Milligan Auto Diagnostics tackles elusive chassis and powertrain CAN bus faults on a Discovery Sport and a Range Rover Evoque.
The first job, a Discovery Sport, presented with an inactive chassis CAN network. By monitoring with an oscilloscope while manipulating the loom, the technician found the blue and green CAN wires were shorting against the frame behind a damaged connector.
Referencing Hella Gutmann HGS Data diagrams, the gateway pins were traced to the compromised connector. Stripping, repairing, and re-taping the harness successfully restored communication to all chassis modules, allowing all DTCs to clear.
On a Range Rover Evoque with an intermittent powertrain CAN fault, a breakout box was connected to OBD pins 12 and 13. Monitoring the high-speed network with an oscilloscope revealed that turning the steering wheel slightly caused the signal to collapse into a “spaghetti” pattern.
A visual inspection revealed the harness was chafing against the steering column universal joint. The moving knuckle had rubbed through the insulation, shorting out the CAN bus. Repairing the wire and routing it securely away from the steering shaft resolved the fault.
