2001 TOYOTA PRIUS check engine

Absence of
Master D6 01
(Communication
Control)Component in which this code is re-
corded has been disconnected
from system with ignition in ACC or
ON. Or, when this code was re-
corded, multi±display assembly
was disconnected.
Check harness for power supply
system of multi display.

Check harness for communica-
tion system of multi display.

Check harness for power supply
system of navigation ECU.

Check harness for communica-
tion system of navigation ECU.
Connection
Check Error D7 01 *6
(Communication
Control)Component in which this code is re-
corded has been disconnected
from system after engine start.
Or, when this code was recorded,
multi±display assembly was dis-
connected.
D6
Check harness for power supply
system of multi display.

Check harness for communica-
tion system of multi display.

Check harness for power supply
system of navigation ECU.

Check harness for communica-
tion system of navigation ECU.
Transmission
Error DC 01
(Communication
Control)Transmission to component shown
by auxiliary code has been failed.
(This code does not necessarily
mean actual failure.)If same auxiliary code is recorded in
other component(s), check harness
for power supply and communica-
tion system of components shown
sub code.
Master Reset
(Momentary
Interruption) DD 01
(Communication
Control)
Check harness for power supply
system of multi±display assembly.

Check harness for communica-
tion system of multi±display assem-
bly.

If error occurs frequently, replace
multi±display assembly.
Registration
Completion
Instruction
Error E0 01
(Communication
Control)ºRegistration Completion Instruc-
tionº command from multi display
cannot be received.Since this DTC is provided for engi-
neering, it may be detected when
no actual failure exists.
ON/OFF
Instruction
Parameter
Error E2 01
(Communication
Control)Error is detected in ON/OFF control
command from multi±display as-
sembly.Replace multi±display assembly.
Registration
Request
Transmission E3 01
(Communication
Control)Since this DTC is provided for engi-
neering, it may be detected when
no actual failure exists.
Registration Request command
is output from slave component.

By reception of connection check
Instruction, Registration Request
command is output from sub±mas-
ter component.After engine is started, multi±dis-
play assembly was disconnected
from system.
Master Error DF 01
(Communication
Control)Due to defective condition of com-
ponent with a display, master func-
tion is switched to audio equip-
ment . Error occurs in communica-
tion between sub±master (audio)
and master component.
Check harness for power supply
of multi±display assembly.

Check harness for communica-
tion system of multi±display assem-
bly.

Check harness for communica-
tion system between multi±display
assembly and sub±master compo-
nent.
Plural Frame
Abort E4 01
(Communication
Control)
Since this DTC is provided for en-
gineering purpose, it may be de-
tected when no actual failure exists. Plural frame transmission is
aborted.
*6: When 210 sec. has passed after pulling out the power supply connector of the master component with the ignition
switch in ACC or ON, this code is stored. DI±818
± DIAGNOSTICSNAVIGATION SYSTEM
2001 PRIUS (RM778U)

± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±875
2001 PRIUS (RM778U)42
(DI±909)
Air inlet control servomotor circuit

Air inlet control servomotor

Air inlet damper position sensor

Harness or connector between air inlet control servomotor
and A/C amplifier

A/C amplifier
43
(DI±912)Air outlet control servomotor circuit

Air outlet control servomotor

Air outlet damper position sensor

Harness or connector between air outlet control servomotor
and A/C amplifier

A/C amplifier
HINT:

*1: If the room temp. is approx. ±18.6°C (±3.7°F) or lower, trouble code 11 may be output even though
the system is normal.

*2: If the ambient temp. is approx. ±52.9°C (±61.4°F) or lower, a malfunction code may be output even
though the system is normal.

*3: If the check is being performed in a dark place, DTC 21 (solar sensor circuit abnormal) could be
displayed.

*4: To confirm DTC 22, perform the following steps.
(1) With the engine is running, enter the DTC check mode.
(2) Enter actuator check mode and set the operation to step NO. 1.
(3) Check that the DTC 22 is output.

S05502
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±891
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check engine coolant temp. sensor using hand±held tester.
PREPARATION:
Connect the hand±held tester to the DLC3.
CHECK:
Check the engine coolant temp. sensor using DATA LIST.
OK Check or replace A/C amplifier.
NG
2 Check engine coolant temp. sensor.
PREPARATION:
Remove engine coolant temp. sensor.
CHECK:
Measure resistance between terminals.
OK:
Resistance is within acceptable zone on chart.
Water temperatureResistance
20°C (68°F)2 ± 3 kW
80°C (176°F)0.2 ± 0.4 kW
NG Replace engine coolant temp. sensor.
OK

DI±892
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
3 Check for open and short in harness and connector between ECM and engine
coolant temp. sensor (See page IN±41).
NG Repair or replace harness or connector.
OK
Check multiplex communication system (See page DI±750).

I18005
2
4
N02774
0.2 V/Din.0 V
20 msec/Division (Idling)LCK1 LOCK signal waveform
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±897
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check compressor.
PREPARATION:
(a) Check compressor drive belt tension (See page AC±15).
(b) Check if the compressor does not lock during operation with engine started and blower switch and A/C
switch ON.
NG Adjust drive belt tension or repair compressor.
OK
2 Check compressor lock sensor.
PREPARATION:
Disconnect compressor lock sensor connector.
CHECK:
Measure resistance between terminals 2 and 4 of compressor
lock sensor connector.
OK:
Resistance : at 20 °C (68 °F) : 65 ± 125 W
Reference : Inspection using oscilloscope
During cranking or idling, measure voltage between terminals
LOCK and SGLOCK of A/C amplifier.
HINT:
The correct waveform appears as shown in the illustration on
the left.
NG Replace compressor.
OK

Max. COOL e 20.5 (66)
21.0 e 23.5 (67 e72)±10 % (Fully closed)Cool air comes out Temp. Setting °C (°F)Air Mix Damper
Condition
24.0 e 26.0 (73 e77)
26.5 e 29.0 (78 e83)
29.5 (84) eMax. WARM100 % (Fully opened)
""
50 %
"
Warm air comes out
DI±912
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Actuator check.
PREPARATION:
(a) Warm up the engine.
(b) Set to the actuator check mode (See page DI±866).
CHECK:
Operate the temperatur control switch and check the operation of the air mix damper and the condition of
the blower.
OK:
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±874).
NG

BE1850 BE1844I00312125
3
125
3
4
4
I18394
Engine Room J/B
HTR
Fuse
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±927
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check heater main relay.
PREPARATION:
Remove heater main relay from engine room J/B.
CHECK:
Check continuity between each pair of terminals of heater main
relay shown below.
OK:
Tester connectionSpecified condition
1 ± 4No continuity
2 ± 4Continuity
3 ± 562.5 ± 90.9 W
PREPARATION:
Apply battery positive voltage between terminals 3 and 5.
CHECK:
Check continuity between each pair of terminal shown below.
OK:
Tester connectionSpecified condition
1 ± 2Continuity
2 ± 4No continuity
NG Replace hater main relay.
OK
2 Check HTR fuse
PREPARATION:
Remove HTR fuse from engine room J/B.
CHECK:
Check continuity of HTR fuse.
OK:
Continuity exists.
NG Check for short in all the harness and compo-
nents connected to the HTR fuse (See page
IN±41).
OK

I18169
MGC
(+)
(±) ON
Z18060
15 2
3
12 3 5
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±933
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminal MGC of A/C amplifier and body ground.
CHECK:
(a) Start engine.
(b) Push AUTO SW.
(c) Measure voltage between terminal MGC of A/C amplifier
connector and body ground when A/C switch is On and
OFF.
OK:
A/C switchVoltage
ONBelow 0.7 V
OFF10 ± 14 V
OK Go to step 5.
NG
2 Check magnetic clutch relay.
PREPARATION:
Remove magnetic clutch relay from engine room J/B.
CHECK:
Check continuity between each pair of terminals shown below
of magnetic clutch relay.
OK:
Tester connectionSpecified condition
1 ± 262.5 ± 90.9 W
3 ± 5No continuity
PREPARATION:
Apply battery positive (+) voltage between terminals 1 and 2.
CHECK:
Check continuity between terminals 3 and 5.
OK:
Continuity exists.
NG Replace magnetic clutch relay.
OK