Lexus ES300 (1997 year). Service manual — part 435
N21224
Cruise Control ECU
1
B
Junction
Connector
B
W–R
10
1V
3
1W
W–R
2J
7
ECU–B
Engine Room J/B
1
2A
B
1
FL BLOCK
1
B–G
FL MAIN
Battery
J3
Instrument Panel J/B
F6
F8
W–R
BATT
C14
Short Pin
–
DIAGNOSTICS
CRUISE CONTROL SYSTEM
DI–517
669
1997 LEXUS ES300 (RM511U)
Back–up Power Source Circuit
CIRCUIT DESCRIPTION
The ECU back–up power source provides power even when the ignition is off and is used for DTC memory,
etc..
WIRING DIAGRAM
DI0F8–01
N20674
ECU–B
Fuse
Engine Room Junction Block No.2
N19924
BATT
(–)
(+)
DI–518
–
DIAGNOSTICS
CRUISE CONTROL SYSTEM
670
1997 LEXUS ES300 (RM511U)
INSPECTION PROCEDURE
1
Check ECU–B fuse.
PREPARATION:
Remove the ECU–B fuse from engine room junction block
No.2.
CHECK:
Check continuity of ECU–B fuse.
OK:
Continuity
NG
Check for short in all the harness and compo-
nents connected to the ECU–B fuse.
OK
2
Check voltage between terminal BATT of cruise control ECU connector and body
ground.
PREPARATION:
Remove the ECU with connector still connected.
CHECK:
Measure voltage between terminal BATT of ECU connector
and body ground.
OK:
Voltage: 10 – 14 V
OK
Proceed to next circuit inspection shown on
problem symptom table (See page
NG
Check and repair harness and connector be-
tween battery and cruise control ECU
(See page
).
AB0119
N19925
I00745
ON
CMS
(–)
(+)
–
DIAGNOSTICS
CRUISE CONTROL SYSTEM
DI–519
671
1997 LEXUS ES300 (RM511U)
Main Switch Circuit (Cruise Control Switch)
CIRCUIT DESCRIPTION
When the cruise control main switch is turned off, the cruise control does not operate.
WIRING DIAGRAM
See page
INSPECTION PROCEDURE
1
Check voltage between terminal CMS of cruise control ECU connector and body
ground.
PREPARATION:
(a)
Remove the ECU with connector still connected.
(b)
Turn ignition switch ON.
CHECK:
Measure voltage between terminal CMS of cruise control ECU
connector when main switch is held on and off.
OK:
Main switch
Voltage
OFF
10 – 14 V
ON
Below 0.5 V
OK
Proceed to next circuit inspection shown on
problem symptom table (See page
NG
DI0FA–01
N15969
3
5
DI–520
–
DIAGNOSTICS
CRUISE CONTROL SYSTEM
672
1997 LEXUS ES300 (RM511U)
2
Check main switch continuity.
PREPARATION:
(a)
Remove steering wheel center pad
(See page
(b)
Disconnect the control switch connector.
CHECK:
Check continuity between terminals 3 and 5 of control switch
connector when main switch is held on and off.
OK:
Switch position
Tester connection
Specified condition
OFF
3 – 5
No continuity
Hold ON
3 – 5
Continuity
NG
Replace control switch.
OK
3
Check harness and connector between cruise control ECU and main switch
(See page
).
NG
Repair or replace harness or connector.
OK
Check and replace cruise control ECU
(See page
).
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