Deisel Shutdown Woes

[wstockho]

I have a 2005 Hunter 33 with a Yanmar 2GM20F auxiliary. The engine is equipped with a remote shutdown button in the cockpit which, when pushed, energizes a solenoid which in turn dumps the fuel by moving the manual shutdown lever. Problem is, this stopped working a few months ago and now, to shutdown the engine I have to remove the cabin ladder and move the lever manually. I performed troubleshooting with the following results:

The push button switch appears to work. The buzzer sounds when the button is pushed. Battery voltage is available at the switch and when pushed, the output is initially 13.5 VDV, but drops almost immediately to 8.5 VDC.

I lifted the leads from the solenoid and checked the voltage present when the button is pushed. This was 13.5 VDC. I hooked up the solenoid to a separate 12 VDC source and the solenoid worked normally to move the shutdown lever and dump the fuel. I reconnected the solenoid and tried the shutdown button again, but no joy. I measured the voltage across the solenoid when the button is pushed and got less than 1 VDC.

There is a relay in the circuit. I can hear the relay click when the button is pushed indicating that it is cycling as required, but the relay is sealed, so I can't examine the contacts. There is no manufacturer name on the relay, but there is a diagram on the relay that shows it is a single pole, double throw relay with what appears to be a part number of 0331301B made in USA.

It appears that under load, the voltage drops too low for the solenoid to work. I suspect the relay, but haven't been able to find a replacement part on line. Can anyone point me to a source for this relay? My wiring diagram doesn't show it.

Any other troubleshooting tips would be appreciated.

 

[Charles Erwin]

Consider a call to Tacoma Diesel. By the way, consider also remove/test the relay independently so as to to rule out possible poor wire connections?

Charles

 

[wstockho]

Consider a call to Tacoma Diesel. By the way, consider also remove/test the relay independently so as to to rule out possible poor wire connections?

Charles

Thanks! I'll try Tacoma Diesel for the relay. I did try to get the relay out, but had a lot of trouble removing the plug from the relay. I probably need to try harder to pry it apart. Even if I remove the relay, I'm not sure how to test it, since it isn't on any wiring diagram that I have and I don't know what the operating voltage is. It's probably 12 VDC, but I'm just guessing.

 

[Charles Erwin]

If the relay is toast take the relay to Westbay NAPA and see if they can match it up. Maybe as to save a trip over the bridge. By the way there is no doubt it is 12v.

Charles

 

[Bill Roosa]

The relay is most likely a cube about .75" on a side made of black plastic?
The auto industry makes these and as long as it is rated for 12 volts and the correct amps it should work. If memory serves 30 amps is the rating on the solenoid.

 

[kloudie1]

Put spade connectors on a short piece of 12 ga wire and use that to jumper the high current in the plug .. you should have always hot on one lead and the other goes to the solenoid.. the other two are the activating coil . You can figure out which are where by checking continuity on the relay.. two of the pins, the coil connections , should have some ohms.. maybe around 30? the other pair of contacts are the high ampere ones .. where they mate to the plug, jumper across and see if the solenoid activates.. if it does, bad relay.. if it doesn't, bad connection in the high ampere circuit

 

[wstockho]

The relay is most likely a cube about .75" on a side made of black plastic?
The auto industry makes these and as long as it is rated for 12 volts and the correct amps it should work. If memory serves 30 amps is the rating on the solenoid.

You nailed it exactly except it's gray plastic in my case.!
The diagram on the relay shows the number 30 on one of the connections (the line that is switched) so that may be the 30 amp rating.

 

[wstockho]

Put spade connectors on a short piece of 12 ga wire and use that to jumper the high current in the plug .. you should have always hot on one lead and the other goes to the solenoid.. the other two are the activating coil . You can figure out which are where by checking continuity on the relay.. two of the pins, the coil connections , should have some ohms.. maybe around 30? the other pair of contacts are the high ampere ones .. where they mate to the plug, jumper across and see if the solenoid activates.. if it does, bad relay.. if it doesn't, bad connection in the high ampere circuit

Makes sense. I'll give it a try before I replace the relay. Thanks for the tip!

 

[Charles Erwin]

The numbers on the pins are 85 86 87 and 30. They designate the coil pins (85 86) and the switched pins (87 30.)

Charles

 

[Bill Roosa]

To diagnose the solenoid test for a circuit between each terminal on it and the case. There should be very high resistance. if not the solenoid is shorting to ground and needs replaced. if that checks out jumper from a 12 volt source to the solenoid hot and see if it activates. if it does then the solenoid is fine and the control circuit is having issues and you need to focus your efforts there.
the control circut is exactly like a starter and solenoid circuit. You supply a small current via a push button (starter switch) to the relay (starter solenoid) and it closes a contact that supplies high current to the solenoid (starter).

 

[wstockho]

Problem fixed! It turned out to be a bad relay. I got a replacement relay from Napa Auto Parts this morning and popped it in. The remote shutdown now works perfectly. Thanks to all who responded with great advice.

 

[kloudie1]

Excellent!

 

[artboas]

Fyi

Excellent!

Your troubleshooting is an issue that doesn't make sense to people, so I'll explain.
When you measures the voltage at the leads when they were disconnected from the solenoid, you got 12v
Hooking up the solenoid 1v
What this means is that you have a high resistance in the current path.
The meter has a high input impedance, I.e., it draws very little current.
The input resistance is usually in the Megohm range.
So you have very little current drawn by it.
Once you put on a higher current load, the series resistance from your bad upstream connection now forms a voltage divider with the actual load.
That is why the measured voltage drops to 1v
So, when troubleshooting any flaky circuit, always measure with the load attached, which will pinpoint the problem to either a defective device, (solenoid), or bad switch , I.e. no voltage.
On a similar vein, people are often puzzled when they test their flashlight batteries with a meter they read ok, but the flashlight doesn't work.
Reason is that as dry cells run out of juice, their internal resistance goes up.
So, while a low current meter wil read them as fine, once a bulb load is put on, the voltage drops out