In the TICS fuel injection pump electronic control system, ECU (engine control unit) has a fault self-diagnosis function, which can detect the working conditions of each part of the control system. When the ECU detects the fault signals from the sensors and actuators, it immediately lights up the “CHECKENGINE” (check engine, also called fault self-diagnostic lamp) warning light, and stores the fault information in the memory in the form of a fault code.
The following focuses on how to use the fault code to diagnose and troubleshoot.
1. Retrieve diagnostic trouble code (DTC)
Retrieving fault codes to diagnose electronic control system faults is a very important basic method for repairing modern construction machinery. Usually, the code switch (fault self-diagnosis switch) will flash the “CHECKENGINE” warning light to read the fault code. The fault code retrieval method is as follows:
(1) Check whether the memory connector is closed.
(2) Turn off the start switch and turn it on again, but do not start the engine.
(3) Connect the memory code switch. The memory code switch is the blue connector on the lower left side of the dashboard,
(4) The “CHECK ENGINE” fault light on the dashboard flashes, and the fault codes are displayed in the order of the faults.
2. Read diagnostic trouble code
Three different flashing numbers indicate the code starting from three digits, and two different flashing numbers indicate the code starting from two digits. The flashing code word can be used to identify the diagnosis trouble code. When there are multiple diagnosis trouble codes, after one diagnosis trouble code is repeated 3 times, it will go to the next diagnosis trouble code. The diagnostic fault codes of the 6HK1-TC engine are shown in the attached table.
The backup control in the attached table is the safety insurance or “home” function provided by the TICS fuel injection pump electronic control system. When the ECU detects a sensor or circuit failure, it will control the engine to enter the forced operation state according to the program and data originally set by the ECU Or downtime.
3. Clear diagnostic trouble code
According to the prompt of the fault code, after the fault is eliminated, although the “CHECKENGINE” warning light has been extinguished, the fault information is still stored in the memory of the ECU and cannot be automatically eliminated as the fault is eliminated. Therefore, after troubleshooting, the fault code stored in the memory should also be cleared to avoid being mixed with the newly generated fault information and causing difficulties for the next maintenance. The procedure for clearing fault codes is as follows:
(1) Check whether the memory connector is closed.
(2) Turn off the start switch, and then turn it on again.
(3) Connect the memory clear switch for 1s. The memory clear switch is the white connector on the lower left side of the dashboard,
(4) Disconnect the memory connector and clear the memory 0.5 s after disconnection.
(5) Turn off the start switch and turn it on again, and check whether the diagnostic trouble code is cleared. If it still exists, repeat the above steps (1) to (4).
4. Precautions for use and maintenance
(1) When jumping to start other vehicles or use other vehicles to bridge the machine, the ignition switch should be turned off before the jumper can be disassembled.
(2) After the fuel injection pump is installed, the fuel injection pump can be started after exhausting the air, otherwise the pre-stroke actuator may be easily burned out.
(3) When moving the pump, do not carry the wiring harness or electrical components to prevent damage.
(4) Do not open the computer cover during maintenance, because the computer cannot be repaired even if it is broken, and it is likely to damage the computer after opening.
(5) It is strictly forbidden to disconnect the battery from the circuit when the engine is running at high speed to prevent transient overvoltage from damaging the computer and sensors.
(6) When the engine electronic control system fails, the CHECKENGINE warning light (CHECKENGINE) lights up, and the ECU stores the fault information in the memory, so the battery cannot be disconnected from the circuit to prevent the fault stored in the computer The code and related data information are cleared. The battery can be disconnected from the circuit only after the fault code and related information are called out through the fault self-diagnosis system and the cause of the fault is diagnosed.
5. Fault diagnosis case
(1) The engine cannot be started
Check: Recall the fault code to find out 6 fault codes, which are 01, 571, 423, 543, 29, 292. After the code is cleared, there are 2 fault codes (01 and 292) remaining. 01 is normal, 292 is the pre-stroke learning function error. After inspection, the resistance value of the 6 terminals of the “pre-stroke actuator” socket (6-pin gray) is normal, indicating that the pre-stroke actuator is good under static conditions, but there is no oil spray from the high-pressure oil pipe.
Analysis: There are two possibilities for high-pressure fuel pipes without fuel injection: one is that the ECU controls the electronic governor to cut off the fuel; the other is that the rack is stuck in the fuel stop (flame) position.
After removing the disassembly of the TICS fuel injection pump, it was found that the timing plate of cylinder IV and the pin on the timing rod were broken, and the timing rod was mechanically stuck in the fuel stop position. After processing and repairing and adjusting the fuel injection pump, the fault disappeared.
(2) The engine cannot be started
Check: Recall the fault code to find out a fault code, which are 01, 10, 423, 543, 292. After the code is cleared, there are 2 enemy fault codes (01 and 10) remaining. 01 is normal, 10 is rack position sensor error. The resistance value of the three terminals of the rack position sensor socket (3-pin white) is normal, but the output voltage of the ECU connector terminal is measured to be 3 V (normal value is 4.75~5.25V), and there is no oil spray from the high-pressure oil pipe.
Analysis: The output voltage of the ECU connector terminal is abnormal, and the high-pressure fuel pipe has no oil spray, indicating that the ECU is broken and the electronic governor is in a fuel cut off state.
Remedy: Replace the ECU, the fault disappears, and the engine works normally.
Note: Most of the failures of the electronic control system lie in the components, wiring, connectors and sensors of the system, and the ECU itself rarely fails.
(3) The engine cannot be started
Check: Recall the fault code to find out 3 fault codes, which are 01, 14 and 15, 01 is normal. The two fault codes 14 and 15 appear at the same time, indicating that the main speed sensor and the auxiliary speed sensor are wrong. Check the main speed sensor and the auxiliary speed sensor, and found a lot of oil stains.
Analysis: The main speed sensor and the auxiliary speed sensor have no pulses after serious oil pollution, and the ECU controls the electronic governor to cut off the fuel.
Remedy: Wipe and clean the main speed sensor and the auxiliary speed sensor, and the fault disappears.
(4) When the engine speed is increased to about 2 000 r/min, the speed cannot be increased any more, the operation is weak and the action is slow, and a lot of black smoke
Check: Recall the fault code to find out 2 fault codes, respectively 01 and 2920 01 are normal, 292 is the pre-stroke learning function error. After the circuit test, the resistance value of the 6 terminals of the “pre-stroke actuator” socket is abnormal, indicating that the pre-stroke actuator is damaged.
Analysis: If the pre-stroke actuator is damaged. The injection rate and the injection advance angle will be controlled in a standby mode, which can only maintain the engine running but cannot achieve the best performance.
Remedy: Replace the pre-stroke actuator, the engine power is restored, and the construction machinery operates normally.
(5) The engine is running weak, and a lot of black smoke is emitted
Check: Recall the fault code and check out 5 fault codes, which are 01, 29, 291, 423 and 292. 01 is normal: 29 is the pre-stroke servo system error; 291 is the pre-stroke sensor error; 423 is the pre-stroke power supply The fuse is blown; 292 is an error in the pre-stroke learning function. It can be seen that the faults are all related to the pre-stroke. After the circuit test, the 6 terminals of the “pre-stroke actuator” socket are all short-circuited, indicating that the pre-stroke actuator has been damaged.
Analysis: The short circuit of the pre-stroke actuator circuit is often caused by the exhaustion of fuel or the failure to exhaust air after the re-injection pump is installed, which causes the pre-stroke actuator to overheat.
Remedy: Replace the pre-stroke actuator, and troubleshoot.
(6) Sometimes the engine stalls by itself
Check: Recall the fault code and check out 3 fault codes, which are 01, 33 and 292. 01 is normal; 33 is the random access memory circuit error; 292 is the pre-stroke learning function error. After circuit testing, the resistance values of the 6 terminals of the “pre-stroke actuator” socket are all normal, indicating that the pre-stroke actuator is good under static conditions.
Analysis: The pre-stroke actuator is normal under static state, but it cannot be guaranteed to be normal under dynamic (working state). Because it is under the control of the ECU when it is working, if the ECU has an error, the pre-stroke control will be chaotic, and flameout will occur randomly when the engine is under load.
Remedy: Replace the ECU and the engine works normally.
(7) The engine is running weak, and a lot of white smoke is emitted
Check: Recall the fault code for query, and the engine has no fault code storage.
Analysis: If there is no fault code storage, the engine is weak and white smoke is emitted, it means that there is a problem with the mixture concentration and ignition timing, which is often caused by the fusing of the engine control unit