NOVEMBER 2023 AFTERMARKET 27 network so it could not talk back and forth. Alternatively, we had a short to ground pulling both circuits low causing the lack of signals. This could be quickly proven with one of my favourite tools, a test lamp. If I connect my test lamp to battery positive and connect to each pin one at a time and they are indeed shorted to ground my test lamp will light as the ground will complete the circuit. If they don’t, I most likely have a wiring issue which can then be tested with the multimeter.Using a test lamp is a safe way to do this as the bulb limits the amount of current flow allowed to flow in the circuit. Connecting my test lamp up to pin 16 on the breakout box and one at a time to pins 6 and 14 lit the bulb showing I did indeed have a short to ground and the cause of all the issues the vehicle was experiencing. Pin 16 is battery positive, which makes a handy testing spot saving running cables out to the battery itself. With this information I had now confirmed the network fault and could then set about tracking down the cause. This is where having the network topology and wiring diagram connectors was a must as I could split the circuit into chunks and test a piece at a time to narrow down the fault. Studying the diagrams showed several connectors inside and outside the vehicle. I decided to start with one near the front which would eliminate the wiring and modules under the bonnet. Leaving my test lamp connected allowed a good visual indicator if I removed the short from the circuit. I just had to be careful I didn’t unknowingly open circuit the wiring to the DLC which would also put the light out and lead me on a wild goose chase. Diagrams again Splitting the circuit at each test point one by one did not make any difference so it was back to studying the diagrams again. I then found a point in the diagram labelled license lamp. Like me, I am sure you are thinking what has a license lamp got to do with the CAN bus system? I decided to look into this and upon opening the connector information it showed the rear view camera in the tailgate used the high speed network. Why it was labelled license lamp I do not know. I guess that is a question for Hyundai. The technical information showed a connector at the rear of the roof lining very close to the rear interior lamp. After looking at what was involved to gain access to the camera itself, it was quicker and easier to drop the roof lining and disconnect the multi plug there. Upon gaining access and removing the connector my test lamp had now gone out. Please refer to Fig.2. Bingo! I had found my short. Restarting the car and checking my breakout box I now had flashing lights on pins 6 and 14. Connecting up the scan tool and attempting a global fault scan, I now had full communication with the entire vehicle, which allowed all the fault codes to be deleted and cleared the dash of all the warning lights. Trying the handbrake, it now released and it was decided to drive the vehicle back to the workshop to access tools to remove the interior tailgate panel to carry out the final tests to confirm the camera was indeed at fault and it was not a wiring issue. Upon removing the tailgate panel and exterior plinth to access the camera itself, it transpired that the camera was badly corroded and wet having suffered water ingress. Please refer to Fig.3. Reconnecting the wiring loom and disconnecting at the camera connector showed communication was still present, I then checked wiring at the connector and found everything to be as it should proving the fault was within the camera itself. In the end it was the rear camera shutting down the car, preventing it from driving. Interestingly, the engine started and ran so this must be due to the way Hyundai have configured the network as with some manufacturers this does not happen. I have also noticed that other manufacturers run the camera on a lower speed network so if this happened the vehicle would still be usable. It would just display different symptoms such as blank reversing screen or a fault message on the dash. This job shows that a seemingly complex fault can be simplified down in to bite-size chunks with a solid process, test plan, manufacturer technical and wiring information, and then quickly and accurately diagnosed. Fig. 2 www.aftermarketonline.net Fig. 3 Fig. 1
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