Electrical Issues

[J-Rye]

I just bought a 96 Cobalt 233 this weekend. Amazing boat and I couldn't be happier, BUT I need some help diagnosing some electrical issues.

I'm familiar with electronics and using a multimeter, but I was hoping to find some expertise on the forums.

Here are the issues:
1) Tach reads 4500 rpm at all times while the engine is running
2) Docking lights will turn on for 5 seconds, then trip the breaker
3) Interior lights do not turn on
4) Horn doesn't work
5) One of the speakers doesn't turn on, and the antenna is disconnected

Some of the issues are easy to fix, but I wasn't sure if they could be related somehow.

 

[Silvertip]

Re: Electrical Issues

1) Sounds like a sticky tach movement - not electrical. Usually these are not able to be disassembled for repair so they require replacement.

2) Docking lights draw a fair amount of current so either the breaker is too small or there is a short in one or both of the light circuits. Disconnect one and see what happens. If the other one works and the breaker doesn't blow. Reconnect the first and disconnect the second. If the breaker still works ok, I'd suspect it is simply needs to be a larger breaker. If either lamp trips the breaker, that's the circuit with the problem.

3) Interior lights not working means the circuit is not powered. Check for power into and out of the switch. Follow the current until you lose it. Since all lights don't work, it is likely a supply/switch/breaker problem.

4) Same as #3 for the horn. Push the button and check for voltage at the horn.

5) The antenna and speaker are not related. Connect the antenna. Fader or Balance control may be turned down on that channel.

Comment: None of these items appears to be related unless the cabin lights and horn are on the same circuit.

 

[J-Rye]

Re: Electrical Issues

1) Sounds like a sticky tach movement - not electrical. Usually these are not able to be disassembled for repair so they require replacement.

2) Docking lights draw a fair amount of current so either the breaker is too small or there is a short in one or both of the light circuits. Disconnect one and see what happens. If the other one works and the breaker doesn't blow. Reconnect the first and disconnect the second. If the breaker still works ok, I'd suspect it is simply needs to be a larger breaker. If either lamp trips the breaker, that's the circuit with the problem.

3) Interior lights not working means the circuit is not powered. Check for power into and out of the switch. Follow the current until you lose it. Since all lights don't work, it is likely a supply/switch/breaker problem.

4) Same as #3 for the horn. Push the button and check for voltage at the horn.

5) The antenna and speaker are not related. Connect the antenna. Fader or Balance control may be turned down on that channel.

Comment: None of these items appears to be related unless the cabin lights and horn are on the same circuit.

That is great info. Thank you.

As far as the tach is concerned, it is at zero until the boat is turned on. Once running it goes to 4500 rpm and doesn't move. Could it be the tach sensor is bad or poorly grounded/positioned? From your first response it sounds like my ONLY option would be to replace it.

 

[Silvertip]

Re: Electrical Issues

There is no tach sensor. It operates by converting the pulses from the charging system (usually 6 pulses/rev) into an RPM display. All I can suggest is to verify that the connections are tight and not corroded. If the internal light works, then the unit is properly grounded. There is normally a dial on the back of the tach that allows selecting the number of pulses. Turn that dial back and forth a few times and then reset it to the original setting (probably 6P). Sometimes that adjustment gets a little touchy and does weird things. The back and forth movement cleans the internal switch. Tachs are generic and are not terribly expensive so it's not like you have to mortgage the farm to get a new one.