MK7 2.4 TDCI problems again

[marcrbarker]

If looking for suggestions for more non invasive tests... Intermittent and random faults are a right royal PITA and cleaning things and hope for a break doesn't cut it in practice.
But there are tricks to find intermittents. One way is set up some continual test going provoke them out while watching, wobble things around bang them etc. With PCBs while listening to a test audio tone from the circuit you'd stir components around with a paint brush and spray freezer spray, ....you get the idea.
Another way is set a trap that catches the fault in the act, takes a snapshot. Fancy equipment.
So next best thing with scantool set up a livedata capture running continual data try include the modules that report DTCs comm failures. While running you can waggle things round till something happens.
I would be suprised if you didn't already waggle harnesses around while engine running to provoke a stop. Something I've learned about intermittents is if you don't find something concrete that caused it then the fault will always return!.

[naumanijaz116]

From what you've described, it sounds like the issue is more likely related to the **ignition switch or an electrical feed** than the wiper stalk itself.

The fact that unplugging the wiper switch temporarily changes the behaviour suggests you've probably been disturbing the wiring or connector around the steering column rather than fixing the actual fault. I'd start by checking the ignition switch on the back of the barrel and its connector. Try gently wiggling the key while turning it to the start position—if it behaves differently, that's a strong clue the ignition switch is failing.

The symptoms also point towards a possible **electrical backfeed ("sneak path")** between circuits. A damaged switch, broken spring clip inside the stalk assembly, damaged wiring, or even a previous fuse repair can allow power to feed into circuits that should be off. That could explain why the engine won't switch off, why the dashboard lights up unexpectedly, and why the batteries appear to drain intermittently.

The dashboard showing lines and all warning lights illuminated also suggests the system voltage may be dropping too low. Although the AA said the batteries tested OK, if they were previously **completely flat**, they may have suffered permanent capacity loss. A battery can still show the correct voltage after charging but have very little reserve capacity, so even a small parasitic drain while you're in B&Q could leave it unable to crank the engine 30–40 minutes later.

If it were mine, I'd check things in this order:

1. Ignition switch and its connector.
2. Steering column wiring and the wiper stalk for damaged insulation or internal shorts.
3. Measure the parasitic current draw with the vehicle locked.
4. Load-test the batteries rather than relying on a simple voltage test.

Given the combination of random electrical behaviour, battery drain, and the engine not switching off, I'd be looking for an **electrical backfeed or failing ignition switch** before replacing any more parts.