Experiencing a frustrating “no communication” error when trying to connect your OBD2 scanner to your 2007 BMW 328i Coupe? This is a common issue that can prevent you from diagnosing and resolving car problems. This guide provides a step-by-step approach to help you pinpoint the cause and potentially restore communication.
First, let’s start with the basics. Have you recently performed any work near the OBD II socket or the Junction Box Electronics (JBE)/JB Fuse Panel? Recent modifications or repairs in these areas could be the source of the issue.
Begin with a simple test. If you have access to a generic OBD II scan tool – the kind any auto parts store might use – try connecting it to your BMW. These basic scanners are designed to read engine ECU codes in any North American vehicle from 1996 onwards. Attempting to connect with a generic scanner will help determine if the issue is with your specific advanced scan tool or a more fundamental communication problem with the car itself.
If a generic scanner also fails to connect, the problem likely lies within your BMW’s communication system. A crucial initial check involves the Battery Guard (BG) cable and OBD2 port power. When you plug in a diagnostic cable, the BG cable should briefly light up for about one second. Furthermore, using a multimeter, verify you have 12V+ at Pin #16 of the OBD II socket at all times and at Pin #1 when the ignition is turned ON. These voltage checks confirm basic power supply to the OBD II port. If these checks pass, the issue may stem from the D-CAN (Diagnostic CAN) line.
To investigate the D-CAN line, the next step involves inspecting Connector X14271 at the JBE. Locate the blue connector on the JBE (typically on the driver’s side). Disconnect X14271 and carefully examine the pins and sockets for any signs of corrosion. Pay particular attention to Pin #33, as this is where the D-CAN line from Pin #7 of the OBD II socket (X19527) connects to the vehicle’s bus system at the JBE Bus Portal. Use a multimeter to confirm continuity between Pin #7 of the OBD II socket connector and Pin #33 of the X14271 connector.
For reference, here are wiring diagrams for the OBD II Socket (X19527) for 2007 BMW 328i Coupe models manufactured before 03/01/2007: https://www.newtis.info/tisv2/a/en/e90-328i-lim/components-connectors/plug-in-comb-type-solder-connectors/connectors-from-x1/x19527-x19527/oMMal4U
It’s important to note that BMW Junction Box Electronics (JBE) configurations changed around March 1, 2007. Connector X14271’s location might differ depending on your 2007 BMW 328i Coupe’s production date. For models produced before 03/01/2007, X14271 is typically on the inboard side of the JBE. For models produced after 03/01/2007, it’s usually on the outboard side. Refer to these TIS Installation Location diagrams to correctly identify X14271 in your vehicle:
- Before 03/01/2007 JBE Location: https://www.newtis.info/tisv2/a/en/e90-328i-lim/1VnYoJSPhH
- After 03/01/2007 JBE Location: https://www.newtis.info/tisv2/a/en/e90-328i-lim/G8ns32Rq
Pay attention to the orientation of the large fuses in the lower-right corner of the fuse panel in these diagrams to help identify the correct JBE layout for your 2007 BMW 328i Coupe.
This connector view diagram for X14271 should be applicable to both early (JBBF 70) and later (JBBF 87) JBE variants: https://www.newtis.info/tisv2/a/en/e90-328i-lim/CTHz9Js2
By systematically checking these points – from basic scanner compatibility and power supply to connector integrity and D-CAN line continuity – you can methodically troubleshoot the “no communication” issue with your OBD2 scanner on your 2007 BMW 328i Coupe. If these steps do not resolve the problem, it may be necessary to consult with a professional BMW technician for further diagnosis.
