Connect the indicator light wire, and check whether the indicator light is on or off under working conditions.
1. ST7126 is used to check the continuity of a single line. The indicator light is on and the circuit is normal. .
2. S17123 is used to check the solenoid valve assembly circuit (for proportional solenoid valve and directional solenoid valve).
(1) Proportional solenoid valve and walking speed selector solenoid valve. When the corresponding joystick or switch is working, the indicator light is on and the circuit is normal. :
(2) Rotary parking solenoid valve. When turning and/or retracting the stick, the indicator light is off and the circuit is normal. When the joystick is in neutral, the indicator light is on and the circuit is normal.
3. ST7130 is used to check the circuit of the swing buffer solenoid valve. When the rotary joystick is working, the indicator light is on and the circuit is normal.
4. ST7124 is used to check the pump displacement solenoid valve circuit (because the indicator light only lights up briefly, so be careful not to miss it). When the joystick is working, the indicator light is on and the circuit is normal (it is easier to check the working arm).
5. ST7125 is used to check EC motor circuit. When one of the power mode switches P, E, L or I is pressed, if the two indicator lights are on, the circuit is normal; if only one indicator is on, the circuit where the indicator is not lit is faulty; if the two indicators are on If the lights are not on, check the relays and wires.
6. ST7129 is used to check terminals 2 and 3 of EC sensor, A sensor and DP sensor.
7. ST7139
ST7139 light wire and ST7129 light wire are connected to the same connector (terminal 2), which is used to adjust the installation position of the A sensor. After connecting the S17139 light wire to the A sensor, open the switch (OFF), and the signal voltage becomes OV, so the pump displacement angle increases to the maximum. Then, turn the switch to ON, and adjust the installation position of the A sensor so that the signal voltage is equal to the specified signal voltage (4.4 + 0.05) V.
8. ST7127
It is used to check the emergency relay circuit (only for Isuzu engines), when the engine is difficult to start or stop.
(1) T lamp: check between terminals ACC and 4(T). The following states indicate that the ACC (power supply) is supplying current to the engine oil pressure switch: (a) When the engine oil pressure switch is turned on (ON) (the oil pressure is low at the time), the T light is turned on (ON).
(B) When the engine oil pressure switch is turned off (OFF), the T light is off (()FF) (slightly bright).
(2) ACC light: Check between terminals ACC and 3(E). The following states indicate that the ACC (power supply) is supplying current to the engine stop relay: (a) When the key switch is in the ON or START position, the ACC light is on. (b When the key switch is in the OFF position, the ACC light is off.
(3) PI lamp: check between terminals 2 (P1) and 3 (E). The following states indicate that the engine is stopped and the motor is in the fuel supply position: (a) When the engine is running (the key switch is on (ON> position), the P1 light is on. (b) When the engine is started (the key switch is in the START position) (E) When the engine is stopped (the key switch is in the OFF position), the P1 light is off.
(4) P2 lamp: Check between terminals 5(P2) and 3(E). The following states indicate that the engine is stopped and the motor is in the fuel cutoff (closed) position: (a) When the engine is stopped (the key switch is in the OFF position), the P2 light is on. (b) When the engine is started (the key switch is in the start position), the P2 light goes out. (c) When the engine is running (the key switch is in the ON position), the P2 light is off.
(5) P2' lamp: check between terminals 6 (P2') and 3 (E). The following states indicate that the engine stop (fuel cut) signal is sent from the emergency relay to the engine stop motor: (a) When the engine is stopped (the key switch is in the ON or OFF position), the P2' light is on. (b) When the key switch is in the HEAT, ACC or START position, the P2' light is off.
(6)c lamp: Check between terminals 1(c) and 3(E). The following states indicate that the engine start signal is sent from the key switch to the emergency relay: (a) When the key switch is in the START position, the C light is on. (b) When the key switch is in any position other than the starting position, the C light is off.
9. ST7128
It is used to check the engine stop motor circuit (only applicable to Isuzu engines), used when the engine is difficult to start or stop.
(1) A light: Check between terminals 1(A) and 5(E). The following states indicate that the engine stops and the motor drive signal is sent from the engine stop relay: (a) Start the engine, turn the key switch to the OFF position, and the A light is on.
(B) When the engine is stopped, turn the key switch to the START position, and the A light is on. (c) When the engine is running or stopped, the A light goes out.
(2) B light: check between terminals 3(B) and 5(E). Whenever the B light is on, it means that the battery voltage is supplied to the engine stop motor.
(3) P1 light: Check between terminals 4 (P1) and 5 (E). The following states indicate that the engine parking motor is in the fuel supply position: (a) When the engine is running (the key switch is in the ON position), the PI light is on. (b) When the engine is started (the key switch is in the START position), the P1 light is on. (c) When the engine is stopped (the key switch is in the OFF position), the P1 light is off.
(4) P2 lamp: Check between terminals 2 (P2) and 5 (E). The following states indicate that the engine parking motor is in the fuel cutoff (closed) position: (a) When the engine is stopped (the key switch is in the OFF position), the P2 light is on. (b) When the engine starts (the key switch is in the START position), the P2 light goes out.
