EWS III - No Communication Possible

[jbourne99]

Howdy,

I have a 2000 Z3 2.3 build date 10/09 that has EWS III.

I can't interrogate my EWS via INPA and ISTAP says no communication possible with that module.

The car starts fine.

The D-bus line (referred to as TXD in electrical manual) to the EWS has no continuity to pin 20 in the diagnostic connector under the hood so that seems to make sense with what I'm seeing. Since the airbag module was nearby I tested continuity from it's TXD line to pin 20 and it was good. I also tested continuity from airbag ECU TXD to EWS TXD and there was none.

General inspection of the TXD line in the vicinity of the EWS module reveals nothing and everything looks pristine.

I'm trying to find a junction box or splice panel where all these TXD lines come together but I almost have the front carpet out and can't find it. The electrical trouble shooting manual indicates there is a splice box in the passenger footwell but I nearly have the carpet out and can't find anything. Can anyone tell me where the next stop of for the TXD line in the EWS III?

Thanks for any help!

[jbourne99]

Just an update for anyone who has this kind of issue in the future.

What I've learned on internet land is that 90% of the wiring problems happen within the first few inches or last few inches of the wire. Inspecting the first few inches of the wire was easy but getting to the last few inches was difficult. The wiring diagram indicates that there is a splice in the passenger footwell where all the TXD lines meetup. I found a huge splice of 5 or so wires and had to pull the carpet to find it. It is in the front of the passenger footwell alongside the transmission tunnel. The beginning and end of the wire looked ok so I just traced the wire from the control module and unwrapped the wiring bundles as necessary to trace it. I used a continuity meter and razor to get into the wire. I eventually lost continuity and further unwrapping of the bundle in the drivers footwell toward the front and left side of the car was some green oxidation. I found the broken txt line causing the problem and a broken power line (red background with white stripe). Some other wires may have been compromised so I will repair all and re-wrap.

I'm glad I traced the wire to find the problem as it let me to other trouble that I didn't know existed. I'm not sure where that power line goes but I'll fix it anyways.

[z3forlife]

Also determine the location of the water leak that led to the corrosion.

[Randy Forbes]

Also determine the location of the water leak that led to the corrosion.

+1

Red w/white stripe is "hot in run & start" so it's a circuit that only works with the key on (there're rd/wh wires running all over the car...).

[jbourne99]

Thanks for bringing that up. 10 years ago I had an inch of water in both the passenger side and drivers side. I sealed up the a-pillars, adjusted the window to seal better along the top, and additionally make sure the vapor/water barrier in the door was sealed up (the dealer had previously been inside the door to fix something and left a gaping hole in that!). Since then it has been dry but your thoughts made me think that could have been when the damage happened.

At the same time though, I'd think that an intact wire should be water proof. Perhaps there was some slight damage to it from the factory that with the water caused trouble??

[z3forlife]

It’s water resistant not water tight. In standing water it will soak through pretty quickly. Add voltage to the mix and you get almost instant green goo where the once was a wire. Electrolysis happens very quickly. Clean the area with a baking soda water solution to kill any corrosion

[jbourne99]

Update for anyone following. Repairs made, communication with the module now possible!