Thinkcar Diagnostic Case Study
2016 Range Rover Evoque Convertible – Intermittent CAN Network Communication Fault
Bob Shervill at RMS Diagnostics used the Thinkcar 399, CAN network testing, oscilloscope analysis and JLR wiring information to narrow a vehicle-wide intermittent communication fault to the rear differential control module/circuit.
| Vehicle | 2016 Range Rover Evoque Convertible |
|---|---|
| Customer complaint | Intermittent module communication, abnormal ignition operation and rotary gear selector faults |
| Diagnostic tool | Thinkcar 399 |
| Control system | High-speed CAN network |
| Stored fault code | Multiple intermittent communication faults across the vehicle – no single DTC identified the root cause |
| Key live-data finding | Module communication changed between scans and became stable when sections of the CAN network were physically isolated |
| Root cause | Fault isolated to the rear differential control module/circuit |
| Repair | Affected CAN section isolated for confirmation; rear differential module/circuit identified for final component-level checks |
| Outcome | Stable CAN communication, correct ignition operation and normal rotary gear selector operation restored with the affected circuit isolated |
Range Rover Evoque CAN Network Fault – Customer Complaint
The vehicle had been purchased by a car dealer at auction and had reportedly driven through the auction normally. By the following day, however, it could no longer be moved correctly.
The ignition would switch on but would not immediately switch back off. The rotary gear selector remained raised and, immediately after the ignition was switched on, it would only respond for one or two seconds before becoming unresponsive. The engine would start and run, but the rev counter was not operating normally and several systems were not providing normal feedback.
Initial Assessment
The symptoms initially made an aftermarket CAN-based immobiliser a reasonable possibility. Ghost-style immobilisers and similar systems can be hidden within vehicle wiring and communicate directly through the CAN network. Common installation areas were inspected, but nothing was found. The previous owner later confirmed that no Ghost immobiliser had been fitted.
Full Vehicle Scan with the Thinkcar 399
The Thinkcar 399 was connected and repeated full-system scans were carried out. The topology view gave Bob a clear overview of which modules were communicating, which were reporting faults and which were disappearing from the network.
Multiple intermittent communication faults across several control modules
Status: Intermittent / inconsistent network communication
The scan results changed from one attempt to the next. That indicated that many of the modules showing faults were likely victims of the network disturbance rather than the root cause.
Thinkcar 399 Data and Physical Testing Reveal the Fault Direction
One of the strongest clues was the difference between the vehicle with the ignition switched off and switched on. With the ignition off, several modules communicated normally. Switch the ignition on and communication became unstable.
CAN termination resistance measured approximately 60 ohms, which was correct, and there were no obvious shorts to earth. An oscilloscope was then connected to inspect network activity directly.
What Caused the Fault?
At this stage, the diagnostic question changed from “Which module is faulty?” to “What happens if we remove half of the network?” Using the JLR wiring diagram, Bob identified CAN junction points where large sections of the network could be isolated.
Sections of the original network were temporarily bypassed while maintaining the required termination. Once the affected section was removed, the ignition began switching correctly, the hazard indication behaved normally and diagnostic communication became stable. The network was then rebuilt section by section until the remaining circuit led to the rear differential control module.
Repair and Confirmation
With the rear differential control module disconnected and the remainder of the vehicle returned to its original network configuration, the vehicle remained stable. Diagnostic communication returned, the ignition operated correctly, the instrument cluster communicated normally and the rotary gear selector returned to normal operation.
The testing isolated the problem to the rear differential control module/circuit. The module itself should not automatically be replaced without first confirming its power supplies, earths, connector condition and associated wiring.
Scan → Analyse → Test the CAN Network → Divide the Network → Reconnect → Prove the Fault
How the Thinkcar 399 Helped Diagnose This Range Rover Evoque
The Thinkcar 399 was used repeatedly to monitor module communication while different sections of the physical CAN network were isolated and reconnected. That allowed Bob to compare the vehicle's behaviour directly with the network configuration.
The scan tool showed what the vehicle was reporting, the oscilloscope showed what was happening electrically, and the wiring diagram showed how the network was constructed. The diagnosis came from combining those pieces of evidence rather than relying on fault codes alone.
Scan → Analyse → Live Data → Prove the Fault → Repair → Retest
The Thinkcar 391, 393, 394 and 399 are capable of online Jaguar Land Rover functions, giving independent workshops additional manufacturer-specific capability when working on Jaguar, Land Rover and Range Rover vehicles.
Quick Answer: Why Did This Range Rover Evoque Lose CAN Communication?
The intermittent communication fault was narrowed down to the rear differential control module/circuit. When that section of the network was disconnected, CAN communication became stable, the ignition operated correctly and the rotary gear selector returned to normal operation.
The key diagnostic breakthrough was physically dividing the CAN network, creating a known-good section and then progressively reconnecting the network until the remaining fault area identified itself.
Frequently Asked Questions
Can a CAN network still be faulty if it measures 60 ohms?
Yes. Approximately 60 ohms confirms the expected termination resistance, but it does not prove that every connected module is transmitting or communicating correctly.
Why did different modules appear on different Thinkcar scans?
The intermittent network disturbance affected communication across multiple control modules. Modules could therefore appear during one scan and disappear during another without those modules themselves necessarily being faulty.
What diagnostic tool was used on this Range Rover Evoque?
Bob Shervill at RMS Diagnostics used the Thinkcar 399 for repeated full-system scans and communication checks throughout the diagnosis.
Which Thinkcar tools are capable of online JLR functions?
The Thinkcar 391, 393, 394 and 399 are capable of online Jaguar Land Rover functions.
Did the diagnosis prove that the rear differential module itself was faulty?
The testing isolated the fault to the rear differential control module/circuit. Further checks of the module, wiring, connector, power supplies and earths would be required before condemning the module itself.
