Short / Overload issue

Hi all, I need some wisdom from the experts. I have a 1993 Ski Nautique with quite a few additions on the dashboard: GPS Speedometer, Perfect Pass, and a Depth Gauge in place of the clock. When I turn on the power to the dashboard everything works fine, but I recently discovered that when I engage the horn, the horn works but everything in the dashboard blanks out. The GPS and Perfect Pass all go dark and the depth finder resets.

I'd like to get out my trusty multi-meter and see what is wrong but I have no idea where to start testing. Here are my going in theories:

1. It is the grounding issue that plagues 1993 boats. If I were to go spend a day grounding everything well the problem would go away.
2. Perfect Pass, and GPS speedometers were not a thing in 1993 and I am overloading the system. I doubt this because I never pop a circuit breaker, but putting it out there as a possibility. I could rig the PP and GPS unit to run off a different circuit as I have plenty of extra blank accessory circuits. It could be that the horn always blanked out the gauges, but since they are essentially all analog it didn't matter. Alternately - I could rig the horn to a separate circuit too (and just remember to always have that circuit "on").
3. There is something wrong with my horn or the horn button.

What do you think? What can I do to correctly diagnose the problem?

Kevin

Those year boats had a ground issue. We would put a ground block under the dash and wire the gauges to it and then run a 10/12 gauge wire to ground on the battery.

When you say you have "plenty of extra circuits" do you mean the unused accessory switches on the dash?

I believe those are kind of using the same power source as everything else, so it may not fix your problem.

You may wish to use M3Fan's relay method. He used it for his Perfect Pass, but you could do it for the horn. Then just have your horn switch energize the relay >> which will then be getting it's power direct from the battery.

http://www.correctcraftfan.com/forum/forum_posts.asp?TID=21539&title=gave-pp-its-own-relay-and-power

So, here's an update. If you follow my posts closely, you'll remember that I was having an issue where my boat would crank and crank and I could not stop it. Well, out at the lake this last weekend that happened again. GAH!!!! So I started to put a few things together.

When I say I was at the lake, I was 5 hours from my house. I had no diagnostic tools, no multimeter, I just needed the boat to work.

So I pulled the dash and looked at things and thought - I had added a lot of high-draw stuff to that dash. Through-hull depth finder, Perfect Pass, and a GPS speedo. I needed the PP to work, so I cut out the depth finder (I never got it to work anyhow) and the GPS speedometer. I turn everything on and hit the horn - nothing blanks out! Progress! Then I turn the key and fire the engine. The beast roars to life and I turn the key off - and the engine turns off.

Ta-da! I've completely overloaded my poor 1993 dashboard. Time for a new approach to my dashboard! Keep it original...

Gary,
A upgrade of both the + and - wiring to the dash is needed especially if you are considering installing the PP.

91NaughtyQ wrote: 8122pbrainard wrote: Gary, A upgrade of both the + and - wiring to the dash is needed especially if you are considering installing the PP. When you say + and - wiring are you talking about all the wiring on the dash? Thanks, Gary

91NaughtyQ wrote: [QUOTE=8122pbrainard] Gary, A upgrade of both the + and - wiring to the dash is needed especially if you are considering installing the PP.

"wiring TO the dash"
What you are seeing is a voltage drop due to inadequate wire size. Very typical for the original wiring.

I have not completed my grounding block update yet. I have started to ponder a complete upgrade/rewire of the dash this winter. I'm sure my wife would love to see that rats nest sitting on her kitchen table. It would be really cool to put on better/newer/higher gauge wires on everything with no splices, do the grounding the right way, and put it all back together essentially all new underneath... maybe...

Going to do the relay switch for the Perfect Pass this weekend.