Caught in an Electrical Heck! Missing wires, etc. etc.

[ScooterMcTavish]

Hello all,

Please be gentle on me. I'm a first time boat owner who has fixed all kinds of stuff before, but am now befuddled with the electrical mess my boat seems to be in.

First off, my boat is a 1986 Glasstream 152 Tempest, with a Mercruiser 120 engine. There is little to no info about these boats on the old Interweb.

I did also go through the stickies about wiring, but unfortunately, most of the images now seem to be gone. I did get the chart for marine wire color standards, but this may be of only limited help.

So after doing a tune up, and getting the engine running well with the help of a friend this weekend, it was now time to look at the other things that were wrong with the boat. This included removing broken switches and fuse holders from the dash, and checking the wiring. Wow, what a disaster.

First off, I noticed the bilge pump has been disconnected, with its wires lying loose in the engine compartment. Understanding these systems, is it safe to say two of the four wires attach directly to the battery, and two run up to the Bilge switch? Oh yes, there were no wires attached the bilge switch, and no spade connectors without a home.

Secondly, the horn does not work, and what I see is the spade connector attached to the back of its fuse holder (orange w/black stripe wire) is lying limp and disconnected midway down the boat. There are also blue and black wires lying disconnected there as well.

Finally, there were also no spade connectors or wires attached to the accessory switch, and there are no spade connectors without a home. There appears to be a few random wires lying loose under the dash.

As a side note, the blower and lights are working - it is the horn, bilge, and accessory systems that appear to be disconnected or inoperative. My power trim is also not functioning properly (down is fine, up is not), though I will continue to troubleshoot this - at least the hydraulics seem ok as the trailering button does raise the engine.

Ah yes, and the only gauge that seems to be working is the temperature gauge (though the speedo may be working too - haven't been in water yet). Oil pressure, fuel, charging, and aftermarket tach all appear to be inoperative. Wondering if this is somehow related to the other issues. I will check the tach and fuel gauges via the info provided in other threads, but don't want to start troubleshooting these if there is a different issue that needs to be resolved first.

And eventually I do want to hook up a stereo, but want to make sure all these other issues are solved first.

 

[glenn property of pam]

well errrr... hmmm where do we start...lol

boats don't really have wiring diagrams especially the older ones but the motor does so that's a good start. Motor wiring and boat wiring do cross in places but its less then you would think. Normally the engine diagram covers the gauges, alarm horn, dash lights then everything else is a simple circuit ran from the fuse panel. Generic diagrams will work fine for items like the bilge pump, lights, etc and there's lots of them on the net. start at the fuse panel and work one item at a time. if you get stuck I will find you a generic drawing or make one.
p.s always clean the main dc neagtive points (buss) as they can mess with troubleshooting and give real strange results.

 

[ScooterMcTavish]

Thanks Glenn,

I've actually replaced all of the fuse holders, assuming by "buss" you meant the fuses/holders.

Think I'll start with the bilge, then the gauges, then the horn. Will check back in as help is needed/hair is torn out.

 

[glenn property of pam]

a buss is just a electrical name for a place where lots of small items connect to the same terminal which is then normally feed by a larger wire. The negative dc buss is probably a copper strip with lots of screws under the dash but there are other designs. Cleaning the connections at the buss is a good idea as they like to corrode and then you get strange results. Nothing like turning on the lights and seeing the gas gauge peg out.

 

[wrench 3]

There should also be a buss connecting the live side of the fuse holders.
In my experience 1986 boats don't usually have a ground buss as such. They don't usually show up until the 2000s. Don't know why it took them that long to smarten up. In the older boats stuff like the bilge pump usually grounds all the way back to the battery. Stuff further forward usually grounds to one of the gauges or they're all connected together with a nut and bolt that just hangs by the wires under the dash.

 

[ScooterMcTavish]

Thanks for the feedback guys. Things are looking up:

#1 - The bilge pump was bad, so I removed it, and found the brown/black wire drops from the dash in back in the engine compartment. Electrically tested ok, and the new bilge is now hooked up and running properly.

#2 - The Oil pressure gauge had a wire loose - a quick plug back in and now I have a functional gauge

#3 - Figured out the horn wires went back to the dash where they were hooked up correctly. Electrical test again showed juice - now have a new loud horn hooked up

#4 - New light pole and a new bulb has all the lights running 100%

Things that still need resolution:

#1 - Fuel gauge is still not working - checked all the gauge connections and they seem tight. Also pulled the sending unit from the tank, and see that the float is working fine - there must either be something wrong in the sending unit, or I've lost connectivity somewhere......

#2 - There is nothing hooked to the AUX switch, and I'd like to hook up both a fish finder and a stereo. Worst case scenario, can I jump off a different functioning ground, and run a wire back directly from the battery to the other side of the switch? Guessing this would need a fuse as well, though I'd welcome a good recommended size.

#3 - I have a mystery pair of wires running back in the harness from my dash (blue and black), both with a round terminal on them (like for the back of a gauge). Any ideas?

#4 - I also have a pair of mystery wires under the dash (black and white), both of which also have a "gauge" style round connector on them. Any ideas here?

 

[ScooterMcTavish]

#1 solved - when I jumped the sender + wire to the ground post, the gauge shot to full. When I detached all wires, I got a broken circuit reading across the sender from the voltimeter. So looks like the circuit is broke somewhere in the sending unit. FYI, I did take it out yesterday, and the float is moving fine.

 

[ScooterMcTavish]

#2 Solved - There was actually the + wire coming off the switch, and I used the untended ground under the dash. Flicked the switch, and the voltimeter read 12V between the wire off the Aux switch and the ground. So fish finder and stereo are now hooked up and working.

#3 were tucked away as they are obviously not needed, and I used the ground in #4 for the aux. The white will be tucked away.

Really, as long as one has a reasonable knowledge of wiring principles, has a voltimeter, and has some patience, the boat is not as intimidating as it looks.

As a tip for others, I ran both the 12V+ and the 12V battery (for clock and presets) for the radio both to the + wire from the aux switch. Although the radio won't remember your presets or the time, at least you do not have to worry about the radio drawing down the batter if the boat sits for an extended period.

 

[riptide09]

You nailed it on the head. Basic knowledge of electrical circuits, volt meter and lots of patience and beer!