area
133Input of abnormal signal from battery ECUHV battery system
INSPECTION PROCEDURE
If the information code 133 output, after confirming the DTC of the HV Battery ECU, check and repair the
applicable DTC. After repairing it, record the DTC of the HV ECU, freeze frame data and history of operation.
Then, clear the DTC and check it one more time after starting the system again (ºREADYº light ON).
Page 833 of 1943
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
DI±241
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check for open and short in wire harness between HV ECU terminals (ETH+,
ETH±) and ECM terminals (ETH+, ETH±) (See page IN±41).
NG Repair or replace wire harness.
OK
Replace ECM.
CIRCUIT DESCRIPTION
DTC P3106 ± Information code 212
INF. Code.Detecting ConditionTrouble Area
212Input of abnormal signal from ECMECM
INSPECTION PROCEDURE
If the information code 212 is output, after confirming the DTC of the ECM, check and repair the applicable
DTC. Prior to repairing it, record the DTC of the HV ECU, freeze frame data and history of operation. Then,
clear the DTC and check it one more time after starting the system again (ºREADYº light ON).
CIRCUIT DESCRIPTION
DTC P3106 ± Information code 394
INF. Code.Detecting ConditionTrouble Area
394When ECM does not operateECM
INSPECTION PROCEDURE
If the information code 394 is output, check and repair the ECM power source circuit. If there is no problem
in the power source circuit, replace the ECM. Prior to the repair, record the DTC of the HV ECU, freeze frame
data and history of operation and clear them. Then, start the system one more time (ºREADYº light ON) and
check the DTC again.
Page 837 of 1943
DI±246
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check for open, short and +B short in wire harness between HV ECU terminals
(HTB+, HTB±, BTH+, BTH±) and brake ECU terminals (HV1+, HV1±, HVO+, HVO±)
(See page IN±41).
HINT:
Confirm that there is no open circuit in the wire harness. If the voltage of each HV ECU terminals (HTB+,
HTB±, BTH+ and BTH±) is always more than 5 V with the ignition ON, the brake ECU communication circuit
has +B short.
NG Repair or replace wire harness.
OK
Replace brake ECU.
CIRCUIT DESCRIPTION
DTC P3109 ± Information code 222
INF. Code.Detecting ConditionTrouble Area
222When abnormal data is received from brake ECU.Brake ECU
INSPECTION PROCEDURE
If the information code 222 is output, after confirming the DTC of the brake ECU, check and repair the appli-
cable DTC. Prior to repairing it, record the DTC of the HV ECU, freeze frame data and history of operation.
Then, clear the DTC and check it one more time after starting the system again (ºREADYº light ON).
Page 841 of 1943
DI±250
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check for open, short and +B short in wire harness between HV ECU terminals
(Cont1, Cont2, Cont3) and system main relay terminals (See page IN±41).
HINT:
Confirm that there is no open circuit in the wire harness. If the battery voltage is always applied to the HV
ECU Cont1, Cont2 and Cont3 terminals with the ignition ON (ºREADYº light OFF), the system main relay
has +B short.
NG Repair or replace wire harness.
OK
2 Is any of the information code 231, 232 or 233 recorded?
NO Replace HV ECU.
YES
Replace HV ECU and system main relay.
