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Coachman Online: How Can The Car Start When The Signal Is Gone?

The diesel engine can’t start, which is commonly known as can’t start, can’t start, can’t start, and so on. The names vary from place to place. Today, I share with you a fault that can occasionally and can’t live or die. It’s difficult to do business at this stage. Drivers know what fault codes their cars have before and repair them selectively. Many fault codes have nothing to do with the current phenomenon, so the driver requires some fault codes not to be handled to save costs. Now let’s talk about the content of this case in detail.

Model: Jiefang J6

Engine: Xichai 6dm2

Emission standard: Guosi

Electric control system: Bosch high voltage common rail



Fault Phenomenon Of The Signal:

A series of problems, such as difficult starting, shaking at idle speed, starting and stalling, and a sense of frustration during driving of the signal.

Coachman Online How Can The Car Start When The Signal Is Gone

It’s a classic Jiefang series tractor. I believe many friends have repaired it. The car had occasional starting difficulties half a month ago. A week ago, the crankshaft sensor and camshaft sensor were tested and repaired in other places where the oil pump was calibrated. The driver reported that there were frequent starting difficulties in the last two days. Sometimes it took seven or eight times to start, the car was stopped, and occasionally the battery didn’t run out of power, After chatting with the driver, I’ll plug in the artifact – the coachman C80 diagnostic instrument (mobile phone version, the driver doesn’t know what’s going on, the fault codes are read out, how to repair, and I know how much money to pay) I don’t say much nonsense, as shown in the figure above of the signal

Coachman Online How Can The Car Start When The Signal Is Gone (2)

Fault Phenomenon:

There are 7 fault codes in total, and only the seventh one affects the current fault phenomenon through visual inspection. Why? Pay more attention to the coachman online and watch more live broadcasts! When multiple vehicle fault codes exist, it is necessary to consider whether the fault code affects the current fault phenomenon of the signal.

For example, the fault code of short circuit to ground at the driving end of intake air preheating will not affect the startup, so it will not be handled temporarily. First solve the fault phenomenon and obtain the trust of the driver, and then deal with the unimportant fault.

Troubleshooting Process:

Deal with the seventh fault – no camshaft signal is detected. This fault code clearly indicates that there is a problem with the camshaft position signal, and the ECU does not receive the camshaft position signal. When the sensor was removed, the problem was seen at a glance. The repairman was careless and only tightened the screws. The sensor was deformed because the rubber ring was too tight and was not installed in place.

Coachman Online How Can The Car Start When The Signal Is Gone (3)

After the new sensor is replaced and installed correctly, the test run, the engine starts smoothly, the acceleration is strong, and the fault is eliminated of the signal.

After the car is repaired, let’s learn the working principle of camshaft sensor.

Coachman Online How Can The Car Start When The Signal Is Gone (4)
  • The magnetic field sent by the permanent magnet is transmitted to the signal tooth through the soft iron core, and the strength of the magnetic field is affected by the magnetic gap between the signal tooth and the sensor (the magnetic resistance changes).
  • When the signal tooth approaches the sensor, the magnetic field becomes stronger and smaller when it is far away. Therefore, when the signal tooth rotates, an alternating magnetic field will be generated, so that the electromagnetic coil will produce a sinusoidal induced voltage.
  • Therefore, the proper clearance is required for the normal operation of the sensor. Theoretically, it is less than 2mm. If the magnetic field is too large and weak, it will collide if it is too small. However, due to the processing technology of the signal panel and other reasons, we must make the sensor close to 1mm in maintenance, and the permanent magnet in the middle is in the middle of the mounting hole to ensure that the sensor works well. If it is too small, shims can be added, and if it is too large, the sensor can be ground, The sensor mounting shell can well solve the fault. As the saying goes, a folk prescription can cure all diseases.


We must fully understand the synchronization signal during maintenance. In short, the synchronization signal is the way for ECU to correctly identify the top dead center of cylinder 1 compression. The electronically controlled engine cannot physically obtain the injection time. Only by obtaining the accurate synchronization signal can we know when to inject fuel, how many cylinders to inject fuel in advance.

Therefore, the synchronization signal will affect the starting and normal operation of the engine, and a series of phenomena such as stopping the car will be caused when the sensor signal is poor. Welcome to leave a message below and learn more strange faults related to synchronization.

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