Introduction: Diagnosis Toyota Highlander I

FOR USING OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER

Observe The Following For Safety Reasons

1. Before using the OBD-II scan tool or TOYOTA hand-held tester, the OBD-II scan tool's instruction book or TOYOTA hand-held tester's operator manual should be read thoroughly.
2. Be sure to route all cables securely when driving with the OBD-II scan tool or TOYOTA hand- held tester connected to the vehicle. (i.e. Keep cables away from feet, pedals, steering wheel and shift lever).
3. Two persons are required when test driving with the OBD-II scan tool or TOYOTA hand-held tester, one person to drive the vehicle and one person to operate the OBD-II scan tool or TOYOTA hand-held tester.

HOW TO PROCEED WITH TROUBLESHOOTING

Carry out troubleshooting in accordance with the troubleshooting flowchart. Here, only the basic procedure is shown. Details are provided in Diagnostics articles, showing the most effective methods for each circuit. Confirm the troubleshooting procedures first for the relevant circuit before beginning troubleshooting of that circuit.

Scheme 7

Symptom Confirmation And Diagnostic Trouble Code Check

The diagnostic system in the Highlander fulfills various functions. The first function is the Diagnostic Trouble Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU memory at the time of occurrence, to be output by the technician during troubleshooting. Another function is the Input Signal Check which checks if the signals from various switches are sent to the ECU correctly. By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can be performed effectively. Diagnostic functions are incorporated in the following systems.

Scheme 8

Scheme 9

1. In the DTC check, it is very important to determine whether the problem indicated by the DTC is still occurring or has 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 DTC is directly related to the problem symptom or not. For this reason, the DTC should be checked before and after the symptom confirmation to determine the current conditions. If this is not done, it may, depending on the case, result in an unnecessary troubleshooting for normally operating systems, making it more difficult to detect the problem area, or trying to repair irrelevant areas. Therefore, always follow the procedure in the correct order and perform the DTC check.
2. A flow chart showing how to proceed with the troubleshooting using the diagnostic trouble code DTC check is shown below. This flow chart shows how to utilize the DTC check effectively, then by carefully checking the results, indicates how to proceed either to the DTC troubleshooting or to the troubleshooting of problem symptoms table.

Symptom Simulation

The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases, a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and environment in which the problem occurred in the customer's vehicle. No matter how much experience a technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem symptoms he will tend to overlook something important in the repair operation and make a wrong guess somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the engine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the problem can never be determined so long as the symptoms are confirmed with the engine hot condition or the vehicle at a standstill. Since vibration, heat or water penetration (moisture) is a likely cause for the problem (which is difficult to reproduce), the symptom simulation tests introduced here are effective measures in that the external causes are applied to the vehicle in a stopped condition.

Important Points in the Symptom Simulation Test: In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area or parts must also be found out. To do this, narrow down the possible problem circuits according to the symptoms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation test, judging whether the circuit being tested is defective or normal and also confirming the problem symptoms at the same time. Refer to symptom simulations (Scheme 11), for each system to narrow down the possible causes of the symptom.

Scheme 10

Diagnostic Trouble Code Chart

The inspection procedure is (Scheme 12) This table permits efficient and accurate troubleshooting using the diagnostic trouble codes displayed in the diagnostic trouble code check. Proceed with troubleshooting in accordance with the inspection procedure given in the diagnostic chart corresponding to the diagnostic trouble codes displayed. (Scheme 12)below, as an example.

Scheme 11

Problem Symptoms Table

Note. When the problem is not detected by the diagnostic system even though the problem symptom is present, it is considered that the problem is occurring outside the detection range of the diagnostic system, or that the problem is occurring in a system other than the diagnostic system.

The suspected circuits or parts for each problem symptom are shown in the problem symptoms table example. Use Problem Symptoms Tables when included in articles to troubleshoot the problem when a "Normal" code is displayed in the diagnostic trouble code check but the problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts should be checked.

Scheme 12

Circuit Inspection

Note. Some articles include figures containing information which when provided can be used in accordance with this procedure.

Scheme 13

Scheme 14

Scheme 15

Scheme 16

Scheme 17

Scheme 18

Scheme 19

Scheme 20

Scheme 21

Scheme 22

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

Scheme 30

1. Basic Inspection: Resistance measuring condition of electronic parts: Unless stated, all resistance is measured at an ambient temperature of 20°C (68°F). Because the resistance may be outside the specifications if measured at high temperatures immediately after the vehicle has been running, measurements should be made when the engine has cooled down. NOTE: Water proof connector cannot be checked from its back side, check by connecting the sub-harness. Do not damage the terminals moving the inserted tester needle. Handling of connectors: When removing the connector with a lock, press the connector toward the engagement and remove the lock by making the lock claw movable easily. When removing the connector, do not hold the harness, but hold the connector. Before connecting the connector, check that there are no deformation, damaged and missing terminals. Connection of the connector with a lock should be securely done until it makes a click sound. In case of checking the connector with a Toyota electrical tester, perform it at the back side (harness side) of the connector using a mini test lead. Connector checking points: Checking when the connector is connected: By holding the connector, check the inserted condition and locking efficiency (engaged condition). Checking when the connector is removed: Check by pulling the wire harness lightly (missing terminal, terminal crimping condition, core wire break). NOTE: When testing a gold-plated female terminal, always use a gold-plated male terminal. Checking of the contact pressure of the terminal, prepare the same terminal as a male terminal. By inserting it to a female terminal, check the engaged condition and sliding load. Repair method of connector terminal: In case there is any soil at the contact point, clean the contact point using an air gun or waste cloth. At this time, never polish the contact point using a sand paper as the plating may come off. In case of abnormal contact pressure, replace the female terminal. At this time, if a male terminal is gold-plated (gold color), use gold-plated female terminals and if it is silver-plated (silver color), use silver-plated female terminals. Handling of wire harness: In case of removing the wire harness, check the wiring and clamping condition before proceeding the work, so that it is restored correctly. Never twist, pull or slack off the wire harness more than necessary. Never make the wire harness come into contact with a high-temperature, rotating moving, vibrating or acute-angled part (edge of the panel, tip of the screw, etc.). When installing parts, never sandwich the wire harness between them. Never cut or break the cover of the wire harness. If it is cut or broken, replace it or securely repair it with vinyl tape.
2. Continuity Check (Open Circuit Check): NOTE: Measure the continuity while lightly shaking the wire harness vertically and horizontally. Disconnect the connectors at both ECU and sensor sides. Measure the resistance between the applicable terminals of the connectors. Resistance: One ohm or less.
3. Resistance Check (Short Circuit Check): Disconnect the connectors on both ends. Measure the resistance between the applicable terminals of the connectors and body ground. Be sure to carry out this check on the connectors on both ends. Resistance: One m/ohm or higher.
4. Visual Check And Contact Pressure Check: NOTE: The terminals should not come out when pulled lightly from the back. When testing a gold-plated female terminal, always use gold-plated male terminal. When the test terminal is pulled out more easily than others, there may be poor contact in that section. Disconnect the connectors at both ends. Check for rust or foreign material, etc. in the terminals of the connectors. Check crimped portions for looseness or damage and check that the terminals are secured in lock portion. Prepare a test male terminal and insert it in the female terminal, then pull it out.
5. Check Open Circuit: For the open circuit in the wire harness (Scheme 23), perform " a Continuity Check" or " b Voltage Check" to locate the section. Check the continuity: Disconnect connectors "A" and "C" and measure the resistance between them. In the case of (Scheme 24): Between terminal 1 of connector "A" and terminal 1 of connector "C", if no continuity (open). Between terminal 2 of connector "A" and terminal 2 of connector "C" means continuity. Therefore, it is found out that there is an open circuit between terminal 1 of connector "A" and terminal 1 of connector "C". Disconnect connector "B" and measure the resistance between the connectors. In the case of (Scheme 25): Between terminal 1 of connector "A" and terminal 1 of connector "B1" has continuity. Between terminal 1 of connector "B2" and terminal 1 of connector "C" there is no continuity (open). Therefore, it is found out that there is an open circuit between terminal 1 of connector "B2" and terminal 1 of connector "C". Check The Voltage: In a circuit in which voltage is applied (to the ECU connector terminal), an open circuit can be checked for by conducting a voltage check. (Scheme 26), with each connector still connected, measure the voltage between body ground and terminal 1 of connector "A" at the ECU 5V output terminal, terminal 1 of connector "B", and terminal 1 of connector "C", in that order. If the results are: 5V: Between terminal 1 of connector "A" and body ground 5V: Between terminal 1 of connector "B" and body ground Zero V: Between terminal 1 of connector "C" and body ground Then it is found out that there is an open circuit in the wire harness between terminal 1 of connector "B" and terminal 1 of connector "C".
6. Check Short Circuit: If the wire harness is shorted to ground as in (Scheme 27), locate the section by conducting a "continuity check with ground". Check the continuity with ground: Disconnect connectors "A" and "C" and measure the resistance between terminals 1 and 2 of connector "A" and body ground. In the case of (Scheme 28): Between terminal 1 of connector "A" and body ground there is continuity (short). Between terminal 2 of connector "A" and body ground there is NO continuity. Therefore, it is found out that there is a short circuit between terminal 1 of connector "A" and terminal 1 of connector "C". Disconnect connector "B" and measure the resistance between terminal 1 of connector "A" and body ground, and terminal 1 of connector "B2" and body ground. In the case of (Scheme 29): Between terminal 1 of connector "A" and body ground there is no continuity. Between terminal 1 of connector "B2" and body ground there is continuity (short). Therefore, it is found out that there is a short circuit between terminal 1 of connector "B2" and terminal 1 of connector "C".
7. Check And Replace ECU: First check the ECU ground circuit. If it is faulty, repair it. If it is normal, the ECU could be faulty, so replace the ECU with a normal functioning one and check that the symptoms disappear. Measure the resistance between the ECU ground terminal and the body ground. Resistance: One ohm or less. Disconnect the ECU connector, check the ground terminals on the ECU side and the wire harness side for bend and check the contact pressure.