The female connector of your Zumo does not like salt!

Doing a simple Google search, I realise that many Zumo motorcycle users know this message as well as I now do:

>>> USB connected to wrong port

and we may all react the same way: WTF, the USB port is not connected at all, never was and never will be. No clear explanation is given when reading through all posts and comments, except for 1 recurring similarity: its wet outside, and the problem often disappeared once the sun started shining.

Here in England waiting for the sun to dry things out can be very time consuming, it may actually not happen at all for years in a row. So after some wet weekend rides in January I started to search for the places that can get wet, and to no surprise, thats nearly everywhere, but only few are somewhat related to the USB port of the ZUMO: a) the cradle unit and b) the female Micro USB connector at he end of the cable, the one you hide unter you seat, or better say: under your very wet seat.


I am not convinced its the cradle unit, as the electrics are well sealed off by a blue plastic (1) from any moving part, the only way for moisture entering the unit is through the cable connection (2). Possible, but not likely, but keep it dry and greased.

Much more likely is a short circuit or a creeping current between terminals in the female Micro USB connector you leave under your seat. This one can be exposed to a waterfall of water, and what is worse: salty water. This formula is worth remembering:

TDS (ppm) = 0.64 X EC (μS/cm) = 640 X EC (dS/m).

EC stands for Electrical Conductivity, and TDS stands for Total Dissolved Solids. The 640 seems to be a important factor, but I have no idea why. Maybe some reader can enlighten me, or not.


If you paid attention in school, you may remember that distilled water does not contain dissolved salts and, as a result, it does not conduct electricity and has an EC of zero. In other words: put your female Zumo 660 USB connector in distilled water, and all works fine. So in summer, it may rain as much as it wants, but as this water has a very low salt concentration, your ZUMO works fine on the way to Rome or Morocco.

In winter however, local councils enjoy throwing salt on the roads, so much that your bike looks like sugar coated after each ride, but its not sugar, its salt. Add water from the skies, and you have a very conductive salty mixture that short circuits your ZUMO 660, and all your GPS is willing to repeat over and over again is:

>>> USB connected to wrong port

… while it should be saying:

>> Dear user, the salt concentration of the water you dip my female USB connector in is way to high for comfort, and as you seem to enjoy doing this, I will now spam you with repeated error messages making no sense. See you again in summer.

Some more life saving informations on the subject of EC: interestingly, if the water contains very large amounts of salt, then the water becomes such an efficient conductor of electricity that an electrical current may essentially ignore a human body in the water and stick to the better pathway to conduct itself—the masses of salt in the water. That is why the danger of electrocution in sea water is less than it would be in your bath water – if you did not add too much salt.


Whatever, but did we learn something? Yes I hope, if you still want to ride in winter on wet salty roads, keep your female connector as dry as possible, Micro USB that is.


I tried to solve the problem with as small bag of silica gel (3) you find them as addition in the packaging of some food product or sensible electrical equipment, and uncooked rice, as both absorb humidity very well.


Wrap them with the cleaned and dried out USB connector in a plastic bag, and hope for the best.


Have a safe ride in all seasons!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: