Quote:
Originally Posted by GTRMagic
And, back at first principles, you identify the 20 things it could be, in components, and change them out one at a time, try again, to eliminate them as the source of the failure.
If the Mustang is a standard production car, wouldn’t pulling one off the dealer lot and facilitating this method of error elimination produce the desired result?
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Being a Ford you have to reprogram the replacement modules using Ford IDS software too.
For the most part you can't just swap modules in a CANBUS car, but rather you have to reprogram them to the vehicle.
A good auto-electrician who can backprobe and read CANBUS (digital) signals is invaluable!
Quote:
Originally Posted by johnh875
the same thing (effectively) happened with the BMW's when they started racing 15 years ago, plus others.
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Here's a BMW that refused to start because the door handle had a short circuit. Naturally it made sense to Hans who assumed the door handle would never become faulty, and hence it was perfectly reasonable for Hans to require a signal showing the door handle wasn't being opened as a condition for the car to start!
The video also gives a good example of the kind of diagnostics that can be carried out on a typical modern CANBUS vehicle with dozens of modules (there is nearly a module for every little feature the vehicle has, of course not all relevant for the drivetrain), and the digital signals that travel between the modules.
Sure, the good ol' test light it still invaluable too, but in the case of the BMW it went through multiple workshops before it reached someone who knew what they were doing.
Conversely, some car owners seem to place too much faith in the onboard diagnostics and think fault codes would give all the solutions, which is obviously not correct either.