System diagnostic trouble code check input signal

System
Diagnostic Trouble
Code Check
Input Signal Check
(Sensor Check)
Other Diagnosis
Function
Engine
Automatic Transmission
Anti–Lock Brake System (& Traction Control)
Supplemental Restraint System
Cruise Control
f (with Test Mode)
f (with Test Mode)
f
f
f
f
f
f
f
Diagnostic Test
Mode
Diagnostic Test
Mode
In diagnostic trouble code check, it is very important to determine whether the problem indicated by the diag-
nostic trouble code is still occurring or occurred in the past but returned to normal at present. In addition,
it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic
trouble code is directly related to the problem symptom or not. For this reason, the diagnostic trouble codes
should be checked before and after the symptom confirmation to determine the current conditions, as shown
in the table below. If this is not done, it may, depending on the case, result in unnecessary troubleshooting
for normally operating systems, thus making it more difficult to locate the problem, or in repairs not pertinent
to the problem. Therefore, always follow the procedure in correct order and perform the diagnostic trouble
code check.

Diagnostic trouble code check
Making a note of and clearing of the diagnostic trouble codes displayed
Symptom confirmation
No problem symptoms
exist
Problem symptoms
exist
Simulation test using the symptom
simulation methods
D Normal code displayed
D Problem symptoms exist
D Normal code displayed
D No problem symptoms exist
Diagnostic trouble code check
Troubleshooting of problem indicated
by diagnostic trouble code
D Diagnostic trouble code displayed
D Problem symptoms exist
System Normal
Troubleshooting of each
problem symptom
If a diagnostic trouble code was
displayed in the initial diagnostic
trouble code check, it indicates
that the trouble may have occurred
in a wire harness or connector in
that circuit in the past. Therefore,
check the wire harness and con-
nectors (See page IN–27 ).
IN–20
– INTRODUCTION HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
20 AuthorĂ: DateĂ:
1997 LEXUS ES300 (RM511U)
Taking into account the above points, a flow chart showing how to proceed with troubleshooting using the
diagnostic trouble code check is shown below. This flow chart shows how to utilize the diagnostic trouble
code check effectively, then by carefully checking the results, indicates how to proceed either to diagnostic
trouble code troubleshooting or to troubleshooting of problem symptoms.

V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR
1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.