Symptom: BMW M3 for the two-door sports car, the car in the engine running, the dashboard of the yellow ABS warning light is still in a bright state.
    Fault diagnosis: As the BMW GTl original diagnostic instrument without M models for the election, so use the AST diagnostic device for self-diagnosis, in the ABS control module diagnostic menu, select "GetFau" function, query fault information, showing three failures code. To confirm the authenticity of the fault content. Select "ResetFau" function, clear the contents of the fault code, and then re-query the fault information. Only one fault code:
    17FauItinthepowersIJpplyt0allsolerlOidvalvesOrirltakevalve (frontleft) notworkingproperIy.
    Meaning for all solenoid valve power supply failure or left front oil solenoid valve does not work properly.
    Fault code involved in the solenoid valve, refers to the ABS control module assembly in the brake cylinder of the inlet and outlet solenoid valve, according to the meaning of the fault content. Very intuitive to think of the biggest possibility is the power side of the problem. Open the fuse cover on the left rear of the engine compartment. Measure the fuse 10, 22, and 34 of ABS electric control system. normal. In addition, in the fuse box. There are many relays. Which has two marked with ABS mark, it is estimated that ABS hydraulic electric pump and solenoid valve used. After a preliminary inspection. Gray for ABS hydraulic electric pump relay, red for ABS solenoid valve relay. Is one of the most common ABS system power supply.
    Open the red solenoid valve relay housing. Check inside the contact switch status. No signs of ablation, measurement control coil resistance is 90Ω, within the standard range. Replace the solenoid valve relay and turn on the ignition switch. At this point you can see the relay contacts pull O5s after the disconnect, which shows that the ABS control module on the control of the relay, as to why the bounce after bounce, the system should be monitored after the failure of the circuit failure protection. The next test work. It is necessary to measure the power output of the relay.
    ABS control module is located below the vacuum booster, the entire hydraulic unit uses only a circular harness connector, which includes the hydraulic electric pump and solenoid valve and other electrical components lines. Unscrew the plug. Can be seen for 12-pin form. In order to find the plug in the solenoid valve relay power supply pin, press the solenoid valve relay contact method, and then use the test lamp on the plug of the pin to measure and identify. The results measured No. 3 for the solenoid valve power supply pin. Then open the ignition switch to test, you can see the test light O. 5s after extinguishing. Indicating that the relay is properly connected to the harness connector of the control module. At this point. Has been able to determine the failure within the control module.
 Subsequent work is through the plug pin between the resistance measurement, the parameters of the solenoid valve to do qualitative check. In order to figure out the actual function of each pin. (2-pin), solenoid valve power supply (2-pin) and 6 solenoid valves (6-pin), hydraulic electric pump (2-pin), hydraulic electric pump speed sensor (2-pin) Used. The car's ABS hydraulic tubing is controlled in three-channel form. So the six solenoid valves are: left into the oil solenoid valve, left front oil solenoid valve, right front oil solenoid valve, right front oil discharge solenoid valve, rear oil into the solenoid valve, rear wheel oil discharge solenoid valve. After the actual measurement, the plug between the 3 and 2 pin resistance (left front oil solenoid valve) is 320kQ. 3 and 1 pin resistance (right front oil solenoid valve) is infinite, the rest of the relevant pin resistance value of 6.2Ω, which proves the left front, right front oil solenoid valve failure.
    To further determine whether the fault is in the solenoid valve itself. Alternative tests were carried out using simulated methods. In the plug of the 3 and 2 pins asked in parallel with a test light. Turn on the ignition switch. Use the AST Diagnostics to clear the fault code, and then re-check the fault letter. 17 fault code disappeared, replaced by the 20 fault code:
    20Operationoffrontrightinletvalvefaulty meaning for the right front oil solenoid valve control failure, which also verify the correctness of the previous measurement work. Using the same method. In the plug between the 3 and 1 pin in parallel between a test light, open the ignition switch and run the engine, the dashboard of the ABS warning light goes out, thus, in the BMW M3 models used ABS electronic control system, as long as the exclusion of the Fault problem, no need to clear the memory fault code, ABS system will be able to work properly. At this point. Has been fully able to determine the fault is due to the left front oil solenoid valve and the right front oil solenoid valve damage caused. Replace the new ABS control module assembly, troubleshooting.