2001 TOYOTA PRIUS Service Repair Manual

N17520
N17520
± DIAGNOSTICSCRUISE CONTROL SYSTEM
DI±649
2001 PRIUS (RM778U)

Pull the cruise control switch to CANCEL
(e) Inspect the RESUME switch.
(1) Push the main switch ON.
(2) Drive at a desired speed (40 km/h (25 mph) or high-
er).
(3) When operating one of the followings, check that
the cruise control system is cancelled and that the
normal driving mode is reset.

Depress the brake pedal

Shift to except D range (A/T)

Pull the cruise control switch to CANCEL
(4) After the control switch is turned to RES/ACC at the
driving speed of more than 40 km/h (25 mph), check
that the vehicle restores the speed prior to the can-
cellation.
5. INPUT SIGNAL CHECK
(Using hand±held tester)
(a) Connect the hand±held tester to DLC3
(b) Check the control switch (MAIN, CANCEL, SET/COAST,
RES/ACC)

DI±654
± DIAGNOSTICSCRUISE CONTROL SYSTEM
2001 PRIUS (RM778U)
CIRCUIT INSPECTION
DTC P1520 Stop light switch circuit
CIRCUIT DESCRIPTION
When the brake pedal is depressed, the stop light switch sends a signal to the hybrid vehicle control ECU.
When the hybrid vehicle control ECU receives this signal, it cancels the cruise control.
A fail±safe function is provided so that the cancel functions normally, even if there is a malfunction in the stop
light signal circuit.
The cancel condition is that battery voltage is supplied to terminal STP.
When the brake is on, battery voltage is normally applied through the STOP fuse and stop light switch to
terminal STP of the hybrid vehicle control ECU, and the hybrid vehicle control ECU turns the cruise control
OFF.
If the harness connected to terminal STP has an open circuit, terminal STP will have battery voltage and
the cruise control will be turned OFF.
DTC No.Detection ItemTrouble Area
P1520Stop light switch circuit.

Stop light switch

Harness or connector between hybrid vehicle control ECU
and stop light switch circuit

Hybrid vehicle control ECU
DI7NI±01

I15477
Instrument Panel J/B
FL Block No. 2S3
Stop Light SW I15
Ignition SW
Engine Room J/BHybrid Vehicle
Control ECU
J25 ID1B±Y
ST1± IG2 AM2
1G±W
2
R±B2
H14
STP 1
H14 B±W
34
6 B±W
J24
B C B±W W±R
7
6
2
2C
15A AM21
2GW±R
9
1J 2
1B B
1
F12B±G
120A MAIN
Battery1
F13
1
F18J15
D J14
E G±W
Instrument Panel J/B
9
2K15A STOP
W
100A DC/DC
F11 1
2H
FL Block No. 1
1
F131
B±GS3
Stop Light SW J/C
J/C
FL Block No. 1
± DIAGNOSTICSCRUISE CONTROL SYSTEM
DI±655
2001 PRIUS (RM778U)
WIRING DIAGRAM

I19096
ON
STP
(+) (±)
DI±656
± DIAGNOSTICSCRUISE CONTROL SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check operation of stop light.
CHECK:
Check that stop light comes on when brake pedal is depressed, and turns off when brake pedal is released.
NG Check stop light system (See page BE±2).
OK
2 Check voltage between terminal STP of hybrid vehicle control ECU connector
and body ground.
PREPARATION:
(a) Remove the hybrid vehicle control ECU with connectors
still connected.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminal STP of hybrid vehicle con-
trol ECU connector and body ground, when the brake pedal is
depressed and released.
OK:
Depressed10 ± 14 V
ReleasedBelow 1 V
OK Proceed to next circuit inspection shown in
problem symptom table (See page DI±648).
NG

I19096
ON
ST1±
(+) (±)
± DIAGNOSTICSCRUISE CONTROL SYSTEM
DI±657
2001 PRIUS (RM778U)
3 Check voltage between terminal ST1± of hybrid vehicle control ECU connector
and body ground.
PREPARATION:
(a) Remove the hybrid vehicle control ECU with connectors
still connected.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminal ST1± of hybrid vehicle con-
trol ECU connector and body ground, when the brake pedal is
depressed and released.
OK:
DepressedBelow 1 V
Released10 ± 14 V
OK Proceed to next circuit inspection shown in
problem symptoms table (See page DI±648).
NG
4 Check wire harness and connector between terminal STP of hybrid vehicle con-
trol ECU and stop light switch, and terminal ST1± of hybrid vehicle control ECU
and stop light switch (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace hybrid vehicle control
ECU (See page DI±174
).