Overview
A New Zealand distributor contacted Opus IVS during a live demo regarding a customer experiencing remote central locking issues on a BMW 3 Series E91. With no fault codes present and the issue ongoing, the case was escalated to the Opus IVS Team.
Chris Routledge, General Manager for Australia and a former BMW Master Technician, supported the distributor and their new customer. Drawing on his BMW background, Chris guided them through a successful diagnosis and repair.
Symptoms
Remote central locking is not functioning via the key fob, but it is fine with the central locking button in the car.
No fault codes stored in the vehicle’s systems
Root Cause Identified
Broken wiring inside the loom running through the boot lid hinge, between the CAS Module and the Diversity Amplifier Module.
Diagnostic Process
Chris guided the distributor through a structured diagnostic approach:
• Access the Diversity Aerial Module under the boot spoiler and inspect for water ingress.
• Inspect wiring and connectors using BMW wiring diagrams to confirm integrity.
• Check power supply to the module:
• Pin 6 (Red/Green) showed a correct 12-volt supply.
• Verify key fob signal reception:
• Tested Pin 3 (Blue/Red) with a multimeter while pressing lock/unlock on the key fob.
• The Frequency changed, confirming the Diversity Amp was receiving the key signal.
• If no signal had been present, this would indicate a fault with the key or the Diversity Amp.
• Checked the signal at the CAS (Car Access System) Module Pin 33
• No signal was detected at Pin 33.
• When the Diversity Amp receives the signal, but the CAS does not, this suggests a wiring break or short between the modules.
• If the CAS receives the signal but the vehicle still does not unlock, the issue lies within the CAS module itself.
Outcome
Following the diagnostic steps with both the distributor and their new customer, the issue was confirmed to be wiring damage within the boot hinge area. After exposing and repairing the damaged wiring, the remote central locking functionality was fully restored.
This successful fix not only resolved a complex customer concern but also showcased the value of expert remote support from Opus IVS. It was also a full-circle moment for Chris, revisiting a familiar BMW issue from earlier in his technical career.