Weird start/non-start problem - help needed

[HPsauce]

Originally Posted by spannerrash

I didn't even realise there was that 3rd row under the noise insulation.

I had a vague idea there was something there, but not quite sure what:

Originally Posted by HPsauce

I can't recall the layout there, is that the main panel under the "board" under the passengers feet, or the section that I think is above it?

But the lack of a row of fuses (as on the diagram) on the obvious 2 rows made me look higher up and there they were.

All covered by the "board", or in my case a lovely piece of thick black plastic material manufactured by Sean.

[spannerrash]

I have this (picture below), PM me if you need it at all. I'll send it to you.

You could use it as a template for making up your bridge wire if you decide to go down that route.

If you don't use it in the end, just send it back.

[HPsauce]

Originally Posted by spannerrash

I have this (picture below), PM me if you need it at all. I'll send it to you.

Many thanks, I'll probably take (and keep) that for backup/testing; PM coming your way.
How come you have that kicking around?

I've already made up a wire, using 6.3mm tags as MJ suggested. I'll try it another day though, once I've worked out EXACTLY which holes to bridge - don't want to blow a fuse somewhere!

[spannerrash]

I have a real paranoia about needing something to keep my car running that becomes NLA. Thus I spend a fortune on buying random bits just incase I need them. This was bought, along with the other footwell relays from a8parts.

I'll send it out tomorrow morning.

[steamship]

This is just a FYI, following Andrew identifying the relay, part number 431951253H.

Searching ETKA for that part number shows it was used in the A8 up until 1999, and is listed as being used 'for vehicles with auxiliary heater'. It then shows that it was superseded in 1997 with part number 141951253B, in 2005 with 8D0951253A, in 2007 with 8K0951253, and finally in 2010 with 4H0951253A.

Searching for 141951253B instead against Andrew's car reveals two instances of it, in positions 1 and 2. Position 1 just lists location and code (204), with an 'automatic' comment against model. Position 2 lists 'relay switch for seat adjustment' (which doesn't seem present in Andrew's photo - odd!). The two green items are 30A thermal fuses, and the two 373 relays Andrew refers to are for 'day driving headlights and 1st stage radiator fan' in position 4, and '2nd stage radiator fan, fuel pump and fuel cooling' in position 5. You'll have noticed that there is no position 6 as shown in the wiring diagram illustration I uploaded previously, as in ETKA the two thermal fuses are both allocated position 3, with the relays being 4 and 5.

If that isn't confusing enough, ETKA also lists part number 8D0951253A for Andrew's car, despite that part not becoming available until 2005. So, although we have two 'official' sources of information for all this, there is still inconsistencies.

[HPsauce]

I'd already come to the conclusion that the various technical sources were a combination of vague, confusing, inconsistent and just plain wrong!
Which is why I decided on extreme caution, took it apart, looked and took photos.

[HPsauce]

Originally Posted by HPsauce

I've already made up a wire, using 6.3mm tags as MJ suggested. I'll try it another day though, once I've worked out EXACTLY which holes to bridge - don't want to blow a fuse somewhere!

I'm also thinking ahead and wondering whether to extend any bypass wire to a switch somewhere that I have to push/toggle to close. This would mean starting would require both the normal key operation and operating a less-than-obvious switch. Safety feature and security too.
No blank/unused switches on my car though, even the blank space to the right of the steering column has a switch now, for video-in-motion.

[moltuae]

Originally Posted by HPsauce

I'm also thinking ahead and wondering whether to extend any bypass wire to a switch somewhere that I have to push/toggle to close. This would mean starting would require both the normal key operation and operating a less-than-obvious switch. Safety feature and security too.

Originally Posted by HPsauce

No blank/unused switches on my car though, even the blank space to the right of the steering column has a switch now, for video-in-motion.

You need to think like 'Q':
https://i.imgur.com/oJV8rhF.jpg

Or, plenty of room under the armrest:
https://i.imgur.com/ZSjGycc.jpg

[HPsauce]

Originally Posted by moltuae

You need to think like 'Q':

The gear shift button would be a subtle one to use, I think it just operates a mechanical interlock.
However I think it would be quite difficult to engineer and make reliable as the wires would flex regularly.

[HPsauce]

Originally Posted by HPsauce

I found another problem when gaining access, water under the carpets...
The scuttle is actually dry so this must be the aircon drains again.

Or maybe not on consideration. Whenever my aircon drains have blocked I get the water dumping noisily out of the tray on cornering. Ever since I trimmed the orange drain tube tips that's not happened.

BUT I did find the scuttle full a few weeks ago, so I reckon it's probably overflow from that and has just stayed there since. The fact that it's almost all just on the nearside supports that, I think the overflow from the scuttle always comes through there. Aircon drains overflow both sides.
Anyway, fingers crossed, but I'll take out the (easier) passenger side trim soon and check/clean before I finish this job.