Why it is not a good idea to introduce electronic upgrades to your brand new car? I’m talking of upgrades such as stereos or even light bulbs.
Even changing a battery has now become a bit of a challenge with new cars, and letting these new cars run out of batteries is a definite no-no.
Since 2003 car manufactures have been introducing (CAN) Control Area Network modules. CAN has made the electrical system in late model cars much more complicated than ever before. CAN allows various modules and systems to share data and interact with each other, something that was not possible before the digital age.
CAN is a communication standard that allows the various modules and computers in a vehicle to talk to one another via a common “data bus” circuit in the wiring system. It is a high communication line that allows data and commands to zip back and forth from one module to another. This allows the engine control unit (ECU), antilock brake/traction control/stability control system, electronic steering, electronic suspension, automatic climate control system, keyless entry system, lighting control modules and dozens of other systems and modules to all be interconnected electronically.
CAN communication data is sent digitally, meaning with 1s and 0s. These 1s and 0s are represented by voltage readings. Some cars come with +12 volts as the high and -12 volts as the low. All these communication is managed by what is known as a BIU Body Integrated Unit.
Thanks to CAN technology, new cars have so many features in the instrument cluster and the dashboard with very few wires. Again because the information is given digitally.
These communications between systems in the car must work harmoniously, therefore making voltage stability within the electrical system of the car very important. Changing any electronic device in the car that is not exactly the same spec as that of the car can cause a disturbance. For example the car is equipped originally with HID bulbs and it is replaced with LED bulbs, the electrical stability of the car can be affected and the car suddenly throws a code with the Malfunction Indicator Lamp blinking. Changing the stereo system or just even the speakers can bring some electrical noise that may interfere with the CAN communications.
I had a friend who was complaining that he can only change the battery of his car in the dealer because it has to be programmed by the dealer’s computer for the car to work properly. The main reason behind that is the CAN system. The modules in the CAN system require a certain amount of voltage for the memory settings. If this is lost, the module will forget these settings and may not function properly. This is why the dealer scan tool is necessary in replacing batteries of certain cars. My way around that is I keep the keys on accessories and plug a 12v battery on the lighter/power supply outlet (make sure polarity is correct so nothing gets fried). Then carefully remove the battery and carefully install the new one without grounding or shorting any of the wires. This way none of the modules are shut down in the battery replacement process.
Yes, cars are getting complicated.