Why is the Geely Vision completely out of power after it stalls while driving?

Fault phenomenon: A 2009 Geely Vision 1.8L sedan, equipped with a CVVT engine, with a mileage of 25,000 km. The user reported that the car suddenly stalled while driving and the whole car ran out of power.

Inspection and analysis: According to the fault phenomenon, the author analyzes the following reasons for this situation.

① The battery pins fall off, the main fuse burns out, and the battery itself fails.

② The charging system control circuit fails, and the generator fuse burns out.

③ The generator tape slips or falls off.

④ The generator is open or short-circuited.

⑤ The output part of the charging system fails.

The author eliminates the above situations one by one, checks the main fuse, which is normal; checks the battery terminals, and the connection is normal; checks the battery voltage, which is 4.2 V, which is seriously depleted. Charge the battery. In order to confirm the cause of the fault as soon as possible, the author finds a battery of the same model that is confirmed to be intact and installs it on the vehicle for further inspection. At this time, the vehicle was started, the engine ran normally, the charging indicator light was not on, and the measured power generation voltage was 12.1 V, which was obviously too low, and the generator might not generate electricity. When the engine speed was increased to 2 000 r/min, the measured power generation voltage did not rise, but showed a downward trend. Therefore, it was preliminarily determined that the generator was not generating electricity.

The main reasons for the generator not generating electricity include faults in the generator, related accessories and circuits. The author first checked the generator tape to confirm that it was installed correctly, the tension was normal, and there were no abnormal wear marks; then measured the generator control circuit, unplugged the plug to measure each terminal, and the normal power supply, ignition switch control power supply and charging indicator control line were all normal; then plugged in the plug and started the engine, and measured the generator output voltage of 0 V. Could it be that the generator itself was faulty? However, when measuring the connection line between the generator and the battery, it was found that the line was in an open circuit state.

Since two doubts appeared at the same time, the author eliminated them one by one according to the principle of starting from the simple to the complex. First, use a jumper wire to directly connect the generator output terminal to the positive battery line, then start the engine, and measure the power generation voltage of 14.2 V, which returned to normal. It can be concluded that the problem lies in the connection line from the generator to the battery. According to the data, there is a connector for this line in the fuse box in the engine compartment, so the author opened the fuse box to check, found the yellow plug connector of the line, unplugged the plug connector for inspection, and found that it was severely burned (Figure 1), so the cause of the fault was found.

Figure 1

Troubleshooting: Since the manufacturer does not provide this plug connector accessory separately, the engine compartment wiring harness assembly needs to be replaced. Considering that the user is eager to use the car and the problem is not very serious, the author decided to manually repair the plug connector. Disassemble the fuse box, remove the original plug connector of the charging connection line, install a copper connector and fix it firmly with solder, then lead the copper connector to the lower part of the fuse box for proper treatment and fixation (Figure 2), complete the above operations and test drive, the fault was eliminated.

Figure 2

Review and summary: When the generator output terminal is found to have no voltage, maintenance personnel generally think that the problem lies in the generator itself. However, the generator of this model adopts circuit protection control. When the generator output is disconnected from the positive pole of the battery or short-circuited with other circuits, the voltage output will be automatically cut off to protect the vehicle body circuit and the generator itself. Therefore, maintenance personnel must perform more measurements and tests during work and do not replace accessories blindly. When repairing vehicles, you should be open-minded and pay attention to every detail in the detection process. This fault is limited to vehicles produced before October 2008. Vehicles manufactured after October 2008 have been improved to bolt and nut connection here (Figure 3).