Thread: D3 Multiple Lost Module Communications

When you say the ecu next to the battery, I assume you mean a 2nd battery fitted near the brake master cylinder as that ecu is the transfer case module. Therefore I think you are looking in the right spot, at least to start with. Check any earth posts nearby for being tight. The TC ecu is known to not like water but I don't know if that's due to connection problems or if the ecu actually gets damaged. You could try some electrical contact cleaner on the TC connector. As the fault increased in frequency rather than immediately permanent, a poor connection is more likely the cause than a failing ecu. However due to multiple lost comms, a connection fault could easily be somewhere else.

Thanks Graeme for the input.
I was meaning the ECU near the main battery that looks like a terminal block almost. It's mounted to the side of the battery tray so to speak...lots of wires in from the top and not a lot of insulation to keep moisture out. It looks fine but figured it worth checking the connections today.
I'll be looking closely at the TC ECU for sure after your suggestion.
Cheers.

On my D4 that looks to be a loom connector and as it doesn't have any light gauge and twisted pair canbus wires out the top I doubt its the source of the faults.

Hi Mully, do you have an electronic brake controler on? Mine gave me some grief breifly after the battery had been disconected.

Just a silly left field suggestion, and only as I'm sure I've read it on here somewhere before, & although I know you said your alternator output seems fine, BUT what about a dodgy battery???

As I said, I'm sure I've seen reference to all sorts of warnings, error messages etc. just due to a poor battery. Even your list above does say 11.75v as ECU supply voltage - not the best I would have thought ...

Regards,

Les.

id have to look at all the codes,, cant work off just one code, but look for battery acid leaking on to the TCCM, very commen,

seen a few were the harniss as actuly been eaten away,

Originally Posted by outasight

Even your list above does say 11.75v as ECU supply voltage

I missed that!

Hey guys thanks a bunch for all the messages, very appreciated.

I've just got back inside from fixing a loom chewed by rodents! When removing the battery (I have a massive BMW AGM battery nowadays that is brilliant) to check the ECU located behind it, there is a loom connector at the bottom rear that had a load of chewed wires. One wire was even laying by itself in a one inch length completely separated from the loom... they were having a good munch it appears.

I still needed the Faultmate to clear the big F message but all the errors are gone and I'll take her for a spin tomorrow to see how she goes while hoping some other niggles are now also gone.

Will still also replace the brake switch anyway although it serviced up ok but one contact in there is certainly under rated.

What a saga... but I will definitely state for the record that the looms are very ordinary on such an electrically featured vehicle. I was stunned by all the loomed cables left dangling and exposed throughout the under bonnet areas. Not quite the standard of cabling I expected to see...even in a British build.

If anyone wants some pix of the rodent meal, let me know and I can whack some snaps up.

Thanks a heap again one and all for taking the time to give input.