According to the BDM Adapters full analysis of the phenomenon may be the cause of the malfunction: ① GTS diagnostic failure; ② DC3 connector power, ground or communication problems; ③ CAN line open or short circuit; ④ CAN bus or branch to power or ground short circuit; ⑤ combination instrument or Ktag V7.020 online internal fault; , Air conditioning amplifier, EPS ECU, SRS ECU, BCM body ECU and other CAN feeder controller related internal circuit failure.
Check and analyze a possible cause of the malfunction. Measure the voltage between pins 4 and 16 of DLC3 to 12.37V (the standard value is the battery voltage), no abnormalities; connect GTS to check DLC3 and check that CAN-H and CAN-L display "red (CAN-H) and E18-14 (CAN-L) resistance measurement of 1.3Ω (standard value: 54 ~ 69Ω), were measured E18-6 (CAN -H) and E18-14 (CAN-L) and the power supply, there is no short circuit between the ground; view maintenance manual, refer to the Vpecker E4 APP diagnosis CAN topology diagram, measuring ECM and body ECU terminal resistance are about 120Ω; The relevant ECU on the feeder line, and the E18-6 (CAN-H) and E18-14 (CAN-L) connected to the DLC3 at the same time, measured the resistance thereof and found that the resistance after disconnecting the ABS ECU was 2.0Ω : 54 to 69Ω) to indicate that there is a short circuit in the internal fault of the ECU or its connector. The resistance between the CAN-H and the Ktag V7.020 CAN-L in the DLC3 with the ABS connector reset and the body ECU disconnected is 2.9Ω (standard value: 69Ω), indicating that there are also short-circuit the body ECU; So at the same time disconnect the ABS ECU and body ECU, DLC3 CAN-H and CAN-L between the resistance of 61.7Ω (standard value: 54 ~ 69Ω); GTS diagnostic instrument can communicate with the vehicle, the instrument engine speed to return to normal.
ECU tunners tend to have both full BDM adapters and Led BDM frame:
BDM Frame with 4 Probes Mesh and LED Full Kit
another version of BDM Frame with 4 Probes Mesh and LED Full Kit
Remove the ABS ECU and the body ECU check, did not find any water or other substances into the internal short-circuit phenomenon; check the connector no corrosion, pin deformation and other signs; view the car before the state (Figure 2) Most of the body here ground line was broken, and the other part of the BDM Probe full adapters line without any exception, and this car did not install any boutique parts. From the above speculation, it should be due to the relevant ground circuit open circuit, making ABS ECU and body ECU internal circuit due to vpecker e4 app abnormal power input. Replace the ABS ECU and the body ECU (shown in Figure 3), loading, testing, vehicle system back to normal, troubleshooting.