Deeper dive into these fault codes

[n10n]

Today was the day to get the CCS installed so I had a good look under the battery. I changed both starter relays for known-good. I checked the wiring, the connections, nothing had corroded - all squeaky clean. Put it all back together again - cleared the codes and... still get two fault codes

Definitely no aftermarket devices or wiring under there either.

Next on the list of things to try is an ECU reset.

Just to confirm, you checked J906 pin 6 (blue/black) continuity to J623 (ECU in ebox) pin 85, J532 voltage stabilizer in ebox pin 4 and BCM white connector pin 50 (red / black at BCM)?

Or then it’s indeed haunted

 

[CJW]

Hi

I checked these:

Visually inspect the connections and check continuity to the ECU, which is pin 1 of relay 2 to the ECU, and pins 2&6 of relay 1 to the ECU

I did miss checking between e-box and BCM, apologies! Would have been tricky without help but that’s not why I didn’t check it.

 

[CJW]

One thing I couldn’t do was check voltage to the relays since the battery has to come out.

I just noticed that this coupling point behind the glovebox has a repair that’s nothing to do with me. I can see how it would be easy to break though, it catches on the glovebox.

I also noticed that a small wire with Tessa tape passed through the wrong place and was probably under pressure from the glovebox.

I wonder if the feed from the SC23 fuse passes through this coupler? I tested the fuse itself once the dash was out - continuity and no resistance.

The green connector is T17k. I’ll dive into the wiring diagrams.

 

[CJW]

Nope. Power and data for the interior alarm sensor.

 

[CJW]

Update : ECU reset made no difference.

I’m going to get a second opinion on this starter battery. Have ordered a testing device.

In the vehicle’s itemised history I can see the starter battery was changed in 2020 for the current Bosch. I asked VW to test the battery - they said status ‘green’. That was last year.

We’ll see if the testing device agrees with VW. If it does - haunted.

 

[CJW]

Device arrived today.

Interesting result:

Battery was indeed given the green light BUT the ‘Health’, which I take to mean SOH, is only 52%. I checked the itemised list of maintenance work prior to me owning it again and the battery was changed in March 2020, so 3.7(ish) years ago.

Reading about how SOH is interpreted by devices, some will fail a battery at lower than 50%.

So @mmi ’s ‘poor battery’ initial comment could still be the reason.

New battery time I think.

When I get chance, I’m going to compare the device’s readings against the similar stats that I’ve seen can be reached with VCDS.