CHECK AT THE ECU TERMINALS



 1.Connect a needle-nosed wire probe to a voltmeter probe.
2.Insert the needle-nosed wire probe into each of the engine-ECU connector terminals from the wire side, and measure the voltage while referring to the check chart.
note
  1. Make the voltage measurement with the engine-ECU connector connected.
  2. You may find it convenient to pull out the engine-ECU to make it easier to reach the connector terminals.
  3. The checks can be carried out off the order given in the chart.
caution Short-circuiting the positive (+) probe between a connector terminal and earth could damage the vehicle wiring, the sensor, engine-ECU or all of them. Be careful to prevent this!
3.If voltmeter shows any division from standard value, check the corresponding sensor, actuator and related electrical wiring, then repair or replace.
4.After repair or replacement, recheck with the voltmeter to confirm that the repair has corrected the problem.

TERMINAL VOLTAGE CHECK CHART




Terminal No.
 Terminal code
 Inspection Item
 Check condition (Engine condition)
 Normal condition
1
 ETV+
 Throttle valve control servo (+)
  • Ignition switch: ON
  • Accelerator pedal: fully opened → fully closed

Decreases slightly (approximately 2 V) from the battery voltage
2
 ETV-
 Throttle valve control servo(-)
  • Ignition switch: ON
  • Accelerator pedal: fully closed → fully opened

 Decreases slightly (approximately 2 V) from the battery voltage
3
 OHFL
 Oxygen sensor (front) heater
 Engine: Idle operation after warm-up
(20 seconds after starting engine)
 2.5 - 4.5 V*1
Engine: Racing
 System voltage
4
 OHRL
 Oxygen sensor (rear) heater
 Engine: Idle operation after warm-up
(20 seconds after starting engine)
 2.5 - 4.5 V*1
Engine: Racing
 System voltage
5
 SGT
 Crank angle sensor
 Engine: Cranking
 0.4 - 4.0 V*1
Engine: Idle operation
 2.0 - 3.0 V*1
6
 SGC
 Camshaft position sensor
 Engine: Cranking
 2.0 - 4.8 V*1
Engine: Idle operation
 3.0 - 4.0 V*1
7
 ALTG
 Alternator G terminal
  • Engine: Idle operation after warm-up
  • Radiator fan: Non-operation
  • Head lamp switch: OFF → ON
  • Stop lamp: OFF → ON
  • Rear defogger switch: OFF → ON

 Voltage rises
8
 CIL1
 Ignition coil No. 1
 Engine: 3,000 r/min


 0.3 - 3.0 V*1
23
 CIL2
 Ignition coil No. 2
35
 CIL3
 Ignition coil No. 3
34
 CIL4
 Ignition coil No. 4
9
 INJ1
 No. 1 injector
 Engine: While engine is idling after having warmed up, suddenly depress the accelerator pedal


 From 9 - 15 V*1, it is slightly reduced temporarily.
10
 INJ2
 No. 2 injector
24
 INJ3
 No. 3 injector
25
 INJ4
 No. 4 injector
11
 PURG
 Purge control solenoid valve
 Ignition switch: ON
 System voltage
Engine: 3,000 r/min after warm-up (with 3 minutes after the engine starting sequence is completed)
 Voltage decreases
12
 OFLE
 Oxygen sensor (front) offset voltage
 Ignition switch: ON
 0.4 - 0.6 V
13
 O2FL
 Oxygen sensor (front)
 Engine: Maintain 2,500 r/min after warm-up
 0.9 V or less <=> 1.1 - 1.5 V (changes repeatedly)
14
 MAP
 Manifold absolute pressure sensor
 Ignition switch: ON
 At 0 m altitude
 3.8 - 4.2 V
At 600 m altitude
 3.5 - 3.9 V
At 1,200 m altitude
 3.3 - 3.7 V
At 1,800 m altitude
 3.0 - 3.4 V
Engine: Idle operation after warm-up
 0.6 - 1.4 V
Engine: While the engine is idling after warm-up, quickly depress the accelerator pedal
 Varies depending on the negative pressure at the inlet manifold
15
 5V
 Sensor impressed voltage
 Ignition switch: ON
 4.9 - 5.1 V
19
 TPS5
 Applied voltage to the throttle position sensor
 Ignition switch: ON
 4.9 - 5.1 V
21
 ALTF
 Alternator FR terminal
  • Engine: Idle operation after warm-up
  • Head lamp switch: OFF → ON
  • Stop lamp: OFF → ON
  • Rear defogger switch: OFF → ON

 Voltage decreases
22
 ALTL
 Alternator L terminal
 Ignition switch: ON
 0.5 - 2.0 V
Engine: Idle operation
 System voltage
26
 ORLE
 Oxygen sensor (rear) offset voltage
 Ignition switch: ON
 0.4 - 0.6 V
27
 O2RL
 Oxygen sensor (rear)
  • Transmission: 2nd
  • The engine speed is maintained to 3,500 r/min or more during an accelerated driving with the throttle full-open

 1.0 - 1.5 V
28
 WTS
 Engine coolant temperature sensor
 Ignition switch: ON
 When engine coolant temperature is -20°C
 3.9 - 4.5 V
When engine coolant temperature is 0°C
 3.2 - 3.8 V
When engine coolant temperature is 20°C
 2.3 - 2.9 V
When engine coolant temperature is 40°C
 1.3 - 1.9 V
When engine coolant temperature is 60°C
 0.7 - 1.3 V
When engine coolant temperature is 80°C
 0.3 - 0.9 V
29
 ATS
 Intake air temperature sensor
 Ignition switch: "ON"
 When the intake air temperature is -20°C
 3.8 - 4.4 V
When the intake air temperature is 0°C
 3.2 - 3.8 V
When the intake air temperature is 20°C
 2.3 - 2.9 V
When the intake air temperature is 80°C
 0.4 - 1.0 V
30
 TPSM
 Throttle position sensor (main)
  • Remove the intake air hose at the throttle body.
  • Disconnect the connector of the electronic-controlled throttle valve.
  • With the special tool test harness (MB991658) bridge only the mating terminals of No. 3, No. 4, No. 5, and No. 6 of the disconnected connectors.
  • Ignition switch: ON (engine stopped)

 Fully close the throttle valve with your finger
 0.3 - 0.7 V
Fully open the throttle valve with your finger
 4.0 V or more
31
 TPSS
 Throttle position sensor (sub)
  • Remove the intake air hose at the throttle body.
  • Disconnect the connector of the electronic-controlled throttle valve.
  • With the special tool test harness (MB991658) bridge only the mating terminals of No. 3, No. 4, No. 5, and No. 6 of the disconnected connectors.
  • Ignition switch: ON (engine stopped)

 Fully close the throttle valve with your finger
 4.0 V or more
Fully open the throttle valve with your finger
 1.0 V or less
42
 OPSW
 Engine oil pressure switch
 Ignition switch: ON
 1 V or less
Engine: Idle operation
 System voltage
48
 C/RL
 Throttle valve control servo relay
 Ignition switch: ON → LOCK (OFF)
 1.0 V or less → System voltage → 1.0 V or less
58
 RSB
 Power supply voltage applied to throttle valve control servo
 Ignition switch: ON
 System voltage
65
 P/S
 Power steering fluid pressure switch
 Engine: Idle operation after warm-up
 Steering wheel: stationary
 System voltage
Steering wheel: turning
 1 V or less
72
 FP/R
 Fuel pump relay
 Ignition switch: ON
 System voltage
Engine: Idle operation
 1 V or less
74
 AC/T
 Fin thermo sensor
 Evaporator surface temperature: 25°C (1.5 kΩ)
 1.1 - 1.3 V
77
 BACK
 Backup power supply
 Ignition switch: LOCK (OFF)
 System voltage
88
 AC/S
 Blower switch
  • Ignition switch: ON
  • Blower switch: OFF

 System voltage

  • Ignition switch: ON
  • Blower switch: ON

 0 - 3 V
89
 IGN
 Ignition switch - IG
 Ignition switch: ON
 System voltage
95
 AFS
 Air flow sensor
 Engine: Gradually increase the speed
 Voltage increase in response to racing
96
 AFS5
 Applied voltage to the air flow sensor
 Ignition switch: ON
 4.9 - 5.1 V
97
 ST
 Ignition switch - ST
 Engine: Cranking
 8 V or more
98
 STCD
 Starter active signal
 Engine: Cranking
 System voltage
Engine: Idle operation
 1 V or less
103
 STRL
 Starter relay
 Ignition switch: ON
 1 V or less
Engine: Cranking
 System voltage
104
 AC/R
 A/C compressor relay

  • Engine: Idle operation
  • Blower switch: OFF → ON
    (when the compressor is active)

 Battery voltage → 1 V or less
106
 BAT1
 Power supply
 Ignition switch: ON
 System voltage
108
 F/LO
 A/C condenser fan relay
 A/C condenser fan inactive state
 System voltage
A/C condenser fan rotation state
 1 V or less
110
 C/R
 Engine control relay
 Ignition switch: LOCK (OFF)
 System voltage
Ignition switch: ON
 1 V or less
111
 APSM
 Accelerator pedal position sensor (main)
 Ignition switch: ON
 Release the accelerator pedal
 0.9 - 1.1 V
Depress the accelerator pedal fully
 4.0 V or more
112
 APS5
 Applied voltage to the accelerator pedal position sensor (main)
 Ignition switch: ON
 4.9 - 5.1 V
123
 APSS
 Accelerator pedal position sensor (sub)
 Ignition switch: ON
 Release the accelerator pedal
 0.4 - 0.6 V
Depress the accelerator pedal fully
 2.0 V or more
124
 AP5
 Applied voltage to the accelerator pedal position sensor (sub)
 Ignition switch: ON
 4.9 - 5.1 V
note *1: The shown voltage is the average value where an analogue voltmeter is used (because a digital voltmeter may not be able to indicate the average voltage stably).

CHECK CHART FOR RESISTANCE AND CONTINUITY BETWEEN TERMINALS
1.Turn the ignition switch to "LOCK" (OFF) position.
2.Disconnect the engine-ECU connector.
3.Measure the resistance and check for continuity between the terminals of the engine-ECU harness-side connector while referring to the check chart.
note
  1. When measuring resistance and checking continuity, a harness for checking contact pin pressure should be used instead of inserting a test probe.
  2. Checking need not be carried out in the order given in the chart.
caution If the terminals that should be checked are mistaken, or if connector terminals are not correctly shorted to earth, damage may be caused to the vehicle wiring, sensors, engine-ECU and/or ohmmeter.
Be careful to prevent this!
4.If the ohmmeter shows any deviation from the standard value, check the corresponding sensor, actuator and related electrical wiring, and the repair or replace.
5.After repair or replacement, recheck with the ohmmeter to confirm that the repair or replacement has corrected the problem.


Terminal No.
 Terminal code
 Inspection Item
 Standard value, normal condition (Check condition)
1 - 2
 ETV+ - ETV-
 Throttle valve control servo
 0.3 - 80 Ω (at 20°C)
28 - 16
 WTS - E
 Engine coolant temperature sensor
 14 - 17 kΩ (at -20°C)
5.1 - 6.5 kΩ (at 0°C)
2.1 - 2.7 kΩ (at 20°C)
0.9 - 1.3 kΩ (at 40°C)
0.48 - 0.68 kΩ (at 60°C)
0.26 - 0.36 kΩ (at 80°C)
29 - 86
 ATS - AFSE
 Intake air temperature sensor
 13 - 18 kΩ (at -20°C)
5.3 - 6.7 kΩ (at 0°C)
2.3 - 3.0 kΩ (at 20°C)
0.30 - 0.45 kΩ (at 80°C)
3 - 106
 OHFL - BAT1
 Oxygen sensor (front) heater
4.5 - 8.0 Ω (at 20°C)
4 - 106
 OHRL - BAT1
 Oxygen sensor (rear) heater
 4.5 - 8.0 Ω (at 20°C)
11 - 106
 PURG - BAT1
 Purge control solenoid valve
 20 - 26 Ω (at 20°C)
59 - body earth
 RSG - body earth
 Engine-ECU earth
 Continuity (2 Ω or less)
119 - body earth
 GNDB - body earth
120 - body earth
 GNDE - body earth