1993 Toyota Corolla Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Trouble Code Identification

TROUBLE CODE IDENTIFICATION (1)(2)

CODE No. System Affected NORMAL MODE TEST MODE Probable Cause
12  RPM Signal ON N/A Distributor, Starter or Ckt, ECM
13  RPM Signal (3) (4) Distributor or Ckt, ECM
14  Ignition Signal ON N/A Ignitor or Ckt to ECM. ECM
16 (1.8L)  Elect. Controlled A/T Signal ON N/A ECM or Ckt
21  O2 Sensor Signal ON ON O2 Sensor or Ckt, ECM
22  Coolant Temp. Sensor Signal ON ON Coolant Temp. Sensor or Ckt, ECM
24  Intake Air Temp. Sensor Signal ON (5) ON Intake Air Temp. Sensor or Ckt, ECM
25  Lean Air/Fuel Mixture ON ON Loose Ground, Injector or Ckt, Fuel Pressure, Ignition System, Coolant Temp. Sensor,Airflow Meter, Vacuum Sensor,O2 Sensor or Ckt, CompressionPressure, ECM
26 (6) Rich Air/Fuel Mixture ON ON Loose Ground, Injector or Ckt, Fuel Pressure, Ignition System, Coolant Temp. Sensor,Airflow Meter, Vacuum Sensor,O2 Sensor or Ckt, Cold Start Injector or Ckt, Compression Pressure, ECM
27 (6) Sub-O2 Sensor Signal ON ON Sub-O2 Sensor or Ckt, ECM
31  MAP Sensor ON ON MAP Sensor or Ckt, ECM
41  TPS Signal ON (5) ON Throttle Position Sensor or Ckt, ECM
42  Vehicle Speed Sensor Signal ON OFF Vehicle Speed Sensor or Ckt, ECM
43  Starter Signal N/A OFF Starter Signal Ckt, Main Relay, Ignition Switch or Ckt, ECM
51  Switch Condition Signal N/A OFF A/C Switch, Park/Neutral Switch or Ckt, TPS or Ckt, ECM
52 (1.8L)  Knock Sensor Signal ON N/A Knock Sensor or Ckt, ECM
71 (6) EGR System Malfunction ON ON EGR System, EGR Temp. Sensor or Ckt, EGR-VSV, ECM
(1) The 1.6L is the 4A-FE engine and 1.8L is the 7A-FE engine.
(2) ON indicates MIL on instrument panel will be illuminated. N/A indicates item is not included in malfunction diagnosis when using this mode. OFF indicates MIL on instrument panel will be not be illuminated even if malfunction is detected.
(3) The MIL will only be illuminated if no "NE" signal to ECM is received at 1500 RPM or more. If no "G" signal to ECM is received while "NE" signal is input 4 times to ECM when engine speed is 500-4000 RPM, MIL will not be illuminated.
(4) The MIL will not be illuminated if no "NE" signal to ECM is received at 1500 RPM or more. If no "G" signal to ECM is received while "NE" signal is input 4 times to ECM when engine speed is 500-4000 RPM, the MIL will be illuminated.
(5) The MIL will be illuminated on Calif. models only.
(6) Applies to California models only.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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