Fuse blowing new install

Blueone

Blueone

Well-Known Member
SILVER Sponsor
Jan 24, 2007
13,819
Lake Erie, Ohio
Boat Info
2004 420 Sundancer
Engines
Cummins 6CTA 450's
Bennett Fuse blowing new install

I just installed a new M120 Bennett trim tab system on my Sundeck a couple of weeks ago. Everything was working fine until this weekend. After about a half hour on the lake the pump quit working. I checked the 20 amp fuse and it was blown. I replaced it and it blew in just a few seconds of pressing the switches. I don't see anything obvious with connections or the pump.

Any idea of what the problem might be or a way to troubleshoot it would be appreciated

Thanks for your help

Dan
 
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Not sure what the system is but have you any way of spinning the pump by hand ? Any noticeable drag will up the current draw substantially.
Potential debris in it ?
 
Re: Bennett Fuse blowing new install

Sounds like a question for "TabMan"
 
The M120 incorporates what we call a "lockout" control switch that prevents the fuse from blowing if you push one Trim Tab up at the same time you push the other one down. But even though it is protected, you should not really do that anyway.

The first thing to do is to be sure that there are no stray wire strands on the crimped terminals that connect the four color wire harness to the back of the switch that might be causing the short.

One way to test it is to use the power lead with the 20 amp fuse in it to power each of the 4 wires that run to the pump, one at a time. Blue runs the pump forward (tabs down), Yellow runs the pump in reverse (tabs up), Red opens the valve for the port valve, and green opens the valve for the starboard tab. As long as the ground wire is crimped well and has solid connections, whichever wire blows the fuse is the culprit.

Since you are well within our five year warranty, let me know the results and I will be delighted to get you going!

Tom
Bennett Marine
 
Yes one direction at a time when the second fuse blew. It was just a few seconds on each switch.
 
Tabman... I got a few minutes down at the boat this morning. I checked the ground and it is good. Replaced the fuse and pressed the left button that in turn lowered the starboard tab. It went down fine. However it would not come back up no matter how long I kept the switch pressed. You could hear pump running. When I pressed the right switch to lower the port tab the fuse blew instantly.

Does this make any sense?
 
Blueone said:
Tabman... I got a few minutes down at the boat this morning. I checked the ground and it is good. Replaced the fuse and pressed the left button that in turn lowered the starboard tab. It went down fine. However it would not come back up no matter how long I kept the switch pressed. You could hear pump running. When I pressed the right switch to lower the port tab the fuse blew instantly.

Does this make any sense?
Click to expand...


Did you check the back of the switch for any stray strands of wire?

The first symptom of the Tab not coming up could be caused by low voltage to the system when it is under the load of running. It actually takes more power to raise a tab than to lower it.

The second symptom is pretty obviously a dead short in either the switch (that's why we want to check for stray strands) or the port red wire solenoid has a short. You could confirm it is the solenoid by putting the orange power lead right on the red wire and see if it blows the fuse.

Tom
Bennett Marine
 
I didn't have time to take the dash apart this morning. I have the original searay rocker tab switches not yours. And I used the existing wiring harness in the dash and engine compartment to hook everything up. When I was researching the install Bennett told me I might have a low voltage problem with the searay switches and to use some module. He said searay uses it sometimes. Could that be related?
I will try your other suggestions when I get some time

Thanks again for your help
 
Yes, that is possible. The way to test that is to try the hot wire test I mention both at the dashboard and at the pump.

Tom
Bennett Marine
 
I made it to the boat today. I checked the switches at the helm... No stray wires there.

I disconnected 523 the hot wire and connected it directly to each of the wires to the pump using your harness. I mentioned earlier I used Searay's wiring harness for the install.

Yellow - no problem sounded normal
Green - no noise. Didn't blow fuse
Blue - faint humming noise. Didn't blow fuse
Red - blew fuse instantly
 

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Ok, that isolates the problem. The solenoid valve for the port side has failed to a dead short. It can be replaced under warranty. If you send me a PM with your phone number, name and address we can send you a new solenoid and instructions how to change it. When you are done go to this page http://www.bennetttrimtabs.com/pdf/Bennett_Return_Form.pdf print the form and send it back to us with the original solenoid.

But I am concerned about why the valve failed. It could have been from power to it being on for an extended period of time. Check to make sure the switches show no tendency to stick, and check with a meter that the red wire does not have constant current flowing to it.

Tom
Bennett Marine
 
Tom... I tried sending an email but I guess your inbox is full. I sent a request on your website.

I like the idea of just replacing the solenoid over taking the whole unit out.

I will check for the constant voltage.

Thanks again for your help
 
Oops! It was full, but I cleaned it out.

If you like please send it to me and I will personally follow through on it.

Tom
 
Update... I replaced the solenoid tonight in about 5 minutes. Everything is back to normal... Trim tabs work perfectly now. Nice to have the boat back running level.

Tom ...thanks for all your help and standing behind your product without hesitation.. First class customer service without a doubt.

 
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