An interesting defect on my Touran

Had an interesting defect and I've shared with some friends over a chatgroups, One of them told me is "blog-worthy" and asked me to update my blog. ok....

The situation started with my dad calling me saying that my Touran had a defect (what's new right...). I thought it was some usual issues like those that I have previously written about. I, Me, Myself, Ivan: Defects and Symptoms encountered - Volkswagen Jetta and Touran (ironman76.blogspot.com)

Turn out, the car, once engine off, the power supply was totally cut off, as shown in the picture below.

What is your first thought? Battery I suppose... but for me, I don't think its battery issue. 

I'm using a Tsapa Battery(120X). I overheard some issues experience with Tsapa battery (not 120H or 120X), so I thought maybe 120X also got problem. So first check the battery.

Result, a super healthy battery with 13.3V. So what's next. probably fuse.... checked all, all not blown. 

Then try to use multimeter to check wiring connectivity.  

Interestingly, the voltage difference between the grounding point is >10v!!! Had previous issues on grounding cable so I actually had installed another grounding cable with a "fake HKS" grounding wire. 
And turn out that grounding cable connector was open circuited.

I had previously damaged the original grounding connector and had used a self improvised self tapping screw to hold the ground cable. turn out, the screw thread seems to have loosen over the years and probably cause the open circuit. 

As a recovery action, first need to see if the self tapping screw can still fit it properly. But it was loose. so I decided to give a better ground connection by removing some of the paint. 

Then I went over to a hardware shop to buy a bolt and nut to tighten the grounding point. and ya, i still got spare "fake HKS" grounding cable. 

Once all is connection, I finally got power supply back in the car

but more errors appeared. 

And worst

Almost at wits end, but decide to trigger a fault on the speedometer and thankfully it worked with all the fault codes available back on vagcom. Means got change to reset and work.

However, after a reset, I encountered a steering angle defect and couldn't clear despite resetting it.

Eventually, I tried to go into the steering wheel adaptation page and managed to resolve the defect and was welcome with a clean error free message on vagcom.

Finally my defect is rectified!

For info... The key use of the battery is just to start the car. Once started, the alternator takes over the power supply function of the car. So what is the root cause of defect.

1. Suspect the self tapping screw was the root cause. having intermittent connection all these while. 

2. The additional ground cable had an open circuit. hence there is no additional grounding point even though there is intermittent connection. 

Recovery action. 

1. Sand away the paint and also use a bolt and nut to secure the connection better with an additional grounding wire as contingency.

Total cost for me. 

I went opposite my place to buy a packet of bolt and nut for S$3.