View Full Version : Another Grounding question

04-12-2011, 01:15 AM
Is there any reason that one should not run a dedicated ground wire direct from the battery to the instrument cluster? I'm not sure where the instruments are getting ground from...someplace on the block I presume. (1995 PS190 350)

04-12-2011, 06:46 AM
I'd be interested to hear the verdict on this. My tach drops a bit with everything I turn on. Running just the heater makes it show 1000 rpm lower. I really want to sort this out before summer.

04-12-2011, 06:48 AM
The ground comes back from the engine in the wiring harness. I don't think that you will hurt anything to run a ground directly to a block for the instrument panel. Often times if you just trace the ground from the battery to the engine you can clean up that connection.

04-12-2011, 07:45 AM
I ran a 8 or 10 ga from the block to my ballast swtiches when I put 2 pumps in a few yrs ago. All the little crap wires up there made me nervous. Also, I ran a separate ground from battery for my little amp (2x45w) as well. All works well.

I think I see some drop with the factory items when I turn on my nav lights though, but that is not often. Now I think about it, I could swap all the ground to the big wire from the block, although that is low on the list...

04-12-2011, 10:14 AM
I ask the question because…grounding seems to be a big pain for just about everybody. In my case…voltage at the instrument cluster was reading low, about 10.8 volts. This, as indicated by the OEM volt meter, the PP, and my hand held volt meter. Adding a dedicated ground direct from the battery brought the voltage back up to 12.5v, indicating that there is a poor ground in the circuit someplace. There are a lot of wires in the cluster and in the wire harness. So I started cleaning every connection I could find. This helped a bit, but did not totally restore the voltage. So what unseen issue could be created by simply adding a ‘direct to battery’ cluster ground wire, bypassing the whole block and wiring harness. I can think of one possible problem but want to fish for other thoughts and opinions. Thanks S

04-12-2011, 10:52 AM
You can only help things by running an extra ground. Most of the time the ground wire from the battery goes directly to the block and then ground wires are taken from the block. There are usually several connectors, splices, crimps, and smaller gauge wires running all over the boat. Can't hurt.

04-12-2011, 12:51 PM
I had all kinds of electrical issues stemming from poor grounding. I always theorized that the daisy chain approach to grounding the gages behind the dash was the culprit. That, or simply having too many devices connected to an under-rated ground wire. I finally bought a terminal strip, ran all my ground wires to their own screw on the strip, then I ran a 10 guage wire from the terminal strip to the negative post on my battery. This action resolved my electrical problems. Volt meter reads higher > than 12 volts now too. Good luck.

04-12-2011, 02:31 PM
I have been having electrical issues since I added a second battery and installed a Perko switch ( the electrician changed all the connections so when the switch is set at zero not even the bilge pumps work... ) . My gauges don't start working when I switch the engine on,except the voltage and the star gazer. I live in Greece and there isn't an authorized MC dealer so I just have to deal with an electrician that hasn't dealt with MC boats before... Could someone provide an opinion regarding my problem and some pics of what the ground cable form the gauges looks like and where it should start and end so I can have a personal look and opinion?

04-12-2011, 09:43 PM
I went from picture one to picture two. Was having some really weird sounds coming from the stereo. Basically pulled everything apart and started from scratch. I installed terminal blocks for all the power and ground leads and replaced all the cables with at least two sizes larger cable where ever possible. Also replace the on/off switch with a Blue Seas ACR add a battery kit. Everything works great now.

04-13-2011, 10:10 AM
how does the acr add a battery kit work? I see the switch, and then that little box, im assuming it has terminals in there took hook up each battery?

04-14-2011, 01:05 AM
Hi Jack! How are you?

04-14-2011, 02:15 AM
A good ground is like sex . . . you can never have too much. :D

04-14-2011, 02:16 AM
A good ground is like sex . . . you can never have too much. :D

04-14-2011, 01:01 PM
I had a similar issue with my boat - the voltage gauge on the dash read about 11 volts, I could change the fuel gauge by 1/4 tank by flipping on the blower, my tach would go crazy randomly, etc. I was planning on upgrading the ground to resolve the issue.

But, I pulled the dash, unbolted every wire connection at every gauge, cleaned with DeOxit (http://store.caig.com/s.nl/it.I/id.64/.f) (also available at Radio Shack), and put everything back together. I pulled apart all the connectors (at the engine, under the dash, etc) and used DeOxit on those also.

Now, my voltmeter reads about 14.4V, my fuel level stays constant no matter what I turn on. and the tach is solid.

I'm not saying that pulling a new ground won't fix your problems; just giving a bit of insight into my approach. Pulling a new ground is easier.


04-14-2011, 01:13 PM
Bad grounds can do the strangest things. I had similar problems when I got my '77. Only the tach and blower worked. All the rest of the gauges, bilge pump and running lights did not work, or only occasionally at best. All working fine now.

04-14-2011, 01:25 PM
If you spent the time cleaning everything up, it would be wise to add a little di-Electric grease to the ground connections. It will help protect the connections from corrosion.

...If you boat in Saltwater, you have to be especially dilligent with grounds. A bad ground could allow electrolosis to enter and corrode things much faster, including underwater hardware. liberal amounts of di-Electric grease is a cheap insurance solution(once everything is cleaned up)

04-14-2011, 01:59 PM
Good point, Wakescene.

The PO on my boat had left the (non-breathable) cover on tightly one winter. Significant moisture got in the boat, leaving behind mildew and surface corrosion - and some poor electrical connections. Dielectric grease would have prevented my electrical issues.


04-14-2011, 03:18 PM
Frank, I agree your approach is the right one. I was looking for the lazy boy work around. I do not think that my approach is smart for anything other than a short term band-aid. In the long run it only hides a symptom of a problem that will only get bigger over time. Eventualy showing up in some other unpredicted way...perhaps hazardous...worst case ... perhaps grounding the whole boat through a 10 gage wire. Humm!

02-04-2012, 07:37 AM
Bringing up an old thread... I have a 95 Maristar 225 w/ 350 tbi. At the end of last season I was starting to have grounding issues as well. Oil pressure gauge didn't work, PP (aftermarket) was shutting off and on, voltage meter was varying, radio acting funny. The best idea from reading multiple post was to run a large wire (they had a clearance at West Marine and picked up 4 gauge for .25 cents/foot!) and a terminal block.

There are 4 wire clusters in the dash and they all have grounds. I cut the ground wire in each cluster before the connector and wired it into the terminal block. This seemed logical. However, I am having a few issues. The fuel gauge and the bilge pump don't work. I rewired everything back up the way it was and the fuel gauge and bilge pump work again, however, have not solved my grounding issue...

There is some logic in the wiring system that I obviously don't understand, and I feel like I'm getting over my head. Does anybody have any insight into this?

At this point the only option I know of is to return to the original configuration, clean the connectors, and hope for the best. I also wanted to document on the board that the simple idea of running a new ground wire and terminal block may not work depending on your boat...