Diagnosis - A-650E: Diagnosis Lexus LS III

TROUBLE SHOOTING

Note. Any diagnosis should begin with confirming the customer's complaint. If possible, road test vehicle first, and note transmission performance for future reference during diagnosis.

PRELIMINARY INSPECTION

Transmission malfunctions may be caused by poor engine performance, improper adjustments or failure of hydraulic, mechanical or electronic components. Prior to diagnosing transmission concerns, always begin by checking fluid level, fluid condition and shift cable adjustment. Ensure engine starts with the gearshift lever in Park and Neutral to ensure proper adjustment of park/neutral position switch. Ensure all system-related fuses are okay. Check wire harnesses for proper routing. Verify all harness and component connections are clean and tight. See WIRING DIAGRAMS and CONNECTOR IDENTIFICATION . If area of fault cannot be located or repaired during preliminary inspection, check self-diagnostic system. See SELF-DIAGNOSTIC SYSTEM . Repair as necessary. If no DTCs are present, see MANUAL SHIFT TEST under PERFORMANCE TESTS.

Perform road test to determine if problem has been corrected. See ROAD TEST under PERFORMANCE TESTS. If problem still exists, diagnose by symptom. See SYMPTOM DIAGNOSIS .

SYMPTOM DIAGNOSIS

Note. Perform PRELIMINARY INSPECTION prior to diagnosing by symptom.

Note. Use the following symptoms to aid in preliminary diagnosis. If a listed symptom matches the customer's concern, check the applicable items for possible cause.

ROAD TEST

Test Procedure

Before road testing, note following information

1. No overdrive upshift or lock-up will occur when engine coolant is less than 140°F (60°C).
2. No 3rd upshift or lock-up will occur when engine coolant temperature is less than 140°F (60°C) and speed is less than 38 MPH.

"D/4" Range Test in NORM Or PWR Pattern Ranges

Note. Manufacturers shift speed specifications do not take into account posted local speed limits.

1. Shift transmission into "D" range. Hold accelerator pedal constant at full throttle position. Check 1-2, 2-3, 3-4 and 4-O/D upshift points. See «SHIFT SPEED SPECIFICATIONS»(ref-140961-S25391229282002070200000) .
2. Use procedure outlined in step 1 to check shock and slip between 1-2, 2-3, 3-4 and 4-O/D. Excessive shock can be caused by excessive line pressure, defective accumulator or defective check ball.
3. Run vehicle in O/D or lock-up in "D" range. Ensure lock-up and flex lock-up speeds are within specification. See «LOCK-UP SPEED SPECIFICATIONS»(ref-140961-S41970918542003010200000) and «FLEX LOCK-UP SPEED SPECIFICATIONS»(ref-140961-S39537316872003010200000) . Check for abnormal noise and vibration. Noise and vibration may be caused by unbalanced drive shaft, differential, torque converter or other drive train components.
4. While running in "D" range, 2nd, 3rd and O/D gears, check correct kickdown speed for 2-1, 3-2, 4-3 and O/D-4. Check for abnormal shock and slip at kickdown.
5. Check lock-up mechanism. Drive in O/D gear of "D" range, at steady speed (lock-up ON) of 40-43 MPH. Lightly depress accelerator pedal. Ensure engine RPM does not change abruptly. Large increase in engine RPM indicates there is no lock-up.

"3" Range Test

1. Shift to "3" range. Drive with accelerator pedal held constant at full throttle. Ensure 1-3 upshift points take place at correct speeds.
2. While driving in "3" range, release accelerator pedal and check engine braking. If there is no engine braking, 3rd coast brake is defective. Check for abnormal noise and shock at acceleration and deceleration.

"2/L" Range Test

While running in "L" range, ensure there is no upshift to 2nd gear. While running in "L" range, release accelerator pedal. If there is no engine braking effect, 1st and reverse brake is defective. Check for engine braking in "2" range. Note abnormal noise at acceleration and deceleration.

"R" Range Test

Shift into "R" range. Accelerate vehicle from a stop at full throttle. Ensure slipping does not occur.

"P" Range Test

Stop vehicle on 5 degree or more gradient. Shift transmission into "P" position. Release parking brake. Ensure parking pawl holds vehicle.

Stall Speed Test Procedure

Note. Stall speed test should be performed with transmission fluid temperature of 122-176°F (50-80°C).

1. Operate engine and transmission at normal operating temperature. Connect scan tool to DLC3, located under instrument panel. Apply parking brake and block front wheels.
2. Start engine, apply brake pedal and place transmission in "D" position. Accelerate engine to full throttle and note maximum RPM obtained. Repeat test in "R" position. Compare readings obtained to specification. See «STALL SPEED SPECIFICATIONS»(ref-140961-S26981020242001072700000) table.

Stall Test Results

Note. If stall RPM is more than 600 RPM less than specification, torque converter may be faulty.

1. If stall speed is the same for both ranges but lower than specification, engine output may be insufficient or stator one-way clutch may not be operating properly.
2. Stall speed exceeding specification in "D" range may be caused by a slipping forward clutch, defective No. 2 one-way clutch, overdrive one-way clutch or low main line pressure.
3. Stall speed exceeding specification in "R" range may be caused by a low main line pressure, direct clutch slipping, 1st and reverse brake slipping or defective overdrive one-way clutch.
4. Stall speeds exceeding specification in both ranges may be caused by a low main line pressure, improper fluid level or defective overdrive one-way clutch.

STALL SPEED SPECIFICATIONS

Main Line Pressure Test Results

Note. Manufacturer lists 0 PSI of line pressure when testing "R" position at idle speed for this model.

1. If line pressure in all ranges exceeds specification, check for defective regulator valve or defective SLT solenoid valve.
2. If line pressure is less than specification in all ranges, check for defective oil pump, defective regulator valve, defective SLT solenoid valve or defective O/D direct clutch.
3. If line pressure is less than specification in "D" range only, check for defective forward clutch or fluid leak in "D" range circuit.
4. If line pressure is low in "R" range only (except idle in Reverse), check for defective direct clutch, fluid leak in "R" range or defective 1st and reverse brake.

LINE PRESSURE SPECIFICATIONS

MANUAL SHIFT TEST

Note. Perform manual shift test if no trouble codes exist. Manual shift test determines if problem area is in electrical circuits or a mechanical transmission problem.

1. With ignition off, disconnect transmission solenoid connector. (Scheme 12) Road test vehicle and ensure transmission gear changes correspond with the gearshift lever position. See «GEAR APPLICATION»(ref-140961-S06263018192002061000000) table.
2. If abnormality exists, a mechanical transmission problem exists. Turn ignition off. Reconnect electrical connector. Clear trouble codes from ECM memory, as disconnecting electrical connector may set a trouble code. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-140961-S16684393182002061000000) under SELF-DIAGNOSTIC SYSTEM.

GEAR APPLICATION

Scheme 12

MALFUNCTION INDICATOR LIGHT INSPECTION

Note. The CHECK engine light located on instrument cluster is also known as Malfunction Indicator Light (MIL). Inspect MIL to ensure it is operational and will illuminate if a DTC is set.

1. Turn ignition on, engine off. MIL should illuminate and remain illuminated. If MIL does not illuminate, check bulb circuit on instrument cluster and circuit between MIL and ECM.
2. Start engine and ensure MIL goes off. If MIL remains on with engine running, a malfunction is detected. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-140961-S03273582642002061000000) .

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. DTCs may be retrieved using Lexus scan tool or an On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1987. Lexus scan tool or OBD-II scan tool may be operated in NORMAL mode when retrieving DTCs. Only Lexus scan tool may be used in CHECK mode when retrieving DTCs.

NORMAL mode is used to retrieve DTCs from ECM. CHECK mode is used to check for DTCs when operating vehicle to simulate conditions in which DTC was set. CHECK mode contains a higher sensing ability to detect malfunctions. CHECK mode helps determine malfunctions caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when ignition is turned from ON to ACC or OFF position or scan tool is switched from NORMAL mode to CHECK mode, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

CLEARING DIAGNOSTIC TROUBLE CODES

Note. If using Lexus scan tool, DTCs and freeze-frame data may be cleared by switching from CHECK mode to NORMAL mode, or from NORMAL mode to CHECK mode.

1. After performing repairs, clear ECM memory of all stored DTCs and freeze-frame data. DTCs and freeze-frame data may be cleared by using scan tool and scan tool manufacturer's instructions.
2. DTCs and freeze-frame data may also be cleared by removing EFI fuse from junction block located in engine compartment. DTCs and freeze-frame data may also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, alarm, seats, etc.) will be cancelled and must be reset.

DLC3 Inspection

1. If scan tool displays UNABLE TO CONNECT TO VEHICLE when scan tool is connected, try scan tool on another vehicle. If scan tool operates on another vehicle, go to next step. If scan tool does not operate on another vehicle, problem is probably with scan tool.
2. Check DLC3 for loose or damaged terminals. Ensure DLC3 terminals are in correct position in connector. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Repair as necessary. If connector and terminals are okay, go to next step.
3. Check voltage and resistance between ground and specified terminal on DLC3. See «DLC3 VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-140961-S35644110612002061000000) table. see scheme 23 If voltage and resistance readings are not as specified, check circuit in question.

DLC3 VOLTAGE & RESISTANCE SPECIFICATIONS

DIAGNOSTIC TESTS

Note. When trouble shooting transmission, first check for stored DTCs and repair as necessary. If no DTCs exist, perform MANUAL SHIFT TEST to determine if problem area is in electrical circuits or a mechanical transmission problem.

Diagnostic Procedure

1. Connect scan tool to DLC3. see scheme 12 Start engine. Drive vehicle and note vehicle speed on scan tool. If vehicle speed matches scan tool speed value, go to next step. If vehicle speed does not match scan tool speed value, replace ECM and retest system.
2. Check speedometer operation. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If speedometer is operating properly, go to next step. If speedometer is not operating properly. Repair or replace speedometer circuit.
3. Disconnect appropriate ECM harness connector. Using an ohmmeter, measure resistance between circuit SP2+ and SP2- on ECM harness connector. see scheme 30- see scheme 37. If resistance is 560-680 ohms, replace ECM and retest system. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If resistance is not 560-680 ohms, go to next step.
4. Remove VSS from rear of transmission. Using an ohmmeter, measure resistance between VSS connector terminals. Resistance should be 560-680 ohms at 68°F (20°C). Using voltmeter, set meter to AC voltage. Measure voltage between VSS connector terminals. Place a magnet close to front of VSS and then quickly remove magnet (to generate a voltage pulse). (Scheme 13) If voltage pulse is not generated, replace VSS and retest. If voltage pulse is generated, check for short or open circuit in wiring harness between VSS and ECM. See «WIRING DIAGRAMS»(ref-140961-S18779056922002061000000). If problem was not found, repair or replace wiring harness as necessary. If okay, go to next step.
5. Check and repair the internal transmission malfunction. See appropriate OVERHAUL article.

Scheme 13

1. Connect scan tool to DLC3. see scheme 12 Start engine. Drive vehicle and note vehicle speed on scan tool. If vehicle speed matches scan tool speed value, go to next step. If vehicle speed does not match scan tool speed value, replace ECM and retest system. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
2. Remove speed sensor (O/D direct clutch) from transmission. see scheme 8 Using an ohmmeter, measure resistance between sensor terminals. Resistance should be 560-680 ohms at 68°F (20°C). If not within specification, replace speed sensor. If within specification, go to next step.
3. Install the speed sensor (O/D direct clutch) into the transmission. Disconnect ECM harness connector E3. Using an ohmmeter, measure resistance between circuit SP2+ and SP2- on ECM harness connector. see scheme 38and see scheme 39. If resistance is 560-680 ohms, replace ECM and retest system. If resistance is not 560-680 ohms, check for short or open circuit in wiring harness between VSS and ECM. Repair or replace wiring harness as necessary.

1. Raise and support vehicle. Disconnect transmission solenoid connector. (Scheme 12) Remove oil pan. See LUBRICATION in appropriate SERVICING article. Remove harness and sensor assembly. Connect ohmmeter leads between terminals No. 1 and 7. (Scheme 14)
2. Submerge sensor in water. Heat water while measuring sensor resistance. See «ATF TEMPERATURE SENSOR RESISTANCE»(ref-140961-S23143610722002061000000) table. If resistance is not as specified, replace sensor. If resistance is as specified, inspect and repair wiring harness circuits between sensor and ECM. If circuits are okay, replace ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION.

ATF TEMPERATURE SENSOR RESISTANCE

Scheme 14

Circuit Description

DTC will set if after 12 seconds of the engine start, the temperature of the atmosphere and that of the engine coolant is more than 14°F (-10°C) and after normal driving for over 20 minutes and 6.2 miles, the ATF temperature is less than 14°F (10°C). Possible causes

1. Open in ATF temperature sensor circuit.
2. ATF temperature sensor malfunction.
3. ECM malfunction.

Are there any DTCs being set? If so, go to that DTC and diagnose first. If not, repair or replace transmission wiring harness and connectors.

1. Install scan tool to DLC3. Turn the ignition to the ON position. Turn the scan tool ON. Using the scan tool, read the O/D direct clutch speed with engine idling. If scan tool reads 650-750 RPM (700-800 RPM on LS 430), check for an intermittent condition, poor connection, corroded terminals or cut/broken wiring. If no problem was found, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If reading was not 650-750 RPM (700-800 RPM on LS 430), go to next step.
2. Remove O/D direct clutch speed sensor from transmission. Measure resistance between sensor terminals. Resistance should be 560-680 ohms at 68°F (20°C). If resistance is not as specified, replace sensor. Check voltage between sensor terminals, while a magnet is placed close to the sensor and then quickly taken away. (Scheme 13) The voltage should be extremely low. If reading is not as specified, replace the direct clutch speed sensor. If readings was within specification, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION.

1. Install scan tool to DLC3. Turn the ignition to the ON position. Turn the scan tool ON. Using the scan tool, read the O/D direct clutch speed with engine idling. If scan tool reads 650-750 RPM, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If reading was not 650-750 RPM, go to next step.
2. Remove O/D direct clutch speed sensor from transmission. see scheme 6 Measure resistance between sensor terminals. Resistance should be 560-680 ohms at 68°F (20°C). If resistance is not as specified, replace sensor. If resistance is as specified, check voltage between sensor terminals when a magnet is put close to tip of speed sensor. (Scheme 13) If a low intermittent voltage is generated, sensor is okay. If no voltage is found, replace speed sensor. If okay, go to next step.
3. Disconnect the appropriate ECM harness connector and measure the resistance between terminals NC0+ and NC0- on ECM harness connector. If resistance is between 560-680 ohms, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If resistance is not as specified, repair or replace the wiring harness and connector.

1. Remove O/D direct clutch speed sensor (NC0) from transmission. see scheme 8 Measure resistance between sensor terminals. Resistance should be 560-680 ohms at 68°F (20°C). If resistance is not as specified, replace sensor. If sensor tests okay, go to next step.
2. Install the speed sensor (NC0) into transmission. Disconnect the appropriate ECM harness connector and measure the resistance between terminals NC0+ and NC0- on ECM harness. If resistance is between 560-680 ohms, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If resistance is not as specified, repair or replace the wiring harness and connector.

Remove and inspect operation of solenoids. See NO. 1, NO. 2, NO. 3 & NO. 4 SOLENOIDS under COMPONENT TESTS. If solenoids are okay, inspect valve body. See appropriate OVERHAUL article.

1. Ensure ignition is off. Access ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. Disconnect appropriate ECM harness connector. Using ohmmeter, measure resistance between ground and terminals S1, S2 and/or S3 on ECM harness connector. See «PIN VOLTAGE TESTS»(ref-140961-S21899035932002070200000). If resistance is 11-15 ohms at 68°F (20°C), replace ECM and retest. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If resistance is not within specification, go to next step.
2. Disconnect transmission solenoid harness connector. (Scheme 12) Check continuity between terminal S1, S2 and/or S3 on transmission harness connector and corresponding terminal of ECM. see scheme 22 If continuity exists for all circuits, go to next step. If continuity does not exist for any circuit, inspect and repair circuit(s) as necessary.
3. Remove and inspect operation of solenoids. See «NO. 1, NO. 2, NO. 3 & NO. 4 SOLENOIDS»(ref-140961-S22073889132002061000000) under COMPONENT TESTS. If solenoid(s) are okay, inspect internal solenoid transmission harness and connector. Replace internal transmission harness and connector as necessary.

1. Ensure ignition is off. Access ECM. Disconnect appropriate ECM harness connector. See «PIN VOLTAGE TESTS»(ref-140961-S21899035932002070200000). Using ohmmeter, measure resistance between ground and terminal S4 on ECM harness connector. If resistance is 11-15 ohms, replace ECM and retest. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If resistance is not within specification, go to next step.
2. Disconnect transmission solenoid harness connector. (Scheme 12) Check continuity between terminal S4 on transmission harness connector and corresponding terminal at ECM. see scheme 22 If continuity exists for all circuits, go to next step. If continuity does not exist for any circuit, inspect and repair circuit(s) as necessary.
3. Remove and inspect operation of solenoids. See «NO. 1, NO. 2, NO. 3 & NO. 4 SOLENOIDS»(ref-140961-S22073889132002061000000) under COMPONENT TESTS. If solenoid(s) are okay, inspect internal solenoid transmission harness and connector. Replace internal transmission harness and connector as necessary.

Note. If not using a Lexus hand held tester start diagnosis at step 2 .

1. Connect the Lexus scan tool to DLC3. Turn the ignition to the ON position. Using the ACTIVE TEST, check the LOCK-SHIFT operation. If check reads LOCK-UP ON, go to next step. If not, replace torque converter clutch. See appropriate OVERHAUL article.
2. Disconnect transmission solenoid harness connector. (Scheme 12) Using ohmmeter, measure resistance between terminals SLU+ and SLU- on transmission component connector. see scheme 22 If resistance is 5.0-5.6 ohms at 68°F (20°C), go to next step. If resistance is not 5.0-5.6 ohms at 68°F (20°C), replace SLU solenoid.
3. Raise and support vehicle. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. Remove SLU solenoid. see scheme 3 Connect a jumper wire between battery voltage and SLU solenoid terminal No. 1. Connect another jumper wire between ground terminal and terminal No. 2. (Scheme 15)
4. Solenoid plunger should move away from solenoid electrical connector. Remove jumper wire from solenoid terminal No. 2. Solenoid plunger should move back toward solenoid electrical connector. If solenoid plunger responds properly, go to next step. If solenoid plunger does not respond, replace SLU solenoid and retest.
5. If solenoid plunger responds properly, check and repair valve body as necessary. See appropriate OVERHAUL article.

Scheme 15

Note. If not using a Lexus hand held tester start diagnosis at step 2 .

1. Connect the Lexus scan tool to DLC3. Turn the ignition to the ON position. Using the ACTIVE TEST, check the LOCK-SHIFT operation. If check reads LOCK-UP ON, go to next step. If not, replace torque converter clutch. See appropriate OVERHAUL article.
2. Raise and support vehicle. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. Remove SLU solenoid. see scheme 3 Connect a jumper wire between battery voltage and SLU solenoid terminal No. 1. Connect another jumper wire between ground and terminal No. 2. (Scheme 15) Solenoid plunger should move back toward solenoid electrical connector. Remove jumper wire from solenoid terminal No. 2. Solenoid plunger should move away from solenoid electrical connector. Disconnect transmission solenoid harness connector. If solenoid plunger responds properly, go to next step. If solenoid plunger does not respond, replace SLU solenoid and retest.
3. Check valve body operation. See appropriate OVERHAUL article. If okay, replace TCC.

Note. If not using a Lexus hand held tester start diagnosis at step 2 .

1. Connect the Lexus scan tool to DLC3. Turn the ignition to the ON position. Using the ACTIVE TEST, check the LOCK-SHIFT operation. If check reads LOCK-UP ON, go to next step. If not, replace torque converter clutch. See appropriate OVERHAUL article.
2. Raise and support vehicle. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. Remove SLU solenoid. see scheme 3 Connect a jumper wire between battery voltage and SLU solenoid terminal No. 1. Connect another jumper wire between ground and terminal No. 2. (Scheme 15) Solenoid plunger should move back toward solenoid electrical connector. Remove jumper wire from solenoid terminal No. 2. Solenoid plunger should move away from solenoid electrical connector. Disconnect transmission solenoid harness connector. If solenoid plunger does not respond, replace SLU solenoid and retest. If solenoid plunger responds properly, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION.

1. Check stoplights. If stoplights do not function properly, repair as necessary and retest system. If stoplights function properly, go to next step.
2. Turn ignition on. Backprobing, measure voltage between ground and terminal STP at ECM harness connector. See «PIN VOLTAGE TESTS»(ref-140961-S21899035932002070200000) . With brake pedal depressed, voltage should be 7.5-14.0 volts. With brake pedal released, voltage should be less than 1.5 volt. If voltage is not as specified, go to next step. If voltage is as specified, check wiring harness and connectors for an intermittent condition, poor connections, corroded terminals or cut/broken wiring.
3. Disconnect the appropriate ECM harness connector containing circuit STP. Check the continuity between circuit STP of the ECM and the stop light switch. If continuity is present, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If no continuity is present, check wiring harness and connectors for an intermittent condition, poor connections, corroded terminals or cut/broken wiring.

1. Disconnect transmission solenoid harness connector. (Scheme 12) Using ohmmeter, measure resistance between terminals SLU+ and SLU- on transmission component connector. see scheme 22 If resistance is 5.0-5.6 ohms at 68°F (20°C), replace ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If resistance is not 5.0-5.6 ohms at 68°F (20°C), go to next step.
2. Raise and support vehicle. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. see scheme 3 Using ohmmeter, measure resistance between solenoid connector terminals. If resistance is 5.0-5.6 ohms at 68°F (20°C), replace transmission harness and connector. If resistance is not 5.0-5.6 ohms at 68°F (20°C), replace solenoid.

1. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. Using ohmmeter, measure resistance between SLT terminals. Resistance should be 5.0-5.6 ohms at 68°F (20°C). Remove SLT solenoid. see scheme 3 Connect a jumper wire with an 8-10-watt bulb in series between battery voltage and SLT solenoid terminal No. 1. Connect another jumper wire between ground and terminal No. 2. (Scheme 15) Solenoid plunger should move away from solenoid electrical connector. Remove jumper wire from solenoid terminal No. 2. Solenoid plunger should move back toward solenoid electrical connector. If solenoid plunger does not respond, or resistance was not as specified, replace SLT solenoid and retest. If solenoid plunger responds properly, or resistance is as specified, go to next step.
2. Check transmission wiring harness and connector for an intermittent condition, poor connections, corroded terminals or cut/broken wiring. Replace as necessary. If wiring is okay, replace ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION.

1. Raise and support vehicle. Disconnect transmission solenoid harness connector. (Scheme 12) Using ohmmeter, measure resistance between terminals SLT+ and SLT- on transmission component connector. see scheme 22 If resistance is 5.0-5.6 ohms at 68°F (20°C), go to next step. If resistance is not 5.0-5.6 ohms at 68°F (20°C), go to step 3.
2. Connect the transmission solenoid harness connector. Disconnect the ECM wiring harness connector. Measure resistance between terminals SLT+ and SLT- of ECM. If the resistance is between 5.0 and 5.6 ohms at 68°F (20°C), replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If not, repair or replace transmission wiring harness.
3. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. Using ohmmeter, measure resistance between terminals on SLT solenoid. Resistance should be 5.0-5.6 ohms at 68°F (20°C). Remove SLT solenoid. see scheme 3 Connect a jumper wire with an 8-10-watt bulb in series between battery voltage and SLT solenoid terminal No. 1. Connect another jumper wire between ground and terminal No. 2. (Scheme 15) Solenoid plunger should move away from solenoid electrical connector. Remove jumper wire from solenoid terminal No. 2. Solenoid plunger should move back toward solenoid electrical connector. If solenoid plunger does not respond, or resistance was not as specified, replace SLT solenoid and retest. If solenoid plunger responds properly, or resistance is as specified, inspect transmission harness and connector. Repair or replace as necessary.

1. Disconnect transmission solenoid harness connector. (Scheme 12) Using ohmmeter, measure resistance between terminals SLN+ and SLN- on transmission component connector. see scheme 22 If resistance is 5.0-5.6 ohms at 68°F (20°C), go to next step. If resistance is not 5.0-5.6 ohms at 68°F (20°C), replace SLN solenoid.
2. Raise and support vehicle. Remove transmission oil pan. See LUBRICATION in appropriate SERVICING article. Disconnect solenoid connector. Remove SLN solenoid. see scheme 3 Connect a jumper wire with an 8-10-watt bulb in series between battery voltage and SLN solenoid terminal No. 1. Connect another jumper wire between ground and terminal No. 2. (Scheme 15)
3. Solenoid plunger should move away from solenoid electrical connector. Remove jumper wire from solenoid terminal No. 2. Solenoid plunger should move back toward solenoid electrical connector. If solenoid plunger does not respond, replace SLN solenoid and retest. If solenoid plunger responds properly, inspect transmission harness and connector. Repair as necessary. If transmission harness and connector is okay, replace ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION.

Note. If not using a Lexus hand held tester start diagnosis at step 2 .

1. Install the scan tool to DLC3. Check the PNP switch readout on the scan tool, while moving the gearshift lever through all gear positions. If all the readings from the scan tool correspond to actual gearshift lever positions, replace the ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If not, go to step 3.
2. Turn ignition off. Access ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. Turn ignition on. Using DVOM, measure voltage at terminals "P", "R", "N", "D", "4", "3", "2" and "L" at appropriate ECM harness connector or check harness between terminal and body ground with the gearshift lever in each shift position. Specification is battery voltage. (Scheme 16) If voltages measured are within specifications, replace ECM. See «ENGINE CONTROL MODULE»(ref-140961-S24794014572002061000000) under REMOVAL & INSTALLATION. If any voltage measurement is not within specification, go to next step.
3. Check park/neutral position switch. See «PARK/NEUTRAL POSITION SWITCH»(ref-140961-S09006987912002061000000) under COMPONENT TESTS. Replace as necessary. If switch is okay, check and repair circuit(s) between PNP switch and ECM. See «WIRING DIAGRAMS»(ref-140961-S18779056922002061000000).

Scheme 16