Yes, a diode would help with the negative voltage. Just put it inline with the silver band toward the monitor. That would be the easiest to try.
It will also drop the voltage a bit, so if the monitor is picking up a low signal (0.5V or less) frome the brakes that can filter it out. More in series can drop it more.
The flickering is probably due to induction from the brake/reverse wires close together on a long run giving it similar characteristics of a transformer, just all pulled out straight. Transformers need AC to to work, but with DC it's 1 cycle so 1 little pulse.
If a diode doesn't do it, then a relay will but then you get click noises when reversing. An optocouplers gets a little more complicated but would be nicer.
With the relay you would connect the coil to the reverse lights wire and ground - That would switch the relay on when you switch to reverse, but there won't be enough power to pull it down from just the brakes. The switch side (common) can be sourced from the monitor or PC power, and N.O. connects to the monitor input.
An optocoupler is a small 4 or 6 pin DIL chip. It essentially has an LED in it that when emitting turns on a phototransistor. The LED side needs to be ~2.2v so a resistor is needed. 1.2K ohm would be fine to drop 16v to 2.2v. The other side would just be any 12v and the monitor input like the relay. It may be the same idea as the monitor has internally though, so the relay would be a better choice since it takes more current to turn it on.
Hmm, a better idea would be a resistor, say 100 ohms, and an electrolitic capacitor after it between the wire and ground. That could suck up the short pulse before it gets to the monitor. Not sure what size though.
Here's how to go about it (off memory) you can go to the My Computer icon, right click it, click "Manage".
Go to the device manager.
find the BU-353 which MAY be labelled as serial to usb or something weird (i dont know, i dont use any windows machines with my puck, i have it connected to a Linux machine in my car).
Just look around for it.
Right click it, click on properties.
click the "advanced" tab when the new window comes up, may take a second or two.
click on Advanced Port Settings
leave everything else alone EXCEPT for the COM port number. Set it to something that is not in use OR com port 1. As long as you dont have any ACTUAL serial connections connected to your computer, you should be fairly safe forcing it on com 1. Click OK out of all those windows and tell your software to always check for port 1.
Just remember to physically ALWAYS connect that USB puck to the same exact usb port on the computer, otherwise it changes port numbers. If you decide later that you need to change it, do the same thing i outlined above while plugged into that port. You can set them all to port 1 if you want, the computer will auto set to com port 1... at least it should. I'm basing this off memory since i haven't done any GPS stuff with windows in a long time.
Good luck! let us know how it goes and if this was successful for you. :)
hey thanks! that's what i've been hoping for, i'll give it a shot.
ok, i forced the gps to com1 and it seems to be a little better. most of the time after coming out of hibernation it seems to detect the gps automatically. however once in a while, I have to goto settings>navigation and then select save without even changing any options and it works immediately.
sorry, if you tried this already, i only quickly skimmed the thread, but why not give xport a shot. i've never have any problem with xport and xp setup.