New GPS/Chartplotter install, keeps blowing fuses

[devildg4671]

I just removed an old Garmin GPS/Depthfinder on my new boat and replaced it with a new Lowrance HDS-7 Insight USA. I hooked everything into the same places the garmin was, but soon as I hit the battery switch it blew the main fuse near the battries which happens to be a 20a fuse.
There's only two things that are wired into the switches on the control. They are a Vhf and the HDS-7. I unhooked the Vhf and the everything worked fine, I also did the same for unhooking the HDS-7 and the Vhf worked. I thought maybe it was due to the fact there's 3 black wires tied into the 12v power outlet, both the Vhf and the HDS-7 are 2 of those 3 wires.
I even replaced the fuse with a 25a fuse. No luck.

So, did I do something wrong or should I try using a larger amp fuse ?

Any suggestions will be greatly appreciated.

 

[wifisher]

Re: New GPS/Chartplotter install, keeps blowing fuses

DO NOT use a bigger fuse. That could be a good way to start a fire if the wires can't handle it. Be sure the polarity is not reversed where you hooked up the new GPS. Try unhooking it and turn power on with those wires unattached (make sure they don't touch metal). If the fuse does not blow it is definitely a problem with the new GPS or the wires running to it. Could also put an ohm meter on the wires to check for a dead short.

 

[NYBo]

Re: New GPS/Chartplotter install, keeps blowing fuses

Don't install a larger fuse! The wiring may become the the weakest link and start a fire.

The HDS-7 only draws 0.8 amp with the backlight on, 0.4 with it off. Therefore i think something is wrong with the wiring. Can you post a diagram or picture of it?

 

[devildg4671]

Re: New GPS/Chartplotter install, keeps blowing fuses

I hooked the same wires to that the garmin were connected too. I also, disconnected each one and they worked fine. It's just when they both are together. I've attached a photo, I hope this helps and everyone can understand.

 

[Fireman431]

Re: New GPS/Chartplotter install, keeps blowing fuses

If you are blowing fuses, you obviously have a dead short. Somewhere the power and ground are interfering. You wrote that there are 3 black wires tied into the 12v power outlet. It appears that one of these is a ground. Use a test light and find out which one it is.

I'm sure that the Garmin is just fine, as they are bench tested prior to leaving the factory and it works when not hooked to the VHF.

Why not just wire them independently like they're supposed to be? If you don't go reusing wires from other units and install new, guaranteed no issues.

 

[devildg4671]

Re: New GPS/Chartplotter install, keeps blowing fuses

The 3 black wires are connected to the 12v connector that has a jumper wire, that attaches to to each one of the switches top connector. As ya'll can tell I'm very new to this although I do have some basic wiring knowledge. I took the old wires off the garmin and I did not re-use them, I just wired the new one straight to the same switch connectors.

Could someone please explain how to wire them separately,

 

[Silvertip]

Re: New GPS/Chartplotter install, keeps blowing fuses

The black wires on the switches that jumper from one to the next should not be used as ground for other accessories. Those wires are the grounds ONLY for the internal light on the switches. The boat has a ground bus somewhere. Ground the accessories there. See all those orange wires going INTO each circuit breaker (labeled 10A)???? That's +12 volts. Pick off +12 volts there or follow them back to the source.

 

[NYBo]

Re: New GPS/Chartplotter install, keeps blowing fuses

Other than tapping the negative at the end of the line, so to speak, your wiring looks perfectly fine, so I'm confused as to why the main fuse is blowing. How are you disconnecting the two devices for your tests, just turning off their respective switches? What other loads are on when the fuse blows?

 

[NYBo]

Re: New GPS/Chartplotter install, keeps blowing fuses

The black wires on the switches that jumper from one to the next should not be used as ground for other accessories. Those wires are the grounds ONLY for the internal light on the switches. The boat has a ground bus somewhere. Ground the accessories there.

I agree, although I'm not seeing why the current setup is blowing the main fuse.

 

[devildg4671]

Re: New GPS/Chartplotter install, keeps blowing fuses

I've disconnected each item from the switches. Which just left one connected at a tome and everything worked fine. But soon as I connected the black wire on the left, it blows the main fuse. So it seems there's a problem with those 3 black wires.
Also, when I'm testing these, there's nothing on not even the equipment or switches.

 

[Fireman431]

Re: New GPS/Chartplotter install, keeps blowing fuses

On the left, what is the red/black wiring for the HDS-7 run together?

 

[Fireman431]

Re: New GPS/Chartplotter install, keeps blowing fuses

Could someone please explain how to wire them separately,

Both units should have independent wiring schematics (obviously). Run the 12v (red) wires from each unit to their own 12v(+) power supply, using a 5 amp fuse, either in-line or connected to a buss bar.

Run each units 12v (-) black grounding wire to a known grounded source or to a negative grounding buss bar. Tapping off of switches for power is acceptable, but I always run independent leads so I know later which run goes to which unit.

 

[devildg4671]

Re: New GPS/Chartplotter install, keeps blowing fuses

The red/black wore on the left is a wire thats ran from the vhf. That's also a wire that I did not move and it was already connected.

 

[wifisher]

Re: New GPS/Chartplotter install, keeps blowing fuses

From what you are describing, it sounds like you may have a short in the 12v power outlet. Try disconnecting the 3 black wires from there and test that terminal for voltage. If there is voltage present at that terminal it is the cause of your problems. I have seen this several times caused by a penny accidentally dropped into the power outlet. If there is no voltage present at the terminal, then check each of the wires that are connected there. If any of them are showing voltage then it is causing the short.