INTRODUCTION
If no faults were found while performing BASIC TESTING , proceed with self-diagnostics. If no fault codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).
HARD FAILURES
Hard failures cause malfunction light to illuminate 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, Electronic Control Unit (ECU) will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK engine light to flicker or illuminate and go out after the intermittent fault goes away. However, the corresponding trouble code will be retained in ECU memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECU memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.
NORMAL MODE
- 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, transmission is in Neutral and all accessories are off.
- The Total Diagnostic Communication Link (TDCL) connector is located under left side of instrument panel. (Scheme 6) Diagnostic codes can be obtained through TDCL connector or check connector. Check connector is located in engine compartment near left shock tower. (Scheme 7)
- 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 8) Count number of flashes from CHECK engine light.
- If CHECK engine light flashes 2 times every second, this indicates system is normal. If a diagnostic code is displayed, first group of flashes will provide first digit of a 2-digit diagnostic code. There will be a 1.5 second delay between first digit and second digit of diagnostic code. The second group of flashes will equal second digit of diagnostic code.
- If more than one code is stored, there will be a 2.5 second delay between diagnostic codes. After all diagnostic codes have been displayed, a 4.5 second delay will occur, then diagnostic 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 «DIAGNOSTIC CODE IDENTIFICATION»(/lexus/es/v20-1989-1991/remont/testing-diagnostics/#engine-controls-tests-wcodes) table for description of possible circuit problem. After reading diagnostic code description, see appropriate diagnostic code chart. To clear codes, see CLEARING CODES in this article.
Scheme 6
Scheme 7
Note. Test Mode is not available on ES250.
Scheme 8
| Code (2) | CHECK Engine Light | Signal Affected |
|---|---|---|
| 12 | On | RPM |
| 13 | On | RPM |
| 14 | On | Ignition |
| 16 | On | (3) ECT Control |
| 21 | On | Main Oxygen Sensor Or Sensor Heater |
| 22 | On | Water Temperature Sensor |
| 24 | On (Calif. Only) | Intake Air Temperature Sensor |
| 25 | On | Air/Fuel Ratio Lean Malfunction |
| 26 | On | Air/Fuel Ratio Rich Malfunction |
| 27 | On | Sub-Oxygen Sensor (California Only) |
| 31 | On | Airflow Meter |
| 32 | On | Airflow Meter |
| 41 (4) | On (Calif. Only) | Throttle Position Sensor |
| 42 | Off | Vehicle Speed Sensor |
| 43 (5) | Off | Starter |
| 51 | Off | Switch Condition |
| 52 | On | Knock Sensor |
| 53 | On | Knock Control |
| 71 (4) | On | EGR System Malfunction (California Only) |
| (1) If diagnostic code displayed is not shown in this table, ECU is faulty. (2) All diagnostic codes except Codes 16, 51 and 53 will remain in ECU memory until erased. (3) Electronically Controlled Transmission (ECT). (4) California vehicles only. (5) Code 43 sets if vehicle is push started. | ||
| (1) | If diagnostic code displayed is not shown in this table, ECU is faulty. |
| (2) | All diagnostic codes except Codes 16, 51 and 53 will remain in ECU memory until erased. |
| (3) | Electronically Controlled Transmission (ECT). |
| (4) | California vehicles only. |
| (5) | Code 43 sets if vehicle is push started. |
DIAGNOSTIC CODE IDENTIFICATION (1)
TRANSMISSION DIAGNOSIS
If the vehicle is equipped with a computer controlled automatic transmission, the transmission computer diagnostic codes may be retrieved using the O/D OFF indicator light.
O/D OFF INDICATOR LIGHT
Note. When retrieving transmission trouble codes, ensure overdrive switch is in the ON position.
- Turn ignition switch to the ON position, but do not start engine. Turn O/D switch on. Using a jumper wire, connect terminals TE1 and E1 at TDCL or check connector. (Scheme 8) Read the trouble codes as indicated by the number of flashes of O/D OFF light.
- If no transmission trouble codes are present, the light will blink continuously 2 times per second. Trouble code flashes will be at the rate of one flash per second with longer pauses separating digits and codes. Refer to ES250 AUTOMATIC TRANSMISSION CODE IDENTIFICATION table. Refer to appropriate transmission diagnostic chart. For location of transmission components (Scheme 9)
- If a malfunction is encountered with transmission and no diagnostic codes are set, refer to transmission diagnostic charts located at rear of ES250 diagnostic charts. These charts will diagnose the following malfunctions: No shifting Shift point too high or too low No upshift to overdrive (after warm-up) No lock-up (after warm-up)
To clear codes, see CLEARING CODES in this article.
Note. If both speed sensors No. 1 and No. 2 fail simultaneously, no diagnostic code will be set and fail-safe system will not function. After this occurs, when driving in D range, transmission will not upshift from first gear, regardless of vehicle speed.
| Code (1) | Signal Affected |
|---|---|
| N/A | (2) Normal |
| 42 | Speed Sensor No. 1 Signal |
| 61 | Speed Sensor No. 2 Signal |
| 62 | Solenoid Valve No. 1 Signal |
| 63 | Solenoid Valve No. 2 Signal |
| 64 | Lock-Up Solenoid Signal |
| (1) If Codes 62, 63, or 64 are displayed, an electrical malfunction is present in the solenoid. Stuck valves will not appear. (2) O/D OFF light will blink 2 times every second. | |
| (1) | If Codes 62, 63, or 64 are displayed, an electrical malfunction is present in the solenoid. Stuck valves will not appear. |
| (2) | O/D OFF light will blink 2 times every second. |
ES250 AUTOMATIC TRANSMISSION CODE IDENTIFICATION
Scheme 9
CLEARING CODES
Turn ignition off. Remove EFI fuse (20A) for at least 10 seconds. EFI fuse is located in fuse block, next to battery. Codes can also be cleared by disconnecting negative battery cable.
Note. When disconnecting negative battery cable to clear codes, remember to reset clock and radio memory. After clearing codes, ensure a normal code is shown on CHECK engine light.
ECU LOCATION
SUMMARY
If no hard fault codes are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnosis procedures.
DIAGNOSTIC CHARTS
Note. The following charts are courtesy of Toyota Motor Sales, U.S.A., Inc.
