Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
General Information
The vehicles electrical system consist of a number of control modules on the CAN and MOST network. The functions of the vehicle can be divided between the different control modules in the vehicle. The vehicles different functions are implemented via the CAN and MOST network. Each control module is loaded with software that executes functions and monitors the control module through integrated diagnostics.
Incorrect or failed functions in the vehicle usually depend on hardware faults, for example, contact play, oxidation, breakages or short-circuiting.
Software is not worn out and its function is not impaired overtime, however, unforeseeable behavior can occur in software which means it needs to be upgraded. It may also be necessary to upgrade software on account of legislation or when moving to another market.
When starting the control module the primary bootloader starts (PBL) for 20 ms (0.02 seconds). Should the control module receive a programming command (prog) during these 20 ms the control module enters programming mode.
The programming command is sent for approximately 2 seconds so that all control modules have time to execute the command and enter programming mode. If no programming command is sent the control module's application software takes over the function of the control module.
If a reset command is sent to the control modules in programming mode, the control modules will enter normal operating mode.
The primary bootloader means it is always possible for a control module to enter programming mode even if the application software has been corrupted, for example, during unsuccessful downloading.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.