| Model | Year | Engine identification | System |
|---|---|---|---|
| Previa 2.4L | 1991-95 | 2TZ-FE | TCCS |
General information
- Engine control module (ECM) incorporates self-diagnosis function.
- Malfunction indicator lamp (MIL) will illuminate if certain faults are recorded.
- ECM operates in backup mode if sensors fail, to enable vehicle to be driven to workshop.
- ECM trouble codes can be accessed with suitable code reader connected to the data link connector (DLC) [1] or displayed by the MIL.
Accessing
- Switch ignition ON. Do NOT start engine.
- Check MIL illuminates.
- Switch ignition OFF.
- Jump DLC terminals TE1 and E1 0
- Switch ignition ON.
- Count MIL flashes and compare with trouble code table.
- First flashes of 0.5 second duration indicate ‘tens’, after a 1.5 second pause, next flashes of 0.5 second duration indicate ‘units'[2]
- A 2.5 second pause occurs between codes.
- After a 4.5 second pause, trouble codes will be repeated.
NOTE: The MIL flashes once every 0.25 seconds if the system is correct [3].
- Switch ignition OFF.
- Remove jump lead.
Preparatory conditions
- Battery voltage 11 V minimum.
- Closed throttle position (CTP) switch fully closed.
- Transmission in neutral position.
- All auxiliary equipment, including air conditioning, switched OFF.
- Engine at normal operating temperature.
Erasing
- Ensure ignition switched OFF.
- Remove EFI fuse (15A) from fascia fusebox 19.
- Wait 30 seconds.
- Reinstall fuse.
- Repeat checking procedure to ensure no data remains in ECM fault memory.
NOTE: Disconnecting battery ground lead will also erase trouble codes but may erase memory from electronic units such as radio.
Trouble code identification
Flash code | Fault location | Probable cause |
12 | Engine speed (RPM) sensor – circuit | Wiring, RPM sensor, ignition module, ECM |
13 | Engine speed (RPM) sensor- above 1000 rpm | Wiring, RPM sensor, ECM |
14 | Ignition reference signal – no signal | Wiring, ignition module, ECM |
21 | Heated oxygen sensor (H02S) -front -circuit | Wiring, H02S, ECM |
22 | Engine coolant temperature (ECT) sensor – circuit | Wiring, ECT sensor, ECM |
24 | Intake air temperature (IAT) sensor- circuit | Wiring, IAT sensor, ECM |
25 | Mixture control – continuously lean | Wiring, injector, H02S, ECTNAF sensor, intake/fuel/ignition system, ECM |
26 | Mixture control – continuously rich | Wiring, injector, fuel system, cold start injector, H02S, ECTNAF sensor, ECM |
27 | Heated oxygen sensor (H02S) – rear- circuit | Wiring, H02S, ECM |
31 | Volume air flow (VAF) sensor – circuit | Wiring, VAF sensor, ECM |
32 | Volume air flow (VAF) sensor- circuit | Wiring, VAF sensor, ECM |
41 | Throttle position (TP) sensor- circuit | Wiring, TP sensor, ECM |
42 | Vehicle speed sensor. (VSS) – circuit | Wiring, VSS, ECM |
43 | Starter signal – circuit | Wiring, ignition switch, engine control relay, ECM |
51 | Switch signal – closed throttle position (CTP) switch OFF during diagnosis | Wiring, CTP switch, ECM |
51 | Switch signal – park/neutral position (PNP) switch not in P or N during diagnosis | Wiring, PNP switch, ECM |
52 | Knock sensor (KS) – circuit | Wiring, KS, ECM |
53 | Knock control – malfunction | ECM |
71 | Exhaust gas recirculation (EGR) system – malfunction | Hose leak/blockage, wiring, EGRT sensor, EGR solenoid, ECM |