Modern day vehicle diagnosis is a minefield. Just ask any Old School mechanic and with a tear in their eye and a faraway look on their face they’ll talk about points and carburetors and grease nipples.
Here at Van Der Veer’s we’re not intimidated by the modern, and enjoy the challenge of complex diagnosis; reading the runes of EOBD fault reads, checking network functionality, running test plans etc. You see, once you understand how a vehicle works, what information the various sensors can give you (and how limited it sometimes is), you will see that modern vehicles are, for the most part designed and built with a lot of common sense.
“For the most part…”
The exceptions can be bewildering and frustrating, and only occasionally cause our favourite Dutchman to launch into an unrecognisable language which doesn’t sound awfully polite. This blog post is about just one such occasion…
We took in a BMW M5 (F10) which presented with a lack of power, EML and gearbox warning light. An EOBD fault read showed us ‘No communication with DSC’.
We manually checked the DSC system and found that there was no power to DSC module from fuse 2. We replaced fuse 2 (5A) and the fuse failed immediately upon commencing a road test.
The next process was to test all the wiring for the DSC, which we did. All returned well, no apparent faults. We then decided to check what else was on fuse 2 and, after printing a wiring diagram, discovered that the four outer door handle controls for ‘comfort opening’ are on the same fuse. After a little bit of trial and error we discovered that the front passenger door handle had a faint smell of burning. We disconnected the door connection at the A-pillar, replaced the fuse and tested the system.
Everything worked perfectly. Then it was just a matter of replacing the faulty components in the door handle and everything could be re-connected.
However, it leaves the question burning in our minds…who in their right mind uses the same fuse to control driving safety features, and a comfort option? I wonder how much has been spent on diagnosing this fault elsewhere?
We’d appreciate your feedback if you have experienced anything similar with your BMW.