SFI SYSTEM (w/o Electronic Throttle Control System) TERMINALS OF ECM

A0135W2E01

Tech Tips

Each ECM terminal's standard normal voltage is shown in the table below.

In the table, first follow the information under "Condition". Look under "Symbols (Terminals No.)" for the terminals to be inspected. The standard normal voltage between the terminals is shown under "STD Voltage". Use the illustration above as a reference for the ECM terminals.

Symbols (Terminals No.) Wiring Color Terminal Description Condition STD Voltage
BATT (B25-42) - E1 (B26-24) LG - W-B Battery (for measuring battery voltage and for ECM memory) Always 9 to 14 V
IGSW (B25-47) - E1 (B26-24) R - W-B Ignition switch Ignition switch ON 9 to 14 V
+B (B26-3) - E1 (B26-24) P - W-B Power source of ECM Ignition switch ON 9 to 14 V
MREL (B25-66) - E1 (B26-24) GR - W-B EFI relay Ignition switch ON 9 to 14 V
VC (B25-29) - ETA (B25-40) Y - BR Power source of throttle position sensor (specific voltage) Ignition switch ON 4.5 to 5.5 V
VC2 (B25-9) - E21 (B25-20) R - BR Power source of manifold absolute pressure sensor (specific voltage) Ignition switch ON 4.5 to 5.5 V
VCG1 (B25-30) - E1 (B26-24) O - W-B Power source of camshaft position sensor (specific voltage) Ignition switch ON 4.5 to 5.5 V
PIM (B25-81) - E21 (B25-20) Y - BR Manifold absolute pressure sensor Idling 1.2 to 2.0 V
VTA (B25-80) - ETA (B25-40) GR - BR Throttle position sensor (for engine control) Ignition switch ON, Accelerator pedal fully released 0.4 to 0.9 V
VTA (B25-80) - ETA (B25-40) GR - BR Throttle position sensor (for engine control) Ignition switch ON, Accelerator pedal fully depressed 3.6 to 4.3 V
THA (B25-19) - E21 (B25-20) w -BR Intake air temperature sensor Idling, Intake air temperature 20°C (68°F) 1.5 to 3.0 V
THW (B26-9) - E2 (B26-32) R - BR Engine coolant temperature sensor Idling, Engine coolant temperature 80°C (176°F) 0.2 to 1.0 V

#1 (B26-25) - E01 (B25-1)

#2 (B26-34) - E01 (B25-1)

#3 (B26-26) - E01 (B25-1)

W - W-B

B - W-B

R - W-B

 Injector Ignition switch ON 9 to 14 V

IGT1 (B25-68) - E1 (B26-24)

IGT2 (B25-50) - E1 (B26-24)

IGT3 (B25-49) - E1 (B26-24)

G - W-B

B - W-B

O - W-B

 Ignition coil with igniter (ignition signal) Idling Pulse generation (See waveform 1)
G1 (B25-55) - G- (B25-56) R - W-B Camshaft position sensor Idling Pulse generation (See waveform 2)
NE+ (B25-27) - NE- (B25-8) P - L Crankshaft position sensor Idling Pulse generation (See waveform 2)

ISC (B25-3) - E1 (B26-24)

ISC2 (B25-4) - E1 (B26-24)

ISC3 (B25-23) - E1 (B26-24)

ISC4 (B25-22) - E1 (B26-24)

G - W-B

L - W-B

LG - W-B

R - W-B

 Idle control valve Idling Pulse generation (See waveform 3)
STA (B25-73) - E1 (B26-24) GR - W-B Starter signal Cranking 5.5 V or more
FC (B26-28) - E1 (B26-24) G - W-B Fuel pump control Ignition switch ON 9 to 14 V
OX1A (B26-18) - E11 (B26-19) W - B Heated oxygen sensor (Sensor 1) Maintain engine speed at 2,500 rpm for 2 minutes after warming up sensor Pulse generation (See waveform 4)
OX1B (B26-17) - E12 (B26-11) Y - BR Heated oxygen sensor (Sensor 2) Maintain engine speed at 2,500 rpm for 2 minutes after warming up sensor Pulse generation (See waveform 5)
HT1A (B26-21) - E1 (B26-24) L - W-B Heated oxygen sensor heater Ignition switch ON 9 to 14 V
HT1B (B26-23) - E1 (B26-24) R - W-B Heated oxygen sensor heater Ignition switch ON 9 to 14 V
KNK1 (B25-71) - KNK2 (B25-52) G - R Knock sensor Maintain engine speed at 4,000 rpm after warming up engine Pulse generation (See waveform 6)
OCV- (B26-1) - E1 (B26-24) G - W-B Camshaft timing oil control valve Idling Pulse generation (See waveform 7)
EVP1 (B26-27) - E1 (B26-24) V - W-B EVAP VSV Ignition switch ON 9 to 14 V
W (B25-24) - E1 (B26-24) O - W-B MIL Ignition switch ON (MIL goes on) Below 3.0 V
SPD (B25-54) - E1 (B26-24) Y - W-B Speed signal from skid control ECU Ignition switch ON, Rotate driving wheel slowly Pulse generation

  1. WAVEFORM 1

    A01393WE02
    Igniter IGT signal (from ECM to igniter)
    ECM Terminal Name Between IGT1 (to IGT3) and E1
    Tester Range 2 v/DIV, 100 ms/DIV
    Condition Idling

    Tech Tips

    The wavelength becomes shorter as engine rpm increases.

  2. WAVEFORM 2

    A01375DE10
    Camshaft position sensor, Crankshaft position sensor
    ECM Terminal Name

    (a) Between G1 and G-

    (b) Between NE+ and NE-
    Tester Range 5 v/DIV, 20 ms/DIV
    Condition Idle after engine warmed-up

    Tech Tips


    • The wavelength becomes shorter as engine rpm increases.

  3. WAVEFORM 3

    A0138LKE04
    ISC valve signal
    ECM Terminal Name

    (a) Between ISC and E1

    (b) Between ISC2 and E1

    (c) Between ISC3 and E1

    (d) Between ISC4 and E1
    Tester Range 5 v/DIV, 10 ms/DIV
    Condition Idle with warm engine

    • The waveform varies depending on idle speed control valve.

    • When the idling speed is constant, the waveform may remain high or low. Under this condition, check the waveform by racing the engine.

  4. WAVEFORM 4

    A0138XEE24
    HO2S (sensor 1)
    ECM Terminal Name Between OX1A and E11
    Tester Range 0.2 v/DIV, 200 ms/DIV
    Condition Maintain engine RPM at 2,500 rpm after engine warmed-up

    Tech Tips

    In the DATA LIST, the items HO2S B1 S1 show the ECM input values of the HO2S (sensor 1).

  5. WAVEFORM 5

    A0136TTE28
    HO2S (sensor 2)
    ECM Terminal Name Between OX1B and E12
    Tester Range 0.2 v/DIV, 200 ms/DIV
    Condition Maintain engine RPM at 2,500 rpm after engine warmed-up

    Tech Tips

    In the DATA LIST, the items HO2S B1 S2 show the ECM input values of the HO2S (sensor 2).

  6. WAVEFORM 6

    A0136GHE19
    Knock sensor
    ECM Terminal Name Between KNK1 and KNK2
    Tester Range 1 v/DIV, 1 ms/DIV
    Condition Maintain engine RPM at 4,000 rpm after engine warmed-up

    Tech Tips


    • The wavelength becomes shorter as engine rpm increases.

    • The waveforms and amplitudes displayed differ slightly depending on the vehicle.

  7. WAVEFORM 7

    A0136MYE08
    VVT OCV
    ECM Terminal Name Between OCV- and E1
    Tester Range 5 v/DIV, 1 ms/DIV
    Condition Idling

    Tech Tips

    In the DATA LIST, the items VVT OCV DUTY shows the duty ratio of voltage applied to the OCV (see the illustration above).

    VVT OCV DUTY = A/B x 100 (%)