Voltage drop on dash gauge and alarms
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=2117
Printed Date: November-23-2024 at 4:15am
Topic: Voltage drop on dash gauge and alarms
Posted By: Guests
Subject: Voltage drop on dash gauge and alarms
Date Posted: July-20-2005 at 8:20pm
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I'm looking for suggestions about an electrical problem on my 86 Ski Nautique with 351 and electronic ignition.
Scenario: The volt meter gauge is registering about 1 volt less than what is being output by the alternator (when running) or the battery without the engine running. I've tested the battery (only one year old and it starts the boat no porblem) and the alternator (about 13.7V at the terminal). I've also tested the meter and it is reading correctly about 1 volt less than already mentioned. Additionally, when I turn on the blower or lights, the voltage light comes on and the alarm sounds showing 11.7 volts (agrees with waht is on the dash volt meter and my portable volt meter), but the alternator and battery still show 12.7-13.2 volts. I've also checked the power to the switches and it's the same as the battery voltage. The power from the ignition switch seems to be about .5-.8 volts less than the battery or alternator. Additionally the boat starts great and runs great other than this. If it didn't alarm, I would have guessed that it was the voltage gauge. I think it might be the ignition switch. This is a new problem within the last two weeks. Questions: 1. Is there a voltage drop across an ignition switch and if so how much? 2. Is there something else I should be looking at? 3. Anyone else had this problem and what did they do? |
Replies:
Posted By: Siveck
Date Posted: July-21-2005 at 12:04pm
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Maybe it has something to do with the fact that these boats have the guages and accessories wired in a chain. I think that this is fairly common with these boats. I will eventually rewire mine as I don't really like the way that the original wiring was laid out. ------------- 1975 Ski Nautique "Small Letter Boat" |
Posted By: David F
Date Posted: July-21-2005 at 12:15pm
| More likely than not, it is probably a grounding problem partly due to the guages being wired in series as Siveck mentioned. Run seperate ground wires to each gauge from the main ground wire or clean up and tighten all the ground points. |
Posted By: Guests
Date Posted: July-21-2005 at 8:20pm
I have an 87, with the same problem. It's the red positive wire that runs from the ignition switch to power the + buss bar. If you take a look under your dash you will see that there is a larger (10 guage) wire that feeds the - buss bar (black wires). Then look at your + buss bar (red wires). Mine has a small (possibly 14 guage) wire feeding all the accessories from the ignition switch. A meter reading on both sides of this wire confirmed that it's not large enough to carry the load, and you can see the voltage drop too. Turning on your blower only aggrivates the problem. The fix- replace with a larger wire to carry the load. Sounds easy, but when you take a look at where it is you'll understand why I haven't done it yet. I'm waiting for colder weather! I'm also going to solder on the terminal ends. Refer to the dash print in the reference section and you'll be able to see the wire mentioned above. 
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Posted By: pmt2234
Date Posted: July-21-2005 at 11:18pm
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My 84 had a number of similar problems with the wiring. I discussed it with the EE's at work, and the following steps have cured what ailed me:
1.) Solder up every crimped or slip together connection. Do it right over the corrosion. That was their advice and i'ts worked great for 5 years now. 2.) Disconnect the multi conductor plugs and coat the pins with tune up grease. The voltage drop from my battery to my gauges is now 0.3V, and from my dash to the + terminal of my coil 0.2V. I haven't added any new or bigger wires, I just fixed up the old ones with good results. |
Posted By: Kaiahso
Date Posted: July-24-2005 at 10:02am
| Thanks for the advice. I'll give it a try. I'll post what I find. It is the original wiring and I'll let you lnow what I discover. |
Posted By: Kaiahso
Date Posted: July-30-2005 at 10:16am
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Well I figure it out. I replaced the ignition switch and the volt reading went from 11.9 to 12.2V. I also cleaned the ground contact on the engine leading to the dash, which added .1V (12.3V). I replaced the Red + lead wire from the ignition circuit breaker to the switch and added .1V (12.4). I tested the battery Voltage (12.57) and hooked up temporary wires to the dash and was able to get .1 more volt. I decided to add an additional ground wire between the - bus bar and the end of the ground wires by the volt meter. I placed a Y connection so the volt meter reads from the bus bar and the instruments get an additional ground.
I removed the temporary battery wires. I get a voltage of 12.5 at the volt meter and across all gauges without running the engine. I get 13.5V while running, 12.8 volts running with the blower and all accessories turned on. (total time working 1.5 hours) It was definitly the ground wires. Problem fixed (and my dash light are 50% brighter too). Thanks for everyone's input including Vince at SKIDIM. |
Posted By: Keith
Date Posted: August-23-2005 at 3:16pm
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I had a similar problem with my '86 Nautique that wasn't fully realized until after David F. repaired my alarm module and ready this discussion. I found a loss of up to 1.75 volts through the orginial ignition!
In hind sight, this should be the first place to check for electrical problems. After all, just about everything is wired through the ignition. A loss of volts there will affect the starter, gauges, lights - everything that works at 'key on' status. -Keith ------------- Former: /diaries/details.asp?ID=6170" rel="nofollow - 97 Sport Nautique 1994 Ski Nautique 86 Silver Nautique 79 Mustang |
Posted By: JEFF KOSTIS
Date Posted: August-24-2005 at 1:23am
Isnt it amazing on how inadequate the wiring is in boats?! ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |