Intermittant low voltage at selonoid

PiratePast40

Lieutenant Commander
Joined
Mar 21, 2009
Messages
1,734
Once in a while, getting a "click" at the selonoid. Try it a few more times and it'll crank. Motor is a Volvo AQ130D. This doesn't happen all the time, just once in a while. Measured the voltage at the seloniod start connector and voltage is 12.5 when it cranks and around 7 when it doesn't. Allways have full voltage at the main power lug on the selonoid. I've backtracked the wiring and taken measurements at the disconnect from the engine wiring harness. Allways have full voltage at the selonoid start connection from the forward harness (switch). Also allways have full voltage at the wires connector to the selonoid (when disconnected). I've tried this several dozen times to make sure. It would appear that I've ruled out this wire but it doesn't make sense that I sometime loose voltage at the selonoid but not from the start circuit wire. Changed to an electronic pickup so the ballast resister is completely removed from the system. The wiring is extremely simple so you'd think it's a no brainer. A single wire from the switch to a connector on the selonoid (there's only one connection so there is no resister bypass lug) and the main power lug from the battery. I've allready replaced both battery cables as well.

It makes perfect sense that the selonoid won't kick in when there's low voltage but why do I only see the low voltage at the selonoid itself?
 

futz

Banned
Joined
Jun 22, 2009
Messages
180
Re: Intermittant low voltage at selonoid

disconnect the battery follow the neg cable to the ground at the block, clean shiny clean the block, the stud, and the end connection.

Follow all the positive, connections and clean, don't forget the starter connections.

Clean all the solenoid connections remove the solenoid from the mounting bracket and clean the base of the slav, and the plate so there is good contact.

Now try it maybe the problem will be resolved.

If not replace the slav solenoid, could be bad.
 

PiratePast40

Lieutenant Commander
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Mar 21, 2009
Messages
1,734
Re: Intermittant low voltage at selonoid

I've allready replaced the battery cables and that included wire brushing and cleaning all connections at the starter and on the block. It doesn't have a slave selonoid so removing the selonoid would include pulling the starter. The starter was rebuilt about 6 weeks ago.

What's confusing is that the drop can only be measured at the selonoid lug and doesn't occur in the wire or at the battery lug.
 

flargin

Chief Petty Officer
Joined
Aug 13, 2008
Messages
540
Re: Intermittant low voltage at selonoid

I would say you have done a very nice job of isolating a bad solenoid.
 

PiratePast40

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Messages
1,734
Re: Intermittant low voltage at selonoid

I would say you have done a very nice job of isolating a bad solenoid.

That's one of the options I was thinking of but was looking for confirmation. Just curious, what would be wrong with the selonoid? Shorted winding, sticking magnet, gremlins?

Not that it matters, but the selonoid is relatively new and was "marinized" when the starter was rebuilt about 2 months ago when the engine was out.
 

flargin

Chief Petty Officer
Joined
Aug 13, 2008
Messages
540
Re: Intermittant low voltage at selonoid

That's one of the options I was thinking of but was looking for confirmation. Just curious, what would be wrong with the selonoid? Shorted winding, sticking magnet, gremlins?

Not that it matters, but the selonoid is relatively new and was "marinized" when the starter was rebuilt about 2 months ago when the engine was out.

It may just be a bad solenoid out of the box. It is possible the solenoid is sticking as it is pulled into the contacts, and thus it does not get a solid connection.

Solenoids go bad for a number of reasons.
1. if the power going to the solenoid is too low, it will not fully close and you will overheat the solenoid or wipe out the contacts... may want to check your starter switch and neutral switch that they are not a little flaky. you did say that you replaced wires... you may have killed it with previous bad connections... that is a normal problem.
2. mechanical wear... unlikely here but the slamming of the solenoid can start to break apart the solenoid/connections
3. overheating/overvoltage too much power ... unlikely since it is new.
 
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