as was my job in fixing issues with newly produced cars
the odd one would produce bad behaviour that would baffle, perplex and mystify the rectification electricians and the call would come for someone from Engineering to come down and sort out the problem for which the sparky was not getting adequately paid for all that shit.

Cue one whose automatic gearbox would fail to calibrate and clear diagnostic fault codes which prevented the vehicle being moved on and sold and the guys had tried everything- new gearbox, new control unit, new wiring loom, new reprogramming of the module- all failed. No shorts on the wiring, no open circuits, no nothing. Days went by and the production supervisor got very shirty with us for not fixing this car that a customer had paid for and was expecting to be delivered to his dealership.

Then after exhausting all possibilities the maufacturing engineering guy went to get in and select neutral to move the car, putting the hazard flashers on as standard procedure and with his foot on the brake with the ignition in.

Now as anyone who has driven along behind a dodgy old Ford Sierra will recognise, sometimes you get this effect where the indicators blink on and the brake/tail lights go dim at the same time time. Well, there's a good reason for that and it's to do with bad (corroded) earthing. This brand new car was doing that very same thing and so we went back to the wiring diagrams.

Then within 5 minutes we pulled back the trim and found an earth eyelet not connected- the same earth eyelet which should have been bolted down to an earth stud providing an electrical circuit return to four or five separate ground wires, one of which was the transmission control module and the others were the rear right lamp cluster.

Turns out that with the key on the transmission module was only operating because, with no earth path the electrical feed was now earthing backwards through the brake lamp bulb into its control module input, so every time you put your foot on the brake the transmission module had no grounding and turned off. No short, no open circuit to earth (although not a very good one) and £1000s of pounds of labour and parts later... finally fucking cracked it! Now to find out how they fucked up the DC Tooling which is supposed to ensure that these kinds of mistakes can never EVER happen- so they say.
( Rotating Wobbly Hat That's not a banana. THIS is a banana., Sun 16 Oct 2011, 20:22, 2 replies)

*gets a little nerd stiffy*

(Schindler's Wrist Brimful of asha and a P45, Mon 17 Oct 2011, 10:01, closed)

Bad earth?
Fucking noobs. Should have been the first thing checked once the initial conclusion of "these results makes no sense" was arrived at.

And no poor customer to bill for it? LOL
(CADmonkey rollllllllled another one, just like the other one, Mon 17 Oct 2011, 10:07, closed)