Toyota Code Retrieval
Accessing Diagnostic Trouble Codes
1982-87
The ECU self diagnosis circuit detects and stores system malfunctions
related to the various sensor and actuator circuits. These malfunctions are
stored as DTC's in the ECU memory as long as battery voltage is applied to
the ECU, and in most cases, the Check Engine lamp will flash as long as a
malfunction is present. By analyzing these DTC's, system malfunctions can be
easily diagnosed and repaired. To obtain DTC's stored in the ECU memory,
proceed as follows:
- Turn ignition switch to On position and observe "Check
Engine" lamp, then start engine and observe lamp.
- If lamp fails to light with ignition switch on (engine stopped), or if
lamp fails to go out or flash a diagnostic trouble code after engine
starts, check diagnosis circuit.
- Run engine until it reaches normal operating temperature, then stop
engine.
- Ensure that battery voltage is at least 11 volts, throttle valve is
fully closed, A/C is off and that transmission selector is in park or
neutral. Turn ignition switch on but do not start engine.
1984 5M.GE Engine
- Short terminals of check engine connector, using a jumper wire, and
connect a suitable analog voltmeter to EFI connector, using harness
09842-14010. Use a analog voltmeter with a high (10K ohm) impedance.
- Diagnostic trouble codes will be indicated by voltmeter deflection in
the 0-25 volt and 2.5-5.0 volt ranges.
Except Cressida & Supra
Equipped w/Super Monitor Display
- Short terminals of check engine connector or service connector
(depending on model) with suitable jumper wire.
- Diagnostic trouble codes will be indicated by the number of flashes of
the "Check Engine" lamp.
Cressida & Supra Equipped
w/Super Monitor Display
- With ignition On and engine not running, simultaneously depress and
hold Select and Input M keys of Super Monitor display for at least three
seconds.
- The letters DIAG will appear on the display. After a short pause,
depress and hold Set key for at least three seconds. If there are no
DTC's stored in the ECU, the display will read E/G OK or ENG-OK
(depending on models). If there are DTC's stored in the ECU, the DTC
number will appear on the display. If there is more than one DTC, there
will be a three second pause between DTC's.
- After accessing diagnostic trouble codes, clear display by turning Off
ignition switch or depress the Super Monitor Display key so the time
appears.
1988-95 Normal Mode
Prior to considering the TCCS system as cause for a complaint, ensure the
battery is fully charged and the engine and all related systems are
operating properly. When diagnosing TCCS malfunctions, observe all
precautions and follow procedures as outlined to ensure successful repairs.
The ECM (ECU) self diagnosis circuit detects and stores system
malfunctions related to the various sensor and actuator circuits. These
malfunctions are stored as DTC's in the ECM (ECU) memory as long as battery
voltage is applied to the ECM (ECU), and in most cases, the Check Engine
lamp will flash as long as a malfunction is present. By analyzing these
DTC's, system malfunctions can be easily diagnosed and repaired. To obtain
DTC's stored in the ECM (ECU) memory, proceed as follows:
- Short terminals of check engine connector or service connector
(depending on model) with suitable jumper wire.
- Diagnostic trouble codes will be indicated by the number of flashes of
the Check Engine lamp.
Two Trip Detection Logic
When a logic malfunction is first detected, the malfunction is
temporarily stored in the ECM (ECU) memory. If the same case is detected
again during the second drive test, the second detection causes the Check
Engine light to illuminate. In order for this mode to store DTC's, the
ignition switch must be turned Off between the first and the second test.
Refer to "Diagnostic Trouble Code Interpretation" in each specific
section for applicable two trip detection logic DTC's.
Test Mode
The test mode has a higher sensing ability to detect faults than in
normal mode. It can detect malfunctions in the starter signal circuit, air
conditioning signal and neutral start switch signal. In addition, the test
mode also detects the same malfunctions as in the normal mode.
- Ensure battery voltage is at least 11 volts, throttle valve is fully
closed, transmission is in neutral position and accessories in Off
position.
- Short check service connector terminals TE2 and El, with suitable
jumper wire, then turn ignition switch On to enter test mode, check
engine lamp should illuminate. Test mode may not be entered if terminals
TE2 and El are shorted after ignition switch is turned On.
- Start engine and drive vehicle at 10 mph or higher. If vehicle is not
driven vehicle speed signal DTC's 42 and 43 may be stored.
- Simulate malfunction conditions.
- Using suitable jumper wire, short check connector terminals TE1 and
El, then read DTC's.
Toyota Hand-Held Tester
Diagnostic trouble codes may be retrieved by connecting the Toyota
hand-held tester to the diagnostic link connector (DLC), then following the
prompts on the tester screen.
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