Is my BCM faulty? - VW 2.0 TDI Touran 2011

[Crasher]

SC12 together with SC10, 12, 14 and 16 are powered from via the J329 terminal 15 relay from SB7 and also supplying the J906 starter relay 1 into the J907 starter relay 2, a bit of a mind bending system

[suityou01]

SB or SC 12?

Don't have my trusty Haynes comic with me today, but from yesterday I deduced :

Terminal 30 is fed from a relay, R4 on the diagram 12.29.

This is labelled "Ignition main circuits relay 1" on the web site I linked to. This relay sends power to fuse 12, Diesel Direct Injection System Control unit. With the key turned, check for voltage across fuse 12. No voltage, replace the relay.

At some point yesterday I twigged this was a 2011 model (possibly a 2010 build, therein lies the rub) so I may have been reading from the wrong diagram. The point is, to find the correct fuse downstream of the T30 relay and check for voltage across it.

Maybe Crasher if you have a Haynes to hand you could check the fuse number?

[Crasher]

Maybe Crasher if you have a Haynes to hand you could check the fuse number?

I have ELSA WIN, the car was built 30-03-2011, most aspects of the electrics changed significantly from 05-2010 build.

[suityou01]

I have ELSA WIN, the car was built 30-03-2011, most aspects of the electrics changed significantly from 05-2010 build.

Cool, do you know which fuse is fed by the T30 Relay?

[CedricTheBull]

Hi Both,

Again, thanks for all the info, I'm going to have another go tomorrow. So, I guess I'll try and check fuse F12 unless I find anything different in my Haynes manual this evening. I'm also going to pull the fuse box out and probably the battery tray AND charge the battery as it seems I've zapped it with the testing so far!

[Crasher]

Cool, do you know which fuse is fed by the T30 Relay?

Not now, home and on the iPad......

[CedricTheBull]

Hi Again,

Ok, progress so far today:

1. No, I couldn't find which fuse is fed by the T30 relay
2. Replaced car battery with freshly charged one, car cranks faster but still the same. Stupidly didn't run another diagnostic before ....
3. Took out fuse box to check connector underneath. Connector looks fine but we then brought the fuse box inside to have a good look,
we found a lot of corrosion on the strip fuses and parts of the fuse box itself, see below:

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What do you think, could this be causing the problems I'm seeing? In the process of cleaning everything now.

Thanks, Cedric

[suityou01]

Egads what a mess. I think a thorough clean with an Emery board on those terminals will at least rule out systemic failure of the supply. The only thing that springs to mind is cheap materials that corrode easily.

There should be an earth strap under the starter motor which it's worth checking with a meter. This is the main earth strap.

No matter how corroded stuff looks, it could still be making good connections. The only way to know for sure is again with a meter.

I bought a Sealey PPX probe, which makes spotting bad earths, blown fuses and voltage present an absolute doddle. Not to pricey either, and with a feature ridden car such as yours, a valuable item to have in the tool box.

The fuse you are looking for is the one that drives the diesel injectors. Check the fuse box lid.

[CedricTheBull]

Hi, been using lemon juice and bicarb and everything coming up a treat! With regards to the meter testing, I forgot to say that I did and they tested really badly! I'm using a Fluke multimeter, seems to work pretty well.

I was going to ask about earth points and where the main ones are, thanks for the pointer on the starter motor, will take a look.

Will see if I can find the fuse again, just still confused about multi system failure, still suspicious of the BCM as it controls so much!

Will keep you posted.

[suityou01]

Well the approach to cleaning is highly intelligent. At least once the fuse box is fitted and testing perfectly, you can test the rest of the car knowing that. Kind of a ground up approach that is methodical and works well with these kind of problems.

And who knows, maybe this fixes some or all things!