Electronic Controlled Automatic Transaxle (ECT) - Diagnosis: Diagnosis Lexus RX II

HOW TO PROCEED WITH TROUBLESHOOTING

The hand-held tester can be used at steps 3, 4, 6, 9.

HINT

The ECM of this system is connected to the multiplex communication system. Therefore, before starting troubleshooting, make sure to check that there is no trouble in the multiplex communication system.

1. Vehicle Brought to Workshop
2. Customer Problem Analysis (See «CUSTOMER PROBLEM ANALYSIS CHECK»(ref-209546-S15927502072005121000000) )
3. Connect the OBD II scan tool or hand-held tester to DLC3
4. Check and Clear DTC and Freeze Frame Data (See «PRE-CHECK»(ref-209546-S20309540412005121000000) )
5. Visual Inspection
6. Setting the Check Mode Diagnosis (See «PRE-CHECK»(ref-209546-S20309540412005121000000) )
7. Problem Symptom Confirmation Symptom does not occur: Go to step 8 Symptom occurs: Go to step 9
8. Symptom Simulation (See «SYMPTOM SIMULATION»(ref-215923-S02520245562006011900000) )
9. DTC Check (See «PRE-CHECK»(ref-209546-S20309540412005121000000) ) DTC is not output: Go to step 10 DTC is output: Go to step 17
10. Basic Inspection (See «AUTOMATIC TRANSAXLE FLUID (ATM)»(ref-209590-S18952365822005121000000) , «ADJUSTMENT»(ref-209590-S22830665072005121000000) and «ADJUSTMENT»(ref-209590-S40614849362005121000000) ) OK: GO TO NEXT STEP. NG: Go to step 19
11. Mechanical System Test (See «PRE-CHECK»(ref-209546-S20309540412005121000000) ) OK: GO TO NEXT STEP. NG: Go to step 16
12. Manual Shifting Test (See «PRE-CHECK»(ref-209546-S20309540412005121000000) ) OK: GO TO NEXT STEP. NG: Go to step 14
13. Problem Symptoms Table Chapter 1 (See «PROBLEM SYMPTOMS TABLE»(ref-209546-S11825380642005121000000) ) OK: GO TO NEXT STEP. NG: Go to step 18
14. Problem Symptoms Table Chapter 2 (See «PROBLEM SYMPTOMS TABLE»(ref-209546-S11825380642005121000000) ) OK: GO TO NEXT STEP. NG: Go to step 16
15. Problem Symptoms Table Chapter 3 (See «PROBLEM SYMPTOMS TABLE»(ref-209546-S11825380642005121000000) ) NG: GO TO NEXT STEP.
16. Part Inspection Go to step 19
17. DTC Chart (See «DIAGNOSTIC TROUBLE CODE CHART»(ref-209546-S16740145342005121000000) )
18. Circuit Inspection (See CIRCUIT INSPECTION under appropriate DTC test procedure )
19. Identification of Problem
20. Repair
21. Confirmation Test End

DIAGNOSTIC TROUBLE CODE TABLE

If a DTC is displayed during the DTC check, check the circuit listed in the table below and proceed to the trouble area.

DIAGNOSTIC TROUBLE CODE

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1. ECM HINT: *1: Shift lever with Multi-mode automatic transmission type *2: Except *1 (Gate shift lever type) Pulse generation 1 Reference: Pulse generation 2 Reference: Pulse generation 3 Reference: Pulse generation 4 Reference: Pulse generation 5 Reference: Pulse generation 6 Reference: Pulse generation 7 Reference: Pulse generation 8 Reference
2. Instrument Panel Junction Block Assy (Multiplex Network Body ECU)

PROBLEM SYMPTOMS TABLE

HINT

If a normal code is displayed during the diagnostic trouble code check although the trouble still occurs, check the electrical circuits for each symptom in the order given in the charts on the following pages and proceed to the page given for troubleshooting.

The Matrix Chart is divided into 3 chapters.

1. If the instruction "Proceed to next circuit inspection shown on matrix chart" is given in the flow chart of each circuit, proceed to the circuit with the next highest number in the table to continue the check.
2. If the trouble still occurs even though there are no abnormalities in any of the other circuits, check and replace the ECM.

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Scheme 272

1. Chapter 1: Electronic Circuit Matrix Chart HINT: *1: When the circuit on which mark *1 is attached is a malfunction, DTC could be output (See «PRE-CHECK»(ref-209546-S20309540412005121000000) ). *2: Gate shift lever type *3: Shift lever with Multi-mode automatic transmission type
2. Chapter 2: On-Vehicle Repair See appropriate AUTOMATIC TRANSMISSION OVERHAUL article.
3. Chapter 3: Off-Vehicle Repair See appropriate AUTOMATIC TRANSMISSION OVERHAUL article.

CIRCUIT DESCRIPTION

The park/neutral position switch detects the shift lever position and sends signals to the ECM.

Scheme 273

HINT

*1: Gate shift lever type

*2: Shift lever with Multi-mode automatic transmission type

The ATF temperature sensor converts the fluid temperature into a resistance value which is input into the ECM.

Scheme 274

The ATF temperature sensor converts the fluid temperature into a resistance value which is input into the ECM.

Scheme 275

This sensor detects the rotation speed of the input turbine. By comparing the input turbine speed signal (NT) with the counter gear speed sensor signal (NC), the ECM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions. Thus, providing smooth gear shift.

Scheme 276

The purpose of this circuit is to prevent the engine from stalling while driving in lock-up condition, when brakes are suddenly applied.

When the brake pedal is depressed, this switch sends a signal to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.

Scheme 277

Shifting from 1st to 5th is performed in combination with "ON" and "OFF" operation of the shift solenoid valves SL1, SL2, SL3, S4 and SR which is controlled by the ECM. If an open or short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be operated smoothly (Fail safe function).

Scheme 278

Fail safe function

If either of the shift solenoid valve circuits develops an open or short, the ECM turns the other shift solenoid "ON" and "OFF" in order to shift into the gear positions shown in the table below.

Manual shifting as shown in the following table must be done (In case of a short circuit, the ECM stops sending the current to the short circuit solenoid).

Scheme 279

See DTC P0748 PRESSURE CONTROL SOLENOID "A" ELECTRICAL (SHIFT SOLENOID VALVE SL1) .

Scheme 280

This sensor detects the rotation speed of the counter gear. By comparing the counter gear speed signal (NC) with the direct clutch speed sensor signal (NT), the ECM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions. Thus smooth gear shifting is performed.

Scheme 281

See DTC P0748 PRESSURE CONTROL SOLENOID "A" ELECTRICAL (SHIFT SOLENOID VALVE SL1) .

Scheme 282

See DTC P0748 PRESSURE CONTROL SOLENOID "A" ELECTRICAL (SHIFT SOLENOID VALVE SL1) .

Scheme 283

See DTC P0748 PRESSURE CONTROL SOLENOID "A" ELECTRICAL (SHIFT SOLENOID VALVE SL1) .

Scheme 284

The throttle pressure that is applied to the primary regulator valve (which modulates the line pressure) causes the solenoid valve SLT, under electronic control, to precisely and minutely modulate and generate the line pressure according the extent of the accelerator pedal depressed or the output of engine power.

Scheme 285

This controls the line pressure and provides smooth shifting. Upon receiving a signal of the throttle valve opening angle, the ECM controls the line pressure by sending a predetermined (*) duty ratio to the solenoid valve, modulating the line pressure and generating throttle pressure.

(*): Duty Ratio

The duty ratio is the ratio of the period of continuity in one cycle, For example, if A is the period of continuity in one cycle, and B is the period of non-continuity, then Duty Ratio = A (A+B) x 100 (%)

Scheme 286

Scheme 287

The shift solenoid valve DSL is turned "ON" and "OFF" by signals from the ECM in order to control the hydraulic pressure operation, the lock-up relay valve, which then the controls operation of the lock-up clutch.

Scheme 288

Fail safe function

If the ECM detects a malfunction, it turns the shift solenoid valve DSL OFF.

When shifting the shift lever into S position using the transmission control switch, it is possible to shift in 1 to 5 positions.

Shifting "+" once changes up 1 shift range position, "-" once changes down 1 shift range position respectively.

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1. CHECK HARNESS AND CONNECTOR (BATTERY-TRANSMISSION CONTROL SWITCH) Disconnect the transmission control switch connector of shift lock control unit assy. Measure the voltage according to the value(s) in the table below. Standard: OK: GO TO NEXT STEP. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-215923-S29911983652006011900000) )
2. CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH-BODY GROUND) Measure the resistance according to the value(s) in the table below. Standard: OK: GO TO NEXT STEP. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-215923-S29911983652006011900000) )
3. INSPECT SHIFT LOCK CONTROL UNIT ASSY Measure resistance between each terminal of shift lock control unit assy when the shift lever is moved to each position. Standard: OK: GO TO NEXT STEP. NG: REPLACE SHIFT LOCK CONTROL UNIT ASSY (See «SHIFT LEVER ASSY (ATM)»(ref-209590-S14774750982005121000000) )
4. CHECK HARNESS AND CONNECTOR (TRANSMISSION CONTROL SWITCH-ECM) Connect the transmission control switch connector of shift lock control unit assy. Turn the ignition switch to the ON position, and measure the voltage according to the value(s) in the table below when the shift lever is moved to each position. Standard: Turn the ignition switch to the LOCK position. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below when the shift lever is moved to each position. Standard: OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE (See «PROBLEM SYMPTOMS TABLE»(ref-209546-S11825380642005121000000) ) NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-215923-S29911983652006011900000) )

ECT SNOW is the system that operates the throttle motor to control engine output to reduce skidding of the driving wheels, guarantee takeoff acceleration, driving straightness and turning stability.

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1. DRIVING TEST Start the engine. Turn the ECT SNOW switch "OFF" (Normal drive mode). Confirm vehicle response by driving from a parked position to fully depressing the accelerator pedal. Turn the ECT SNOW switch "ON" and perform the same check as (c). Confirm that there is a difference between ECT SNOW switch "ON" and "OFF". HINT: Driving test should be done on a paved road (a nonskid road). Make sure not to use the TRAC system when testing a vehicle equipped with one. Standard: There is a difference in acceleration between "ON" and "OFF". OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE (See «PROBLEM SYMPTOMS TABLE»(ref-209546-S11825380642005121000000) ) NG: Go to step 2
2. CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSY NO. 1 - BODY GROUND) Disconnect the connector of pattern select switch (EC SNOW switch). Measure the resistance according to the value(s) in the table below. Standard: OK: GO TO NEXT STEP. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-215923-S29911983652006011900000) )
3. INSPECT PATTERN SELECT SWITCH ASSY NO. 1 Measure the resistance according to the value(s) in the table below. Standard: OK: GO TO NEXT STEP. NG: REPLACE PATTERN SELECT SWITCH ASSY NO. 1
4. CHECK HARNESS AND CONNECTOR (PATTERN SELECT SWITCH ASSY NO. 1 - MULTIPLEX NETWORK BODY ECU) Connect the connector of pattern select switch (ECT SNOW switch). Disconnect the instrument panel junction block assy (multiplex network body ECU) connector. Measure the resistance between terminals SNOW of Instrument panel junction block assy (multiplex network body ECU) and body ground. Standard: OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE (See «PROBLEM SYMPTOMS TABLE»(ref-209546-S11825380642005121000000) ) NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-215923-S29911983652006011900000) )