Figure 1 measures the standard PT CAN waveform and reads the servo valve current during trial operation: 850 ~ 860 Ma at rest, 400 ~ 300 Ma at 50 ~ 100 km/h, and the current decreases as the speed increases. . In order to find out whether the fault was caused by the DS C and SVT modules, we unplugged the Servotronic solenoid valve during power steering. The test direction was slightly heavier, but it was definitely not without any power assistance. Insert the servo solenoid valve back. After several test runs, there is no DSC alarm, and there is no DSC related fault code in the IS ID detection. It appears the fault is centered on the mechanical power steering system.
Check whether the booster oil is dirty and smelly. The fault still exists after replacing the booster oil. Is the fault caused by a loose booster pump belt? When the fault occurred, we artificially tightened the belt of the booster pump, but the fault still existed. Now, the fault points are concentrated on the following components: fluid reservoir, power hose, steering gear. A booster pump is more likely. We disassembled the booster pump and found nothing unusual. Remove all booster tubes and blow them clean with compressed air.
The only thing left is the steering gear. First we reversed the servo solenoid and the fault persisted. We replaced the steering gear again and the problem was still the same. At this time, the fault became serious, the booster pump rattled, and the oil in the reservoir did not circulate. We ordered a new booster pump because the booster pump was damaged, and the problem persisted after installing the new pump. Reorganize your thoughts and check that the stored oil is not circulating. When there is power, the power oil starts to circulate.
Remove the oil inlet pipe and oil return pipe on the steering gear and find that the pressure in the oil inlet pipe is not high. Since there is no pressure gauge to measure the boosted oil pressure, try to plug it tightly by hand, and the oil return pipe will return oil normally. Is the booster oil bottle clogged? Removed the reservoir and replaced it with a clean coolant bottle, test failure persisted. Remove the high-pressure oil inlet pipe from the booster pump and block the oil outlet of the booster pump with your hands. I found that the pressure was very high and I couldn't stop it at all. It seems that the problem lies in the high pressure oil pipe from the boost pump to the steering gear. I found it impossible to blow high-pressure oil pipes with my mouth. Due to the shortage of high-pressure oil pipes, it was found during the processing that the core of the pipe was deformed and blocked, resulting in no pressure in the oil pipe, which was helpful for loading the oil pipe after processing. I thought the fault was solved, but it reappeared after several test runs.
Check whether the data flow of the engine is normal. The customer has not reported engine power problems, and the probability that the engine will not help is very small. Check whether the chassis suspension is normal. There is no obvious abnormality in the front of the car body. It is unlikely that the suspension and body data will cause no assistance. After installing the old booster pump, there is the booster. However, after many test runs, the fault still exists and the booster pump makes noisier than the new pump.
Disassemble the booster pump again and the impeller is normal. After disassembling the pressure limiting valve of the booster pump, it was found that the valve body of the booster pump was stuck. When the valve body was removed, it was found that the valve body itself had many scratches. The valve body was polished with fine sandpaper and installed on the retest vehicle. The booster returned to normal, but the booster pump made a little noise.
Disassembled the valve body of the new booster pump and found that the valve body also had some hairpins. The new valve body was polished, pressurized oil was added to the car, and the exhaust test run returned to normal. However, the booster pump is very noisy. Since the pressure limiting valve of the new booster pump is damaged, please order a new booster pump again.
@2019