Why does this wire kill my electrics?

SimonAW

SimonAW

Member
 Dorset
I've been fault finding my Z4 for a few days, it has had intermitted electrical faults which like so many others on the forum, I tracked to the airbag module between the seats. I fixed a broken connector pin on it and my electrics are now solid as a rock, sorted.

One thing was annoying me that the radio says "disabled", not a big deal but I wanted to see if I could check all the other cabling in the car to see if anything obvious could be causing it. I have checked all the other airbag modules and they are all clean with no water damage, but I did find this cable block which is located behind the passenger side rear storage hole. It has what looks like a data wire disconnected, so I plugged it back in, reconnected the battery and random electrical issues occured, no windows, no roof, lights on the dash cluster not appearing, airbag light on...and probably other stuff i missed. I pulled the wire back out of the block and the car is back to normal again..all good.

So can the hive mind of the forum tell me what the wire is for and why you think it might be affecting the electrics like it is? One thing to note is that I have the factory ipod module fitted and the fuse for the cd changer is removed, not sure if that makes any difference, the rest of the car is stock.

First picture shows the location of the block.

Second Picture is the wire in question

Third picture is the hole it should be in?

Fourth picture is the opposite side of the block.
 

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How certain are you it goes there, it looks like there's 2 possible wires on bottom row of connector or the other one on top row, next time mines out I'll pull storage bin and have look
 
its worth a look on the wiring diagram- but it looks like it should go in that hole to meet the same coloured wire the other side of the plug-

Still worth a check though
 
I'll stand corrected but I think that plug is the power to the hood assembly?
 
bigwinn said:
its worth a look on the wiring diagram- but it looks like it should go in that hole to meet the same coloured wire the other side of the plug-

Still worth a check though
Click to expand...

Have you not got one outside in many pieces to take a look at :rofl:
 
The smart top module for e85 plugs in somewhere around there. And yes there is a smart top for e85 before anybody just down my throat
 
markplant said:
bigwinn said:
its worth a look on the wiring diagram- but it looks like it should go in that hole to meet the same coloured wire the other side of the plug-

Still worth a check though
Click to expand...

Have you not got one outside in many pieces to take a look at :rofl:
Click to expand...

too many Mark!!!
 
Thanks for the replies so far. I presume it goes in that hole as it was kind if half in half out when i first found it and presumed it was just not fitted correctly, but i wonder if someone had pulled it out on purpose at some point?

I wonder if the next port of call is to check the x10116 which i think is behind the dash near the fuse box?
 
That's a kbus wire so if it's in the wrong place, only partial connection or the module it's attached to is faulty that will explain all the electrical problems. Hence my guess about the dodgy module pin earlier.
 
If I leave the wire unplugged, as I found it, everything in the car works as it should as far as I can tell.

If I plug it in, my OBD reader cannot communicate with any of the airbag modules, the roof and windows don't work, the dash lights are all random, airbag light is on and probably some other i missed.

Obviously I can leave it unplugged and the car is working fine, but it will niggle at me untill i know what it is meant to be connected to. The Radio still says "disabled" but I am unsure if they are related as I think the radio issue is related to the ibus (white/grey/yellow), but I am no expert so happy to be corrected.
 
Basically one of the modules on the kbus is scrambling the data. To identify them you're probably reduced to unplugging them one by one and see when it settles down, or use INPA etc to see which one won't talk.

The radio is part of the same problem. It talks to other modules in the car to decide if it should work or not, rather than having a code.
 
So, I just thought I would add an ending to this thread. Two years later...

I never did anything regarding the data wire that was pulled out of this plug. It only seemed to affect the stereo having "disabled" stuck on for a while, which then randomly cleared one day, the steering wheel controls did not work, and the clock would not appear on the radio.

But the other day I just got in the mood again to fix it, so this was my thinking..

The plug in question is behind the passanger seat, near the roof module, so I thought maybe the roof module was faulty or had corroded pins similar to what I had to repair on my other module between the two seats on the floor. So I got the roof module out and removed the outer casing. Using a multi meter, i traced the data wire from the plug to the pin inside the roof module and there was a beep so I knew now they were connected. However, when I touch the probe to any metal part of the roof module circuit board the multi meter beeped, showing that the data wire was shorted to ground. So I took photos and then disassembled the plug, everything looks fine if a little dirty. A bit of cleaning with contact cleaner and reassembly and another check then showed the short was gone. I connected everthing back together and bingo, rado working, steering wheel controls working and clock showing on radio.

So yeah..short to ground...and it only took me two years to muster up the energy to go do it, then 30 mins to fix. We will see if it stays fixed, but so far so good.
 
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