VP trim fuse burning out

[Bobo87]

I have a 5.0 liter v8 VP in my 2007 212 and the fuse for the trim keeps failing. It appears to only occur when to boat is on the water bearing driven for my mechanic cannot replicate the issue in the shop. On the trailer or at idler speed it functions fine but again during normal operation the fuse blows. It is a small 10 amp fuse of which I have purchased plenty due to this issue. Has anyone else experienced a similar problem or have a suggestion on what could be causing this issue? I have had the boat for five years and this is a new issue. No recent changes to the anything electrical on the boat.

[stifflkd]

I am guessing the fuse you are referring to is the glass tube or blade type located near the helm? This one is between the trim switch and the relays that drive the trim pump. I can't explain why it would fail under load but it sounds like your tilt trim assy is fine. Does it fail trimming up or trimming down. Maybe one of the relays needs to be replaced.

[Bobo87]

The fuse is a small red 10Amp blade in the fuse box on top of the motor. Since I start out in the down position it is failing when moving to the up position while planing off. Is there a way to test the relays or do you just replace them?

[kas232ca]

My guess is that the pump is drawing too many amps while running underway, blowing the fuse. If you are not the original owner, I would first check to make sure a 10A is the correct fuse.

[Bobo87]

While I am not the original owner I have had the boat for 5 years and this is a new phenomenon. There have been no recent electrical changes and the 10amp fuse was confirmed by mechanic.

[Bobo87]

Have an update to my question. The 10 amp fuse is blowing upon activation even when nothing else is running. Tried a 15amp fuse and same issue. However, when I put in a 20amp fuse I was able to get it to work. Kind of nervous to run that all the time. Any recommendations on why the lower amp fuses blow?

[Bobo87]

Well after having mechanic try to replicate my issue, we still don’t know what the problem is. He spent two days solid looking for the issue but came up empty. Lucky for me I only had to pay for a new fuse and half hour of labor. Hoping to try it out this weekend now that the lake is back to normal levels assuming the rain doesn’t hinder plans. Will keep this post updated on progress.

[bcromwell]

Have an update to my question. The 10 amp fuse is blowing upon activation even when nothing else is running. Tried a 15amp fuse and same issue. However, when I put in a 20amp fuse I was able to get it to work. Kind of nervous to run that all the time. Any recommendations on why the lower amp fuses blow?

This is a really good way to burn your boat to the ground, er bottom of the lake. If it's blowing the fuse at 10 amps that mean the either a device on the circuit is drawing to much current like a motor with a bad winding or the wire has additional resistance due to corrosion or physical damage.
Putting in a 20 amp fuse on a wire rated for 10 amp will eventually turn the wire into a make shift light bulb and start something on fire.

You need to find someone familiar with properly diagnosing electrical circuits.

[bruceb58]

That fuse is only for the wires that go through the trim switch. That fuse does not supply the power to the motor itself. Those are the wires which control the coils in the up and down relays.

It likely only blows in either the up or down operation but not both. You should determine which direction the fuse blows in and then trace that wire. It should be green or blue(you can look at the connector next to the relays to be sure). The red wire is the 12V wire.

Just to eliminate the possibility that it's the relays, pull the up and down relays and then operate the switch and see if the fuse blows.

One common thing that can cause a short are wires laying next to the exhaust pipe. If they do lay on it, the insulation can melt and will cause a short. Make sure no wires are on the exhaust.

Another common area is in the throttle/shift control itself. Very easy for those trim wires to get pinched in there.

trimvolvo.JPG

[Big Block Power]

That fuse is only for the wires that go through the trim switch. That fuse does not supply the power to the motor itself. Those are the wires which control the coils in the up and down relays.

It likely only blows in either the up or down operation but not both. You should determine which direction the fuse blows in and then trace that wire. It should be green or blue(you can look at the connector next to the relays to be sure). The red wire is the 12V wire.

Just to eliminate the possibility that it's the relays, pull the up and down relays and then operate the switch and see if the fuse blows.

One common thing that can cause a short are wires laying next to the exhaust pipe. If they do lay on it, the insulation can melt and will cause a short. Make sure no wires are on the exhaust.

Another common area is in the throttle/shift control itself. Very easy for those trim wires to get pinched in there.

trimvolvo.JPG

That's a great picture to put in the document section.

[AsLan7]

That's a great picture to put in the document section.

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Agreed.
Done.

[Bobo87]

Thank you. Definitely a great layout.

[Titaniumboy]

Nice find on the trim pump diagram.

Is this diagram for all Volvo Penta trim pumps, or is it specific to certain models or years?

Aslan, nice addition to the technical section. You might consider editing the post as being for VP only.

[bruceb58]

Nice find on the trim pump diagram.

Is this diagram for all Volvo Penta trim pumps, or is it specific to certain models or years?

Aslan, nice addition to the technical section. You might consider editing the post as being for VP only.

The relays vary over the years....they were in a module and then separate relays. Basic function is the same.

In older Volvo models, the module had a circuit breaker for the control circuit instead of the fuse like newer ones have. Of course this module is hundreds of dollars and a holdover from OMC joint venture days.

One thing I do whenever I buy a boat or a car is I buy the factory service manual. Has all schematics in them.

This is an example of an older Volvo with the module style of relays.

trim old volvo.JPG

[AsLan7]

Aslan, nice addition to the technical section. You might consider editing the post as being for VP only.

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Good point. Thanks.