Push Button Starter Testing

[Nichole340]

How do I test the Push Button Starter Switch on my instrument panel? I went to my boat yesterday and was starting the engine. Normally I just have to push the button in ever so slightly and the engine starts. This time I had to push the button in as hard and as far as I could and then the engine started. It has the spring back that it always had. Just doesn’t want connect.
I did remove the button from the panel so I could get to the screws that hold the wires onto the switch. I cleaned and tighten them but they really didn’t need it. I also cleaned and tightened the connections at the starter. They were tight, no corrosion.
I’m sorry, I didn’t think to take pictures, but I will when I go back this week.
My batteries are new and fully charged. Everything works fine just the starter button is acting up.
In the mean time, What is the best way to test the switch?
Thank you for the help.

 

[dlochner]

Is this a Yanmar? There's a known issue with the starter that has these symptoms. The problem is the wire that energizes the starter is too small. The cure is replacing the wire with a heavier gauge.

 

[jssailem]

It is a problem that has been discussed here on SBO. Here is one thread. Yanmar Starter Button

To your specific request, if you have the starter button out of the boat. You can create a circuit using your Digital Voltmeter. Set it to measure continuity. Place the red and black test wires on the two contacts located on the back of the switch. Then press the switch button. The DVM will send a low voltage current into one side of the switch. When you compress the switch you close the circuit and the DVM goes from 0 to 1 indicating that there is continuity in the circuit.

While this test shows the switch works or not, it likely will not resolve your problem. As suggested by @dlochner and others look to your starter circuit wiring.

 

[sailme88]

The rubber boot that usually covers the button has a limited life span. The fine cracks might not be readily obvious, but failure means water intrusion.. The buttons are not expensive.. Best to just replace it. Murphy would otherwise dictate a complete failure at the most inopportune time...

 

[jviss]

DVM goes from 0 to 1 indicating that there is continuity in the circuit.

I guess it depends on your DVM. All of mine indicate an open circuit by displaying a "1" as the leftmost digit position, and then zero Ohms, or close to it, when the circuit is closed. It also depends on the range you set. You should set it to the lowest range, or autorange, if available.

Most DVMs also have a special continuity checker setting, and it will buzz when the circuit is closed (we used to call this the "buzzometer"). This handy, as are a set of leads with alligator clips.

 

[Nichole340]

Yes it is a Yanmar Switch and a Yanmar 3GM30F engine.
I did check the rubber boot as well. It shows no signs of cracks and seals tight to the switch housing.
There is no corrosion on the metal button under the boot or on any of the connections.
I will do the continuity check as you detailed this week, just to make certain its not the switch itself. Then look at replacing the wire from the starter.
Thank you all for the help, guidance and links to the other thread. All greatly appreciated.

 

[kloudie1]

Instead of checking ohms with a meter, measure volts at the output side of the switch. If the contacts are bad inside the switch, you may measure great readings with an ohmmeter, but it will show a significant voltage drop when it has to conduct cirrent ..
An ohmmeter uses very low current to measure ohms .. and can be misleading. You should see 12 V at the input side of the switch and very close to 12 on the output side when you push the switch. Re check the input side of the switch as well when pushing since a low reading on input would tell you that you have a bad connection on the supply to the switch..

 

[jviss]

you may measure great readings with an ohmmeter, but it will show a significant voltage drop when it has to conduct cirrent ..
An ohmmeter uses very low current to measure ohms .. and can be misleading.

I don't follow that, unless you are saying the resistance of the switch will change when it has to conduct. Which I also don't follow, unless you're thinking the heat caused by the resistance will increase the resistance.

 

[Rich Stidger]

I don't follow that, unless you are saying the resistance of the switch will change when it has to conduct. Which I also don't follow, unless you're thinking the heat caused by the resistance will increase the resistance.

Here is another explanation-
The switch could have a high resistance through the contacts. When you test for continuity with an ohmmeter, this "high" resistance is not likely to be indicated. A high resistance could be just 1 ohm; that would be enough to cause a voltage drop to the starter solenoid and prevent it from energizing.
So by measuring the voltage at the output of the switch while it is in the panel and connected normally, you should see essentially the same voltage on the output of the switch as there is on the input.
Alternately, you could simply measure the voltage across the switch contacts. Before pushing the switch you should measure your battery voltage. After pushing the switch you should measure a very small voltage- less than 1 volt, and ideally less than 0.5 volts. Any higher voltage drop across the switch would indicate a failing switch.

 

[jviss]

The switch could have a high resistance through the contacts. When you test for continuity with an ohmmeter, this "high" resistance is not likely to be indicated. A high resistance could be just 1 ohm; that would be enough to cause a voltage drop to the starter solenoid and prevent it from energizing.

Rich, I'm playing dumb a little to get to the crux here. But if you know how to use a DVM, and what the switch resistance shoud be, you can certainly do it this way. I would probably leave it wired and measure the voltage across it once closed. Agreed, it should be pretty close to zero, assuming it's energizing a solenoid, not supplying the starter current! Without looking it up, a solenoid should draw a couple of Amps, at most, so to drop 1/2 V you'd have to have 1/4 Ω or so across the switch. All good. That means if you were measuring contact resistance you'd want the lowest resistance range of the meter, which should read to mΩ.

 

[kloudie1]

Some really good meters may be able to discern an extremely small resistance like that, but regular inexpensive meters are much better at measuring volts.. My good meter doesn't go to the boat, so I have the $10 kind there which works very well for the kind of stuff normally necessary there.. Harbor Freight used to give them away with a purchase and a coupon, so I have several ..
7-Function Digital Multimeter (harborfreight.com)
(don't try to clean the contacts with contact cleaner .. the case and switches will weld themselves together)

 

[Calif. Ted]

The switches are less than $10, also available at most auto parts stores here near the harbor.
Cole Hersee Momentary Push Button Switch - Dash Mount, Rubber Boot

 

[JoeWhite]

What happens when you touch the wires of the switch to eachother after disconnecting one from the switch?

 

[Ralph Johnstone]

The switches are less than $10, also available at most auto parts stores here near the harbor.

@Calif. Ted wins the kewpie doll IMO.

I went out of my tree for several years trying to test my starter system and I could NEVER get it to fail when I had the volt meter on the starter relay. A dozen tries at a time and it wouldn't fail. It would always fail when I least expected it.

My problem was not the push button but an accumulation of several small less than perfect contacts which added up to enough resistance to cause a problem.

If you've got the push button out, replace it.

If that doesn't help ............................................

Guaranteed to solve whatever ails your starting relay system.

 

[Nichole340]

Is this a Yanmar? There's a known issue with the starter that has these symptoms. The problem is the wire that energizes the starter is too small. The cure is replacing the wire with a heavier gauge.

What gauge wire should I use to replace the original wire?
Without doing any of the multimeter testing, I have decided to replace the wire to the starter. And get a new switch as well, even if it is my backup.
I cannot think of any circumstance where having a switch that doesn’t start the engine would be good. And I don’t want to imagine having to start the engine while out sailing and not be able to.

 

[Ralph Johnstone]

I have decided to replace the wire to the starter.

Just to be clear, you want that wire to go to the starter relay, not to the starter motor.

What gauge wire should I use to replace the original wire?

You can't go wrong with 10 AWG wire. It's not really the wire that causes the problems as they never see any corrosion within the vinyl jacket, it's the contact terminals on the ends that cause the problems. Using #10 terminals ensures you are using heavier terminals. Place a dab of grease such as Superlube on the contacts to be sure they don't start any corrosion.

 

[Maine Sail]

This may help:

Add starting relay

I would like to fit an additional starting relay as I'm tired of the "hit or miss" starting issue with my Yanmar 2GM20F. Could anyone share their setup wiring diagram with me? Much appreciated. :)

forums.sailboatowners.com

 

[Nichole340]

Reading your link (thank you very much by the way)….
From your response #18 ( These factory start relays are usually located right below the starter motor bolted to the engine block. You could pay Yanmar about $80.00 for one or grab one at any auto parts store for about $15.00 to as much as $34.00 for a premium Cole-Hersee.)
Am I correct, that if I get the Start Relay and mount it at the starter…..I would the have to splice a length of wire to each of the 3 wires (Red, White, Blue)that are in the 3 wire connector just before the starter now, from the push button.
Then connect them to the relay and from the relay to the starter.
This would eliminate the 3 wire butt connector, which I think is the problem all along. And in essence make a solid run of wires from the button to the starter.
I am sorry I don’t have a photo to show you but I will get one.

It took me a while but I did find a picture from this site of the very same butt connector I am referring to. It is the same 3GM30F Yanmar as mine. And the only connector, I can see, from the Push Button to the starter. Thats why I feel it is the issue. Red arrow, I added, shows the 3 wires from the push button.
I hope I have this right and you can understand my logic.

 

[cagreen75]

The easiest way to test the switch is to get a short piece of wire the same size as the wire on the push button switch, turn on the key, and use the wire to jump the two terminals on the switch. If the starter turns the engine over the switch the switch is bad. If the engine does not turn over then there is a wiring problem between the switch and the starter as others have suggested here.

 

[NYSail]

Jump the wires behind the switch.... Simple test. If its the switch the engine will start, if its the harness it won't. Then more to the starter and jump it there.... it it starts immediately, it is the harness and you can either add a new wire or what most do is add a relay. I added a relay to my 3HM35F and never looked back.

Good Luck
Greg