INTRODUCTION
If no faults were found while performing BASIC TESTING , proceed with self-diagnostics. If no fault codes or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
HARD FAILURES
Hard failures cause malfunction light to glow and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle runs but driveability will not be optimum.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker or glow and go out after intermittent fault goes away. Corresponding trouble code will be retained in ECU memory (except for Codes 16, 17, 18, 43, 51 and 53). Codes 16, 17, 18, 43, 51 and 53 do not illuminate CHECK ENGINE light and are output only during test procedures. See appropriate diagnostic code chart.
Codes must be erased from memory after repair has been made. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
Scheme 7
Scheme 8
Scheme 9
- Normal mode is used for routine testing of vehicle. To read diagnostic codes, ensure battery voltage is at least 11 volts, throttle valve is fully closed, transaxle/transmission is in Neutral and all accessories are off.
- Total Diagnostic Communication Link (TDCL) connector is located under left side of instrument panel. (Scheme 7) Diagnostic codes can be obtained through TDCL connector or check connector. On ES300, check connector is located in engine compartment near right shock tower. On SC300, check connector is located in engine compartment on top of exhaust manifold. (Scheme 8)
- On all models, turn ignition on. DO NOT start engine. Using a jumper wire, connect terminals E1 and TE1 together either on TDCL connector or check connector. (Scheme 9) Count number of flashes from CHECK ENGINE light.
- If CHECK ENGINE light flashes 2 times every second, system is normal. If a diagnostic code is displayed, first group of flashes will indicate first digit of a 2-digit diagnostic code. After a 1.5 second delay, second group of flashes will indicate second digit of diagnostic code.
- If more than one code is stored, a 2.5 second delay will occur between diagnostic codes. After all diagnostic codes have been displayed, a 4.5 second delay will occur and then codes will be repeated until jumper wire connecting terminals E1 and TE1 is disconnected. Diagnostic codes will display from smallest to largest number.
- Record diagnostic codes. See «CODE IDENTIFICATION»(/lexus/es/xv10-1991-1994/remont/testing-diagnostics/#engine-controls-tests-wcodes) table under TROUBLE CODE DEFINITION for description of possible circuit problem. After reading diagnostic code description, see appropriate diagnostic code chart. To clear codes, see CLEARING CODES.
Test Mode
- This mode detects same malfunctions as normal mode. It also detects malfunctions in starter signal circuit, No. 1 and No. 2 cam position sensors (if equipped), idle contact signal of TPS, A/C signal and neutral start switch signal. Test mode is more sensitive to intermittent and regular faults and is used for road test conditions.
- To read diagnostic codes, ensure battery voltage is at least 11 volts, throttle valve is fully closed, transmission is in Neutral and all accessories are off. Total Diagnostic Communication Link (TDCL) connector is located under left side of instrument panel. (Scheme 7)
- Turn ignition off. Using a jumper wire, connect terminals E1 and TE2 together on TDCL connector. (Scheme 9) Turn ignition on. DO NOT start engine. NOTE: If terminals E1 and TE2 are connected after ignition is turned on, test mode will not start.
- When ignition is turned on, CHECK ENGINE light on instrument panel should flash. If CHECK ENGINE light does not flash, see COMPUTERIZED ENGINE CONTROLS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
- Start engine. Perform road test and simulate conditions described by customer. DO NOT disconnect jumper wire connecting terminals E1 and TE2. After road test, connect terminals E1 and TE1 together on TDCL connector using a jumper wire.
- Count number of flashes from CHECK ENGINE light. System is normal if CHECK ENGINE light flashes 2 times every second. If a diagnostic code is displayed, first group of flashes will indicate first digit of a 2-digit diagnostic code. After a 1.5 second delay, second group of flashes will indicate second digit of diagnostic code.
- If more than one code is stored, a 2.5 second delay will occur between diagnostic codes. After all diagnostic codes have been displayed, a 4.5 second delay will occur and then codes will be repeated until jumper wire connecting terminals E1 and TE1 is disconnected. Diagnostic codes will display from smallest to largest number.
- After completing check, disconnect terminals TE1 and TE2 from terminal E1 on TDCL connector. Diagnostic Codes 17, 18 and 43 will set if engine is not cranked when entering test mode. This is normal. When vehicle speed is less than 3 MPH, Code 42 will set (ES300). This is normal. If automatic transmission is in "D", 2, "L" or "R", A/C switch is in ON position or accelerator pedal is depressed, Code 51 will set. This is normal.
- Record diagnostic codes. See appropriate «CODE IDENTIFICATION»(/lexus/es/xv10-1991-1994/remont/testing-diagnostics/#engine-controls-tests-wcodes) table under TROUBLE CODE DEFINITION for description of diagnostic code and possible problem with circuit. After reading description of diagnostic code, see appropriate diagnostic code chart. To clear codes, see CLEARING CODES.
Momentary Interruption Test
If Code 13, 22, 24, 41 or 47 is stored in ECU memory during diagnosis and no trouble can be found with these circuits, perform MOMENTARY INTERRUPTION TEST.
- Clear codes from ECU memory. See CLEARING CODES. With ignition off, connect a jumper wire between terminals E1 and TE2 of TDCL connector.
- Start engine. Ensure CHECK ENGINE light goes out. Pull lightly on wires, and apply vibration to connectors and relays associated with diagnostic codes.
- If CHECK ENGINE light glows during this test, a fault is in indicated connector or location in wiring harness. Repair as necessary.
- Clear diagnostic codes. Start engine. If CHECK ENGINE light does not go out, check thoroughly for faulty connections. Perform MOMENTARY INTERRUPTION TEST again. If CHECK ENGINE light still will not go out, see CONTROL UNIT under COMPUTERIZED ENGINE CONTROLS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
Note. Electronically Controlled Transaxle/Transmission (ECT) uses same ECU as EFI system. This article only covers Engine Performance related testing.
TROUBLE CODE DEFINITION
| Code (2) | Fault | Circuit |
|---|---|---|
| 12 | No Distributor Signal After 2 Seconds Cranking | RPM Signal |
| 13 | No Distributor Signal At More Than 1000 RPM | RPM Signal |
| 14 | No IGF Signal For 6 IGT Signals | Ignition |
| 16 | No Link Between CPU & ECT CPU | (3) ECT Control |
| 21 | Fixed Oxygen Sensor Voltage | Main Oxygen Sensor (Left Bank ES300, Front Side SC300) |
| 22 | Open Or Short In Circuit For More Than .5 Second | Water Temperature Sensor |
| 24 | Open Or Short In Circuit For More Than .5 Second | Intake Air Temperature Sensor |
| 25 | Sensor Voltage Low For More Than 90 Seconds | Air/Fuel Ratio Lean Malfunction |
| 26 | Difference In Air/Fuel Ratio Of Oxygen Sensors | Air/Fuel Ratio Rich Malfunction |
| 27 (4) | Low Sensor Voltage Under Rich Condition | Sub-Oxygen Sensor |
| 28 | Fixed Oxygen Sensor Voltage | Main Oxygen Sensor (Right Bank ES300, Rear Side SC300) |
| 31 | Low Airflow Meter Voltage | For More Than .5 Second Airflow Meter |
| 32 | High Airflow Meter Voltage For More Than .5 Second | Airflow Meter (ES300 Only) |
| 35 | Open Or Short In Circuit For More Than .5 Second | High Altitude Compensator (HAC) Sensor |
| 41 | Open Or Short In Circuit For More Than .5 Second | Throttle Position Sensor |
| 42 | No Vehicle Speed Signal For 8 Seconds With 3000 RPM | Vehicle Speed Sensor |
| 43 (5) | No Starter Signal | Starter |
| 47 (6) | Open Or Short In Circuit For More Than .5 Second | Sub-Throttle Position Sensor |
| 51 | Idle Switch Off After 3 Seconds Running, Neutral Switch Off In "D, R, 2, 1" Or A/C Switch On | Switch Condition |
| 52 | No Knock Sensor Signal For 4 Crankshaft Revolutions At More Than 1600 RPM | Knock Sensor (Left Bank ES300, Front Side SC300) |
| 53 | No ECU Knock Signal | Knock Control |
| 55 | No Knock Sensor Signal For 4 Crankshaft Revolutions At More Than 1600 RPM | Knock Sensor (Right Bank ES300, Rear Side SC300) |
| 71 (4) | Low EGR Temperature | EGR System Malfunction |
| 78 | Open Or Short In Circuit At Less Than 1000 RPM | Fuel Pump Control (SC300) |
| (1) If diagnostic code displayed is not shown in this table, ECU is faulty. (2) All diagnostic codes except Codes 16, 43, 51 and 53 will remain in ECU memory until erased. (3) Electronically Controlled Transaxle (ECT). (4) ES300 California models and SC300 Federal models only. (5) Code 43 sets if vehicle is push-started (normal). (6) Code 47 for SC300 vehicles with traction control only. | ||
| (1) | If diagnostic code displayed is not shown in this table, ECU is faulty. |
| (2) | All diagnostic codes except Codes 16, 43, 51 and 53 will remain in ECU memory until erased. |
| (3) | Electronically Controlled Transaxle (ECT). |
| (4) | ES300 California models and SC300 Federal models only. |
| (5) | Code 43 sets if vehicle is push-started (normal). |
| (6) | Code 47 for SC300 vehicles with traction control only. |
CODE IDENTIFICATION (1)
CLEARING CODES
- Turn ignition off. Remove EFI fuse for at least 10 seconds. On LS400, EFI fuse (20A) is located in junction block No. 2. This junction block is located in left front engine compartment.
- On ES300, EFI fuse (15A) is located in fuse block, next to battery. On SC300 and SC400 models, EFI fuse (30A) is located in relay block at left strut tower. On all models, codes can also be cleared by disconnecting negative battery cable.
Note. If disconnecting negative battery cable to clear codes, reset clock and radio memory. After clearing codes, ensure a normal code is shown on CHECK ENGINE light.
ECU LOCATION
For ECU location (Scheme 10)or (Scheme 11).
Scheme 10
Scheme 11
Scheme 12
Scheme 13
Scheme 14
Scheme 15
Scheme 16
Scheme 17
Scheme 18
Scheme 19
CODE 21 & 28 - MAIN OXYGEN SENSOR CIRCUIT
Note. Code 21 is for left bank O2 sensor on ES300 or front side O2 sensor on SC300. Code 28 is for right bank O2 sensor on ES300 or rear side O2 sensor on SC300.
Scheme 20
Scheme 21
Scheme 22
CODE 25 & 26 - AIR FUEL RATIO MALFUNCTION
Note. Code 25 indicates air/fuel ratio is lean. Code 26 indicates air/fuel ratio is rich.
Scheme 23
Scheme 24
Scheme 25
Scheme 26
Scheme 27
Scheme 28
Scheme 29
Scheme 30
Scheme 31
Scheme 32
Scheme 33
Scheme 34
Scheme 35
Scheme 36
Scheme 37
Scheme 38
Scheme 39
CODE 52, 53 & 55 - KNOCK SENSOR SIGNAL
Note. Code 52 is for knock sensor signal of left bank on ES300 or front side on SC300. Code 53 is for ECU knock signal. Code 55 is for knock sensor signal of right bank on ES300 or rear side on SC300.
Scheme 40
Scheme 41
Scheme 42
Scheme 43
Scheme 44
SUMMARY
If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.
See also:
• CODE IDENTIFICATION
• 21
• 25
• 52