new 396 power cable arrived

[twowheelstom]

my new 396 power cable arrived today, and I just soldered 2 bullet plugs onto the wire ends and put on heat shrink tubes, I plan the bullet plugs for the accessory leads under the motorcycle seat. Next is to install the new cable onto the cradle, I hope the soldering didn't do any damage to the power cable black converter/fuse box. and I found out that I can use a 2 amp fuse on the power cable for testing to see if all works ok, I have a 12v lawnmower battery on the bench for the test

[twowheelstom]

I got the new power cable attached to the cradle, next is to install the Zumo and connect cable wires to a test 12v battery and pray the Zumo turns on when it gets volts, oh and I am going to use a 2 amp fuse

[twowheelstom]

still no luck
the 396 unit will still not power on when its in the cradle, even with a new cable

so my question now is,
when you connect your zumo cable wires to a sitting 12v battery, does your unit power on?
mine is not powering on, but will power on when I press the unit power button

any ideas?

[lkraus]

Do you have a voltmeter to verify the polarity of your 12V wiring and to detect the presence of about 5V at the cradle pins?

[twowheelstom]

if i remove the 396 from its cradle, and with power cable connected to sitting 12v battery on the work bench, can i use a multi-meter probes directly to the cradle pins?

[twowheelstom]

it blew a 2 amp fuse at the Pos red side of 12v battery.
Zumo unit out of cradle for this test

I set the multi-meter dial to Ohms
put black meter probe on black power cable end
put other probe on top pin on the cradle,
and got an Ohms reading of .000
so I assumed that top cradle pin is Neg (-)

I have a 2 amp fuse on the Pos. red side at 12v battery clamp

I set multi-meter to Volts reading
checked volts on battery clamps, its 12.7v

put red battery clamp on power cable red end
put black battery clamp on power cable end
put Neg. black probe on top pin on cradle
and then put Pos. red probe on bottle cradle pin
it blew the 2 amp fuse at the red battery clamp

I wonder if the pins are reversed, maybe the bottom cradle pin is the Neg (-)
how can i tell which pin is which?

[twowheelstom]

new test to see if the 396 unit will power on when connected to the 12v battery on the bench
this time using a USB car charger

USB car charger plugged into the 396 unit USB port, then connect to 12v battery
works, the 396 unit powers on
so this proves that the zumo unit will power on from the car battery

the problem is probably with the cradle power cable -or- the problem is the cable power pins
I am suspicious that when the 396 unit is snapped into the cradle, the power pins are not coming into contact with the back of the 396 unit

[twowheelstom]

Do you have a voltmeter to verify the polarity of your 12V wiring and to detect the presence of about 5V at the cradle pins?

test included a 12v car battery on test bench, a multi-meter, and old and new power cables, both are the same part number.
I had bought the new 396 power cable which I installed in the cradle,
and with the zumo in cradle with the new cable there's no power to unit and no volts reading between the cradle pins
multi-meter shows an ohms reading on the (-) pin and nothing on the (+) pin and with test battery there's no volts reading betweent the 2 pins
so I put that new cable and cradle aside for a new test on the older cable in no cradle

with the older power cable, I cut it (in-between the cradle pins side and the converter box),
leaving off the converter box for the following test
I found that the old cable negative (-) is bare stranded wire that wraps around a white wire that's the positive (+).
So then with 12v test battery with battery clamps and a 3 amp fuse on the older cable (+) and (-)
the multi-meter probes found that the top pin at the cradle (the top pin being the one closest to the retainer screw) is the Neg (-)
and with test battery, the multi-meter probes on both bottom (+) pin and top (-) pin on the older cable measured 12.5 volts
this was all bypassing the dc-dc black converter box
on the new uncut power cable with the attached dc-dc converter box, there's no volts between the cradle pins

so either the converter box is the problem -or- the zumo unit is not in full contact with the pins

[twowheelstom]

this test is on the cut-off part of the older cable with its converter box attached
the multi-meter shows an ohms reading on Neg (-) wire on the either side of the converter box
but when applying 12.4v test battery clamps to the (+) and (-) wires, the cradle side wires shows no volts reading
I don't know what triggers that converter box to allow current to flow thru it

[lkraus]

My XT uses a similar (same?) converter box to supply 5V to the mount. I think early 39x and XT models had a 2A fuse and holder on the 12V input. Later models like my 2021 XT have electronic circuit protection built in, so no fuse is needed. In the event of a short circuit or 12V input polarity reversal, it just shuts down. It is reset by switching off the ignition or otherwise disconnecting the 12V supply.

The top pin on the XT mount (nearest the release mechanism) is +5V. By probing the coaxial cable between converter and mount with a thin needle, I've confirmed that the braided outer wire is negative and connected to the bottom pin.

I've never seen a 396, but I would be very surprised if Garmin used a different method to power the 396.