How To Use The Diagnostic Chart And Inspection Procedure; Connector Connection And Terminal Inspection - Toyota T100 1996 Service Manual

IN−26
1996 TOYOTA T100 (RM449U)
INTRODUCTION − HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
HOW TO USE THE DIAGNOSTIC
CHART AND INSPECTION
PROCEDURE
1. CONNECTOR CONNECTION AND TERMINAL IN-
SPECTION
For troubleshooting, diagnostic trouble code charts or
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problem symptom table are provided for each circuit with
detailed inspection procedures on the following pages.
FI0046
When all the component parts, wire harnesses and con-
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nectors of each circuit except the ECU are found to be
normal in troubleshooting, then it is determined that the
problem is in the ECU. Accordingly, if diagnosis is per-
formed without the problem symptoms occurring,refer to
step 8 to replace the ECU, even if the problem is not in the
ECU. So always confirm that the problem symptoms are
occurring, or proceed with inspection while using the
symptom simulation method.
The instructions "Check wire harness and connector" and
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"Check and replace ECU" which appear in the inspection
procedure, are common and applicable to all diagnostic
trouble codes. Follow the procedure outlined below
whenever these instructions appear.
OPEN CIRCUIT:
This could be due to and a disconnected wire harness, faulty
contact in the connector, a connector terminal pulled out, etc.
HINT:
It is rarely the case that a wire is broken in the middle of
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it. Most cases occur at the connector. In particular, care-
FI0048
fully check the connectors of sensors and actuators.
Faulty contact could be due to rusting of the connector
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terminals, to foreign materials entering terminals or a de-
formation of connector terminals between the male and
female terminals of the connector. Simply disconnecting
and reconnecting the connectors once changes the
condition of the connection and may result in a return to
normal operation. Therefore, in troubleshooting, if no ab-
normality is found in the wire harness and connector
check, but the problem disappears after the check, then
the cause is considered to be in the wire harness or con-
nectors.
SHORT CIRCUIT:
This could be due to a connect between the wire harness and
the body ground or to a short occurred inside the switch etc.
HINT:
When there is a short circuit between the wire harness and body
ground, check thoroughly whether the wire harness is caught
in the body or is clamped properly.
IN02K−03