toyota training course t874 engine control systems II ch01

These include: • Previous troubleshooting experience • Vehicle OBD system • Service Literature – Technical Information System TIS, Repair Manuals, Electrical Wiring Diagrams, and Technic

Section 1

Diagnostic Tools and Resources

There are many troubleshooting “tools” that can be used to accurately identify and troubleshoot driveability problems These include:

• Previous troubleshooting experience

• Vehicle OBD system

• Service Literature – Technical Information System (TIS), Repair Manuals, Electrical Wiring Diagrams, and Technical Service Bulletins

• Techstream There are also other resources at your disposal for those extraordinary situations where your best attempts fail to resolve the customer concerns:

• Technical Assistance hotline

• Area office assistance; STSs, FTSs, and FPEs With these resources available to you, even the most difficult customer concerns can be resolved while maintaining high standards for customer satisfaction

Your experience is one of the best resources you have Depending on the symptom or customer description of the driveability concern, you can often eliminate many sub-systems from your diagnostic investigations

It is important to note, however, this does not mean that troubleshooting

is performed in a random manner In fact, you will always fix the car faster and with more accuracy when you follow a systematic diagnostic approach

Diagnostic Tools and

Resources

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Previous Troubleshooting

Experience

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1) Verify the Complaint

• Does a problem exist?

• Intermittent or continuous?

• Customer Problem Analysis Check sheet from RM

• Clarify any and all unknowns

• Operating conditions

2) Determine the Related Symptoms

• Third-party repairs

• Body shop repairs

• Accessory installation

3) Analyze the Symptoms

• Look for related issues

• Is there more than one problem?

4) Isolate the Trouble

• Use appropriate tools

The 6-Step Diagnostic Process

The 6-Step Diagnostic Process Diagnostic Tools and Resources

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During the DTC check, it is very important to determine whether the problem indicated by the DTC either: 1) still occurs, or 2) occurred in the past but has returned to normal In addition, the DTC should be compared

to the problem symptom to see if they are related For this reason, DTCs should be checked before and after confirmation of symptoms (i.e., whether or not problem symptoms exist) to determine current system conditions, as shown in the flowchart

Never skip the DTC check Failing to check DTCs may, depending on the case, result in unnecessary troubleshooting for systems operating normally or lead to repairs not related to the problem Follow the procedures listed in the flowchart in the correct order

The flowchart shows how to proceed with troubleshooting using the DTC check Directions from the flowchart will indicate how to proceed either to DTC troubleshooting or to the troubleshooting of each problem symptom

Refer to the Introduction section of the Repair Manual (RM) for more information

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DTC Check

NOTE:

Knowing where to find appropriate information saves time and helps ensure accurate and timely repairs You should be familiar with and comfortable using the following information sources:

• Technical Information System (TIS)

• Repair Manual (RM)

• Electrical Wiring Diagram (EWD)

• Service Bulletins (SB)

• TAS support

Diagnostic Information

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If the DTCs are output after the DTC check procedure is completed, use the Repair Manual (RM) for the DTC diagnostic procedure

There is a lot of important information in the DTC troubleshooting sections of the Repair Manual (RM), such as the system description, monitor description, monitor strategy, typical enabling conditions, typical malfunction thresholds, wiring diagram, and inspection procedure

Carefully studying this information before beginning diagnosis may help you to better understand the issue and its cause

• The Navigation Tree allows easy navigation between documents.

• The Description provides an overview of the system operation.

• The Monitor Description provides an overview of the monitor

operation

• The Monitor Strategy provides information on related DTCs,

required sensors and components to operate (main and related), frequency of operation (continuous or once per driving cycle), duration of operation, MIL operation, and sequence of operation

• The Typical Enabling Conditions provides information on specific

conditions necessary for the monitor to operate, such as DTCs that cannot be present, system status, battery voltage, and other important conditions

DTC Information

• The Typical Malfunction Thresholds provides information on what

will cause the monitor to fail and a DTC to set

• The Component Operating Range provides component

specifications (if applicable)

• The Wiring Diagram provides a thorough wiring diagram of the

system and components

• The Inspection Procedure provides the procedure for diagnosing the

cause of the DTC

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The Repair Manual contains the following sections (may vary by model and year):

• Precaution lists unique service requirements specific to the vehicle.

• Definition of Terms provides descriptions of system terminology.

• System Diagram is a high-level electrical wiring diagram of the

system

• Basic Inspection describes fundamental checks of air, fuel, and

spark

• Readiness Monitor Drive Pattern provides charts that describe

drive patterns for specific monitors

• Problem Symptoms Table is used to aid diagnosis when there is no

DTC displayed

• Terminals of ECM shows the ECM and its connectors as you

would view them

• Diagnosis System explains scan tool connection, usage, and trip

detection logic, and includes a DLC3 diagram

• Freeze Frame Data lists descriptions of Techstream parameters

recorded during a freeze frame

• Fail-Safe Chart indicates ECM strategy when certain DTCs are set.

• Data List / Active Test provides a comprehensive list of data list

parameters and active tests

• Diagnostic Trouble Code Chart displays all applicable DTCs,

possible trouble areas, and links to DTC diagnosis sections

Repair Manual

There is a Terminals of ECM document specific to each vehicle and model year The document includes an illustration of all ECM terminals and their location on the ECM connector Below the illustration is a chart

of information for each terminal:

• The Symbols (Terminal No.) column provides the names and ECM

connector locations (terminal and corresponding ground)

• The Wiring Colors column provides the wire colors (terminal and

corresponding ground)

• The Terminal Descriptions column describes terminal function.

• The Conditions column describes the appropriate testing

conditions

• The Std Voltages/Specified Condition column provides the

standard operating range

The bottom of the Terminals of ECM document also includes waveform examples for various engine system sensors These examples are a useful reference when using an oscilloscope during diagnosis

Terminals of ECM

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