Fisher Posted June 10, 2013 Share Posted June 10, 2013 After my Engine Management light came on I did hours of browsing and research and found thisI thought it may be of use for some 1 else as I couldn't find this on UKSO siteHope it helps ECU Diagnostic Codes for many Toyota ECUsSome codes may not exist in earlier or non-applicable engine ECU’s but all codes are common among many Toyota ECUs.It is essential that you do have the proper manuals and skills necessary to perform diagnostic and repairs.This list is to assist those who are qualified in obtaining some information out of the ECU on cars equipped with factory units.Diagnosis System: To obtain ECU codes, proceed as follows:Initial conditions must be met for codes to appear in normal output.• Battery Voltage must be 11V or more• Throttle valves must be fully closed (on newer engines)• Accessories switched off• Engine at operating temperature1. Turn the ignition switch ON. (Do not start engine)2. Short terminals TE1 and E1 of the check connector of the diagnosis connector cluster.Diagnostic Codes:Normal Operation: (no malfunction)The light will alternatively blink ON and OFF at 0.26 second intervals. Malfunction Codes IndicationIn the event of a registered malfunction, the light will blink every 0.52 second. The first series of blinks will equal the 1st digit of a 2 digit code and after a 1.5 second pause; the second series of blinks will indicate the 2nd digit.If there are 2 or more codes, there will be a 2.5 seconds pause between each signalled code. After all codes have flashed, there will be a 4.5 second interval and the codes will repeat until TE1 and E1 has been disconnected.2-Trip detection logic:Diagnostic Codes 20-29 are usually indicated with 2 -trip logic. This means that the ECU will need two repeated engine operational cycles, with the same problem for the code to be indicated, minimizing the false codes. The ignition must be switched OFF between the 2 successive engine operations.Test Mode: (1989 and later ECU, with variation in models)In this mode, the ECU will have increased sensing ability for malfunction detection. It can also detect starter signal circuit, and air conditioning components. The same codes also will be detected as those of the normal modes.In the same manner and conditions as the normal diagnostic:1. Short the TE2 and E1 of the diagnostic connector.2. Turn ignition ON to begin diagnosis in TEST mode.3. To check that the TEST mode is operational, confirm that the warning light flashes with ignition in ON position.4. Start the engine and drive the vehicle at or faster than 10km/h (6mph). If the speed fails to reach this the ECU will falsely report that the starter and speed sensor is malfunctioning. (Code 41 and 42)5. After test drive, short connectors TE1 and E16. Read diagnostic codes.Be sure to Remove SST from check connector when finished.*Warning:* Test mode will not start if terminals are shorted after ignition is turned ON. Code 51 (AC compressor switch signal) is erratic by nature and will sometimes come on without malfunction.Code | Signal Diagnosis and Common Trouble Area1 System OK2 MAP Sensor or Circuit3 Ignition Signal from Amplifier4 CTS/Circuit6 RPM Signal or Circuit7 Throttle Position Sensor (TPS) or Circuit8 ATS/Circuit9 Vehicle Speed Sensor/Circuit10 Cranking Signal or Circuit11 A/C Switch or Circuit12 RPM SignalNo G or NE signal present for 2 seconds during cranking Open G circuitOpen, short in G or NE circuit. Distributor ECU13 RPM signalNo NE signal for 50msec at 1000rpm. Open G circuitOpen, short in G or NE circuit. Distributor ECU14 Ignition No IGF signal to ECU for 4 consecutive IGT signal during engine running Open/short in IGF/IGT signal from Igniter to ECU Igniter malfunction ECU15 Starter Signal Circuit Coil pack wires16 ECT Control Signal or Circuit21 O2 sensor Open/short in heater circuit of Oxygen (O2) sensor for 0.5 secondsAmplitude of O2 sensor reduced to 0.35-0.70V continuously for more than 60 seconds O2 sensorVacuum sensorECU22 Water Temperature Sensor no signal at THW Water temperature sensorECU24 Intake Air Temp sensor no signal at THA Intake air temp sensorECU25 Air/Fuel mixture Lean Oxygen (O2) sensor output in less than 0.45 volts for at least 90 seconds when O2 sensor is warmed and 1500 rpm or above. Open injector circuitLack of fuel pressureIgnition systemVacuum sensorO2 sensorECU26 Oxygen (O2) Sensor Rich Signal or Circuit27 Oxygen (O2) Sensor/Circuit28 Oxygen (O2) Sensor/Circuit31 Vacuum SensorNo signal at Vacuum sensor (PIM)Vacuum sensor to ECU32 Vane Airflow Sensor or Circuit33 ISCV (Idle speed control valve)Open or short in ISCV circuitISCV Valve34 Turbo Pressure Signal or Circuit35 Turbo Pressure Signal or Circuit41 Throttle Position Sensor (TPS)No signal for 0.5 seconds or more at ignition ON. (VTA) ECU42 Vehicle Speed Sensor (VSS)No speed sensor signal to ECU when loaded driving condition with engine speeds 2000 to 5000 rpm.For 8 seconds or more. ECU43 Starter No starter signal to ECU when cranking in TEST mode.Terminal STA on ECUStarter signal circuitStarter relayIgnition switch47 Throttle Position Sensor (TPS) or Circuit51 Switch Condition Signal displayed when A/C is on when TE1 and E1 connected in test mode A/C switchAccelerator pedal, cableECU52 #1 Knock SensorNo KNK1 signal to ECUKnock sensor looseMalfunctioning knock sensor53 #2 Knock SensorNo KNK2 signal to ECU Knock sensor loose Malfunctioning Knock Sensor54 Turbo Intercooler Signal or Circuit55 Knock Sensor or Circuit Quote Link to post Share on other sites
morgey Posted June 10, 2013 Share Posted June 10, 2013 This should really be stickied tbf. Very handy and worthwhile information Quote Link to post Share on other sites
Fisher Posted June 11, 2013 Author Share Posted June 11, 2013 how do we get the mods to make it sticky like I say I was looking around for hours to find something that was user friendly as most I found was very confusing this did the job in minutes Quote Link to post Share on other sites
morgey Posted June 11, 2013 Share Posted June 11, 2013 Duno normally if they see it they sticky it, could try pm'ing them with a link to it maybe? Quote Link to post Share on other sites
Fisher Posted June 12, 2013 Author Share Posted June 12, 2013 thanks Quote Link to post Share on other sites
ryan lang Posted June 13, 2013 Share Posted June 13, 2013 needs stickyingstickying done Quote Link to post Share on other sites
SmurfyBhoy Posted July 25, 2013 Share Posted July 25, 2013 42 appears now and then ??? Quote Link to post Share on other sites
shaeeb Posted June 20, 2015 Share Posted June 20, 2015 Hi guys, check engine light came on throwing codes 12 and 42 > rpm and speed faults> problem is the car runs fine tachometer and speedo work ok, reset the ecu by unplugging 15a fuse, codes clear but reappear after a day, I'm running a blitz access ecu, I hope the ecu isn't playing up, is there any other checks I could do or replace igniter or dizzy before condemning the ecu?Thanks Quote Link to post Share on other sites
Prime-Beardimus Posted April 29, 2018 Share Posted April 29, 2018 Mine flashed up 22/24/99 i cant seem to find a 99 code anywhere Quote Link to post Share on other sites
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