Introduction: Diagnosis Lexus RX II

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

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

1. Vehicle brought to workshop
2. Customer problem analysis Ask the customer about the conditions and environment when the problem occurred.
3. Symptom confirmation and DTC (and freeze frame data) check Check the battery positive voltage. Voltage: 11 to 14 V (Engine stopped) Visually check the wire harness, connectors and fuses for open and short, etc. Warm up the engine to the normal operating temperature. Confirm the problem symptoms and conditions, and check for DTCs according to the related chart. OK: Go to step 5 NG: GO TO NEXT STEP.
4. DTC chart Check the results obtained in step 3 , then confirm the inspection procedures for the system or the part which should be checked using the DTC chart. Go to step 6
5. Problem symptoms chart Check the results obtained in step 3 , then confirm the inspection procedures for the system or the part which should be checked using the problem symptoms table.
6. Circuit inspection or parts inspection Confirm the circuit for the system or the part which should be checked using the problem symptoms table or the results obtained in step 4.
7. Repair Repair the affected system or part in accordance with the instructions in step 6.
8. Confirmation test. After completing repairs, confirm that the problem has been solved (If the problem does not recur, perform a confirmation test under the same conditions and in the same environment as when it occurred for the first time). END

SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE

HINT

1. The diagnostic system in LEXUS RX330 has various functions. The first function is the Diagnostic Trouble Code (DTC) Check, in which a malfunction in the signal circuits to the ECU is stored in code form in the ECU memory. 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, it is possible to quickly narrow down potential problem areas and troubleshooting can be performed effectively. The diagnostic functions are incorporated in the following systems in the LEXUS RX330.

DIAGNOSTIC TROUBLE CODE CHART

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 during the problem symptom check, a check must be made on 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 symptom confirmation to determine the current conditions. If this is not done, it may, depending on the case, result in unnecessary troubleshooting for systems that are operating normally. This would make more difficult to detect the problem area or to try to repair irrelevant areas. Therefore, always follow procedures in the correct order and perform the DTC check.
2. A flow chart showing how to proceed with troubleshooting using the diagnostic trouble code (DTC) check is shown in «DIAGNOSTIC TROUBLE CODE CHART»(ref-215923-S27251048042006011900000) . This flow chart shows how to utilize the DTC check effectively. Then by carefully checking the results, this chart indicates how to proceed either to the DTC troubleshooting or to the troubleshooting of the problem symptoms table.

1. DTC check
2. Make a note of the DTCs displayed and then clear the memory
3. Symptom confirmation SYMPTOM CHART a Symptoms exist b No symptoms exist a: Go to step 5 b: Go to Next Step
4. Simulation test using symptom simulation methods
5. DTC check DTC CHART a DTC displayed b Normal code displayed a: Troubleshooting of problem indicated by DTC b: Go To Next Step
6. Symptom confirmation

SYMPTOM CHART

If a DTC is displayed in the initial DTC check, it indicates that a trouble may have occurred in a wire harness or connector in that circuit in the past. Therefore, check the wire harness and connectors (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).

1. a: System normal
2. b: Troubleshooting of each problem symptom

The problem is still occurring in a place other than the diagnostic circuit (The DTC displayed first is either for a past problem or a secondary problem).

SYMPTOM SIMULATION

HINT

The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. Then the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be simulated. 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 when the engine is hot or when the vehicle at is 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 a point that the external causes are applied to the vehicle in a stationary condition.

Important points in the symptom simulation test

In the symptom simulation test, the problem symptoms should be confirmed, and the problem area or parts must also be discovered. To do so, reduce the possible problem circuits according to the symptoms before starting this type of test and have the hand-held tester connected 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 the problem symptoms table of each system to narrow down the possible causes of the symptom.

Scheme 43

Scheme 44

Scheme 45

Scheme 46

1. VIBRATION METHOD: When vibration seems to be the major cause. PART AND SENSOR Apply slight vibration with your finger to the parts the sensor considered to be the problem cause and check whether the malfunction occurs. HINT: Applying strong vibration to relays may result in open relays. CONNECTORS Slightly shake the connector vertically and horizontally. WIRE HARNESS Slightly shake the wire harness vertically and horizontally. The connector joint and fulcrum of the vibration are the major areas that should be checked thoroughly.
2. HEAT METHOD: If the problem seems to occur when the area in question is heated. Heat the component that is the possible cause of the malfunction with a hair dryer or similar object. Check if the malfunction occurs. NOTE: Do not heat the components to more than 60°C (140°F) (Temperature is limited to keep the components from being damaged). Do not apply heat directly to the parts in the ECU.
3. WATER SPRINKLING METHOD: When the malfunction seems to occur on a rainy day or in high-humidity. Sprinkle water onto the vehicle and check if the malfunction occurs. NOTE: Never sprinkle water directly onto the engine compartment, but indirectly change the temperature and humidity by spraying a mist of water onto the radiator front surface. Never apply water directly onto the electronic components. HINT: If a vehicle is subject to water leakage, the leaking water may contaminate the ECU. When testing a vehicle with a water leakage problem, this factor must also be considered.
4. OTHERS: If the malfunction seems to occur when electrical load is excessive. Turn on all the electrical equipment including the heater blower, headlights, rear window defogger, etc., and check if the malfunction occurs.

DIAGNOSTIC TROUBLE CODE CHART

The inspection procedures are (Scheme 47) This table allows efficient and accurate troubleshooting using the diagnostic trouble codes displayed in the diagnostic trouble code chart. Proceed with troubleshooting in accordance with the inspection procedures listed in the diagnostic chart corresponding to the diagnostic trouble codes displayed. The diagnostic trouble code chart for the Supplemental Restraint System is (Scheme 47)as an example.

Scheme 47

PROBLEM SYMPTOMS TABLE

The suspected circuits or parts for each problem symptom are (Scheme 48) Use this table to troubleshoot the problem when a Normal code is displayed in the diagnostic trouble code chart but the problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts should be checked.

HINT

When the problem is not detected by the diagnostic system even though the problem symptom is present, it may be that the problem is occurring outside the detection range of the diagnostic system.

Scheme 48

CIRCUIT INSPECTION

How to read and use this information (Scheme 49).

Scheme 49

Scheme 50

Scheme 51

Scheme 52

Scheme 53

Scheme 54

1. RESISTANCE MEASURING CONDITION OF ELECTRONIC PARTS Unless stated, all resistance is measured at an ambient temperature of 20°C (68°F). As 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.
2. HANDLING OF CONNECTOR When removing the connector with lock, press the connector in the direction of the engagement and remove the lock by lightly pressing the lock claw. When removing the connector, do not hold the harness, but hold the connector. Before connecting the connector, check that there is no deformation, damage or missing terminals. The connector with a lock should be securely connected until it makes a "click" sound. When checking the connector with a Toyota electrical tester, check it from the backside (harness side) of the connector using a mini test lead. NOTE: As a water proof connector cannot be checked from the backside, check by connecting the sub-harness. Do not damage the terminals by moving the inserted tester needle.
3. 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 lightly pulling the wire harness (missing terminal, terminal crimping condition, core wire break). Check visually for is any rust, metal particles, water and bent terminals (rust, mixing of foreign object, terminal deformation). NOTE: When testing a gold-plated female terminal, always use a gold-plated male terminal. Checking of the contact pressure of the terminal: Prepare a spare male terminal. Insert it into a female terminal, check the engaged condition and sliding resistance.
4. REPAIR METHOD OF CONNECTOR TERMINAL If there is on the contact point, clean the contact point using an air gun or shop rag. However, never polish the contact point using sand paper as the platings may come off. In case of abnormal contact pressure, replace the female terminal. However, if a male terminal is gold-plated (gold color), use gold-plated female terminal and if it is silver-plated (silver color), use silver-plated female terminal.
5. HANDLING OF WIRE HARNESS When removing the wire harness, check the positioning of the wiring and clamping before starting work in order to be able to restore it correctly. Never twist, pull or loosen the wire harness more than necessary. Never allow the wire harness to come into contact with a high-temperature, rotating, moving, vibrating or sharp (edge of the panel, tip of the screw, etc.) part. When installing parts, never let the wire harness be interfered with. Never cut or break the cover of the wire harness. If one is cut or broken, replace it or securely repair it with electrical tape.

Scheme 55

Scheme 56

Scheme 57

Scheme 58

Scheme 59

Scheme 60

Scheme 61

Scheme 62

Scheme 63

1. 2. CHECK OPEN CIRCUIT For the open circuit in the wire harness in (Scheme 55), perform a continuity check in step (b) or a voltage check in step ( c ) to locate the Service Category. Check the continuity. Disconnect connectors A and C and measure the resistance between them. Resistance: 1 ohms or less HINT: Measure the resistance while lightly shaking the wire harness vertically and horizontally. In the case of (Scheme 56) Between terminal 1 of connector A and terminal 1 of connector C --> No continuity (open) Between terminal 2 of connector A and terminal 2 of connector C --> Continuity Therefore, the cause 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 57) Between terminal 1 of connector A and terminal 1 of connector B1 --> Continuity Between terminal 1 of connector B2 and terminal 1 of connector C --> No continuity (open) Therefore, the cause 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 by conducting a voltage check. (Scheme 58)with each connector still connected, measure the voltage between the body ground and terminal 1 of connector A at the ECU 5 V output terminal, terminal 1 of connector B, and terminal 1 of connector C, in that order. If the results are: 5 V: Between terminal 1 of connector A and body ground 5 V: Between terminal 1 of connector B and body ground 0 V: Between terminal 1 of connector C and body ground Therefore, the cause is an open circuit in the wire harness between terminal 1 of connector B and terminal 1 of connector C.
2. 3. CHECK SHORT CIRCUIT If the wire harness is ground shorted (Scheme 59)locate the Service Category by conducting a continuity check with the body ground in step (b). Check the continuity with the body ground. Disconnect connectors A and C and measure the resistance between terminals 1 and 2 of connector A and the body ground. Resistance: 10 kohms or higher HINT: Measure the resistance while lightly shaking the wire harness vertically and horizontally. In the case of (Scheme 60) Between terminal 1 of connector A and body ground --> Continuity (short) Between terminal 2 of connector A and body ground --> No continuity Therefore, the cause 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 the body ground, and terminal 1 of connector B2 and the body ground. In the case of (Scheme 61) Between terminal 1 of connector A and body ground --> No continuity Between terminal 1 of connector B2 and body ground --> Continuity (short) Therefore, the cause is a short circuit between terminal 1 of connector B2 and terminal 1 of connector C.
3. 4. CHECK AND REPLACE ECU NOTE: Start an inspection of the connector from the backside of the connector on the wire harness side with the connector connected to the ECU. When no measurement condition is specified, perform the inspection with the engine stopped and also the ignition switch ON. First check the ECU ground circuit. If it is faulty, repair it. If it is normal, the ECU could be faulty. In this case, replace the ECU with one that functions normally and check if the symptoms appear. Measure the resistance between the ECU ground terminal and body ground. Resistance: 1 ohms or less Disconnect the ECU connector, check the ground terminals on the ECU side and wire harness side for bends and check the contact pressure.