MAKING ALL THEWRONG CONNECTIONS...
Take a good, hard look at the largest of the half-dozen pictures below. It shows, fairly obviously, just a small section of a vehicle wiring loom, the several twisted pairs of wires that I hope you can see further indicating that it is from a modern car with a sophisticated CANBUS-BASED electrical system. Look more closely still and you will spot, I hope, that a number of the conventional cables have on them the short lengths of subsequently fitted heat- shrink tubing that usually suggest, well, who knows what horrors beneath.
Let me now tell you that this morass of plastic and in some places exposed and electrically live copper wire is the group of cables passing from the cabin into the front compartment of a late-model 911, and thus – you would reasonably suppose – fairly significant to the safe and reliable operation of the car’s many systems. (Yes, I know this column has had a bit of an electrical theme this month, but I trust you will agree that it has been both informative and useful.)
And not just any late-model 911. In fact, it’s none other than a 2014 991 Turbo, even on a bad day still worth perhaps £100,000. It had been brought to Sid Malik’s Porsche-torque workshop in Uxbridge, Middlesex, with the PSM warning light on, and it hadn’t taken Sid long to find out why. At least two of the wires – to the PSM’S nearby acceleration sensor – had been transposed, despite their clear colour-coding, and once that fundamental error had been put right the warning light went out.
Even so, it took Sid many more hours of painstaking work gently to separate and minutely examine the perhaps 100 or more cables for any other damage, making good any suspect connections inside the heat-shrink tubing, and most certainly repairing the cable whose inner strands had effectively been blowing around in the breeze. Precisely why someone had been in there before him, creating such mayhem, especially in a car of this huge performance and substantial value, remains unclear, but either way the final bill – for two days’ work, some of which involved Sid laying on his back in the driver’s footwell, trying to see what was going on deep inside the fascia – was surely the bargain of the year.
991 Turbo arrived at Porsche-torque with its PSM acceleration sensor showing continuity issues, so Sid Malik started following the cables back into the car’s main loom. It was soon all too obvious that someone had been inside that before, where it passes from the corner of the front compartment back down into the cabin. Peeling away the clearly damaged outer sheathing revealed this frankly horrifying sight (top) and, teasing the individual cables apart, that many had been cut and then reconnected. At least the joints had been soldered (although that method can generate a high resistance that might cause problems in future) and covered in heat-shrink tubing, but in at least one area there were exposed live cable strands. The original PSM problem was traced to two wires being transposed, despite their clear colour-coding (solid green, and green with a blue trace). Ideally the repair would require a new grommet, too (above, far right), but since that would itself have to be cut in order to pass it round the mass of cables Sid pragmatically retained the original, making sure that it was pushed correctly into position, and thus sealing correctly. Disaster averted. But it was a close call