Help with electrical diagnostic!

SteveRay

Petty Officer 1st Class
Joined
Oct 20, 2004
Messages
338
Seems I have a loose wire somewhere. Was out on the water yesterday and boat ran great. However, after being anchored for a bit, I went to turn the key and nothing happened!! Had plenty of juice, all other accessories were working.
Opened up the hatch and looked for loose wires and didn't see any. I may have touched the right one because after that it turned over/started no problem. This happened twice.
Somebody point me in the right direction please!

Thanks in advance!
 

Bondo

Moderator
Staff member
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Apr 17, 2002
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71,148
Re: Help with electrical diagnostic!

The Only Way I know of to find that kind of Gremlin is the Shake, Wiggle,+ Pull Test.........

It's more of a Chance encounter, than a Scientific approach......
 

burroak

Senior Chief Petty Officer
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Mar 29, 2007
Messages
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Re: Help with electrical diagnostic!

It may be time to set aside a Saturday and start at the battery cleaning, applying dielectric grease, and re-tightening each terminal in the starting system. As was stated before, it will be a random fault, but giving the system a complete rejuvenation will correct it and you will have eliminated the next point of failure.
 

SteveRay

Petty Officer 1st Class
Joined
Oct 20, 2004
Messages
338
Re: Help with electrical diagnostic!

Awesome! The battery was bought last season and all terminals are really clean and tight. So I guess I am headed out right now armed with service manual and your info under the dash
Thanks again guys and have a great weekend
 

SteveRay

Petty Officer 1st Class
Joined
Oct 20, 2004
Messages
338
Update: Electrical Help AGAIN.....

Update: Electrical Help AGAIN.....

Thought I had this one but it seems it's rearing it's ugly head again....
Went out today and the boat started right up, no problems. Went to head back in and NADA....Looked around and couldn't find anything loose, battery cables are clean and snug. Wiggled teh throttle in thoughts of the neutral safety switch being stuck and nothing.
All evidence seems to be pointing to the solenoid correct?
The starter is only a few seasons ols and clean as a whistle...Is this normal?
 

SteveRay

Petty Officer 1st Class
Joined
Oct 20, 2004
Messages
338
Re: Help with electrical diagnostic!

Don's links must be bad.....only the first picture is showing up.....HELP!
Going to Napa today to buy a test light.

Hopefully this is my last question.......It appears that the symptoms would have to be present in order to troubleshoot according to Don's guide correct?
 

Reel Poor

Vice Admiral
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Jan 29, 2005
Messages
5,522
Re: Help with electrical diagnostic!

Here is Don's post. I add a couple of pic that should help ya.

Since the Search function just can't find this previous post, here it is again.

So you hit the ignition switch so you can go home and either nothing happens, or you here a click from the engine, but the starter doesn't crank......... Now what ?
If you have a test light, you can find out in only a few minutes what the problem is. I like test lights because they are faster and easier to use than a meter. A meter will work fine for all the tests.

49586.JPG


Start by checking that you have a good battery that is fully charged, clean tight battery connections with good battery cables of the proper size. This includes both the positive and negative cables. If you don't have this to start with, the rest of the tests are worthless.

So, where do you start looking for your no start condition? That depends on what you hear. If you DO NOT hear a click, we will start at the ignition switch, if you hear a click, we will head for the engine compartment.
Let's say we have no click, and the shifter is in the neutral position and we have already tried wiggling the lever to be sure it's in neutral.
Grab your test light and head for the back of the instrument panel. Hook the clip to a good ground (usually on the fuse panel).
Now, touch the light to the B terminal on the ignition switch ( big red or red/purple wire) the test light should light. Now move the test light to the S terminal with the yellow/red wire and have someone turn the key to the start position. The test light should light, if not, you need a new ignition switch.
Let's say it lit up, so the switch is good. While the problem could be the neutral safety switch, it's a real pain to get to in order to test it. So let's check to see if we have power going through the neutral safety switch.

Start%20wiring.png


Time to head for the engine compartment.
Now, locate the slave solenoid or relay, on the engine. Notice the 4 wires to it?

StarterSolenoid01.jpg


or for those with a Volvo that have a relay instead of a solenoid use this picture.

VolvoPentaStarterRelay.jpg


Hook up your test light again with the clip on a good ground. Now touch terminal C of the slave solenoid with your test light and have your helper turn the key to the start position again. The light should light up? If it did, touch your test light on terminal A, if it lights, hook your test light lead to it, and put the probe on terminal D (the ground) if it doesn't light, then you have a bad ground for the slave solenoid and without that ground the slave solenoid will not work.
If the test light did not light up, then the problem is 1 of 3 things either the connection at the main engine harness plug is bad, or you have a bad neutral safety switch or a bad connection between the ignition switch and the slave solenoid.
If you are at home, this isn't a problem and you can track the problem down. But if you are out on the water what can you do? Simple. Use a test lead on the slave solenoid to jump between terminals A and B or A and C and the engine will crank. Make sure the ignition switch is in the run position and the engine will start.

Ok, lets say when you hit the switch you hear a click from the engine, but no cranking of the starter. Now what do you check.
Simple, back to the slave solenoid on the engine. Hook up your test light clip to a good ground and touch the tip to terminal A, if it lights, touch it to terminal B and have your helper hit the starter switch again. If you hear a click and the light does not come on, then the problem is a bad slave solenoid. If you are out and need to start the engine, you can disconnect the wires from terminals B and C and hook them together and you will be able to bypass the slave solenoid all together and it should work. If not, due to long wire runs, just jump between terminals A and B to crank the engine over.
If the light does come on, move on to the starter solenoid itself.

Starter20Solenoid.png


Touch terminal B on the starter solenoid itself, if the test light lights up, then you have a problem with the starter itself. Time to pull the starter and have it tested, repaired or replaced. If you are out on the water, you may be able to tap the solenoid (Gently, don't want to break things) while holding the switch to the start position and see if it will work. If not, you need a tow.

One other thing to keep in mind when checking with a test light or a meter either one. Check the terminal of the unit itself and also check the wire at the terminal. A corroded or loose wire end could also be the problem.

While this may sound like a lot of work, it only takes a few minutes to check things out.

These pictures are all from Mercruiser, mostly because they are available. OMC works the same, although their slave solenoid is a different kind, Volvo uses a relay instead of a solenoid, but again, it works the same way.
 
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