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Home >> Toyota >> 1994 >> Tercel Sedan 2-Door L4-1456cc 1.5L SOHC (3E) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Diagnostic Trouble Code Descriptions >> Engine Control System

Engine Control System



DIAGNOSTIC TROUBLE CODES

Including "normal", the ECM is programmed with the following 15 diagnostic trouble codes.

If 2 or more malfunctions are present at the same time, the lowest-numbered diagnostic trouble code will be displayed first.

All detected diagnostic trouble codes, except code No. 51, will be retained in memory by the ECM from the time of detection until canceled out.

Once the malfunction is corrected, the malfunction indicator lamp on the instrument panel will go off but the diagnostic trouble code(s) will remain stored in ECM memory (except for code No. 51).

If a malfunction is detected during the diagnostic trouble code check. refer to the circuit indicated in the table, and turn to the corresponding page.

Your readings may vary from the parameters listed in the table, depending on the instruments used.



CODE NUMBER -

System: Normal

Check Engine Light: OFF

Diagnosis: Normal output when no other code is recorded.

Trouble Area: -

CODE NUMBER 12 *2

System: RPM Signal

Check Engine Light: ON *1

Diagnosis: No NE signal is input to the ECU for 2 secs. or more after STA turns on.

Trouble Area: Open or short in distributor circuit, Distributor, Engine ECU

CODE NUMBER 13 *2

System: RPM Signal

Check Engine Light: ON *1

Diagnosis: No NE signal is input to the engine ECU for 2 secs. or more after STA turns ON.

Trouble Area: Open or short in distributor circuit, Distributor, Engine ECU

CODE NUMBER 14 *2

System: Ignition Signal

Check Engine Light: ON *1

Diagnosis: NE signal is not input to engine ECU for 0.3 sec. or more when engine speed is 1,500 rpm or more.

Trouble Area: Open or short IGF or IGT circuit from igniter to ECU, Igniter, Engine ECU

CODE NUMBER 21 *2

System: Oxygen Sensor Signal

Check Engine Light: ON *1

Diagnosis: At normal driving speed (below 60 mph and engine speed above 1,900 rpm), amplitude of oxygen sensor signal (OX) is reduced to between 0.35 - 0.70 V coninuously for 60 secs. or more. *6 (2 trip detection logic)

Trouble Area: Open or short in circuit of oxygen sensor, Oxygen sensor, Engine ECU

CODE NUMBER 22 *2

System: Water Temp. Sensor Signal

Check Engine Light: ON *1

Diagnosis: Open or short in water temp. sensor circuit for 0.5 sec. or more (THW)

Trouble Area: Open or short water temp. sensor circuit, Water temp. sensor, Engine ECU

CODE NUMBER 24 *2

System: Intake Air Temp. Sensor Signal

Check Engine Light: ON *1 *3

Diagnosis: Open or short in intake air temp. sensor circuit for 0.5 sec. or more (THA)

Trouble Area: Open or short intake air temp. sensor circuit, Intake air temp. sensor, Engine ECU

CODE NUMBER 25 *2

System: Air-Fuel Ratio Lean Malfunction

Check Engine Light: ON *1

Diagnosis: *4 (1) Oxygen sensor output is less than 0.45 V for at least 100 secs. when oxygen sensor is warmed up (racing at 2,000 rpm). (only for code 25), (2) When the engine speed varies by more than 40 rpm over the preceding crank angle period during a period of 50 secs. during idling with the coolant temp. 40°C (104°F) or more, *6 (2 trip detection logic (1) and (2)

Trouble Area: Engine ground bolt loose, Open in E1 circuit, Open in injector circuit, Fuel line pressure (injector blockage, etc.), Open or short in oxygen sensor circuit, Oxygen sensor, Ignition system, Water temp. sensor, Vacuum sensor, Engine ECU, EGR system

CODE NUMBER 26 *2 *5

System: Air-Fuel Ratio Rich Malfunction

Check Engine Light: ON *1

Diagnosis: *4 (1) Oxygen sensor output is less than 0.45 V for at least 100 secs. when oxygen sensor is warmed up (racing at 2,000 rpm). (only for code 25), (2) When the engine speed varies by more than 40 rpm over the preceding crank angle period during a period of 50 secs. during idling with the coolant temp. 40°C (104°F) or more, *6 (2 trip detection logic (1) and (2)

Trouble Area: Engine ground bolt loose, Short in injector circuit, Fuel line pressure (injector leakage, etc.), Open or short in oxygen sensor circuit, Oxygen sensor, Water temp. sensor, Vacuum sensor, Compression pressure, Engine ECU

CODE NUMBER 31 *2

System: Vacuum Sensor Signal

Check Engine Light: ON *1

Diagnosis: Open or short detected continuously for 0.5 sec. or more in vacuum sensor circuit (PIM)

Trouble Area: Open or short in vacuum sensor circuit, Vacuum sensor, Engine ECU

CODE NUMBER 41 *2

System: Throttle position Sensor Signal

Check Engine Light: ON *1 *3

Diagnosis: Open or short detected in throttle position sensor signal (VTA) for 0.5 sec. or more.

Trouble Area: Open or short in throttle position sensor circuit, Throttle position sensor, Engine ECU

CODE NUMBER 42 *2

System: Vehicle speed Sensor Signal

Check Engine Light: OFF

Diagnosis: SPD signal is not input to the engine ECU for at least 8 seconds during high load driving with engine speed between 2,500 rpm and 4,500 rpm (M/T), 2,500 rpm or more (A/T).

Trouble Area: Open or short in vehicle speed sensor circuit, Vehicle speed sensor, Engine ECU

CODE NUMBER 43 *2

System: Starter Signal

Check Engine Light: OFF

Diagnosis: Starter signal (STA) is not input to engine ECU even once until engine reaches 800 rpm or more when cranking.

Trouble Area: Open or short in starter signal circuit, Open or short in IG SW circuit, Engine ECU

CODE NUMBER 71 *2 *5

System: EGR System Malfunction

Check Engine Light: ON *1

Diagnosis: With the coolant temp. at 70°C (158°F) or more, 50 secs. from start of EGR operation, the EGR gas temp. is less than 70°C (158°F) and the EGR gas temp. has risen less than 10°C (18°F) * (2 trip detection logic)

Trouble Area: Open in EGR temp. sensor circuit, Open in VSV circuit for EGR, EGR vacuum hose disconnected, valve stuck, Clogged in EGR gas passage, Engine ECU

CODE NUMBER 51 *7

System: Switch Condition Signal

Check Engine Light: OFF

Diagnosis: Displayed when A/C in ON, IDL contact OFF or shift position in "R", "D", "2", or "1" ranges with the check terminals E1 and T connected.

Trouble Area: A/C switch circuit, Throttle position sensor IDL circuit, Neutral start switch circuit, Accelerator pedal, cable, Engine ECU

FOOTNOTES

*1: "ON" indicates that the Malfunction Indicator Lamp (MIL) is lighted up when a malfunction is detected. "OFF" indicates that the MIL does not light up during malfunction diagnosis, even if a malfunction is detected.

*2: Indicates that a diagnostic trouble code is recorded in the ECM memory when a malfunction occurs.

*3: The MIL comes on if a malfunction occurs only for California specifications.

*4: No.(2) in the diagnostic contents of codes No.25 and 26 apply to California specification vehicles only, while (1) applies to all models.

*5: Code 26 and 71 is used only for California specifications.

*6: 2 trip detection logic.

*7: Indicates that a diagnostic trouble code is not recorded in the ECM memory even if a malfunction occurs. Accordingly, output of diagnostic results is performed with the ignition switch ON.
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