Slave Solenoid

[FreeBeeTony]

Was fooling around with the boat today and tried the key in the start position.......engine did not turn over. I measured the voltage on the slave solenoid (yellow wire w/ red stripe) coming from what I believe is the key and it measured about 8.5V. Doesn't seem like enough voltage to "throw" the soleniod........how much voltage is needed? I measured the voltage at the key and it was almost 12V so I must have a drop somewhere...maybe the plug I don't know yet.

Just wondering how much voltage is needed to "throw" the solenoid?

 

[Don S]

Re: Slave Solenoid

There are 2 yellow/red striped wires on the slave solenoid. They should both be seeing approximately battery voltage when in the start position.
Low voltage like you are showing is probably from a corroded connections some where.
Don't forget this how to. http://forums.iboats.com/showthread.php?t=167035, maybe it will help in finding the problem.

 

[achris]

Re: Slave Solenoid

Tony,

How are you measuring the voltage? From terminal to ground or across the 2 smaller terminals on the solenoid? You should be measuring terminal to a known good ground. If you are, then the loss of voltage would be a back/corroded connection somewhere, like the master said.

Chris......

 

[FreeBeeTony]

Re: Slave Solenoid

The voltage I was measuring was the low current terminal. From the terminal to a known good ground and I verified the other terminal was connected to gnd. One of the high current terminals had battery voltage but the other had 0V even when the key was in the start position..

 

[Don S]

Re: Slave Solenoid

Here is an easy way to test your solenoid Tony. Assuming you have a standard solenoid setup like this.

Make a jumper wire and clip on to the positive terminal of your battery. Then touch the other end to terminal C. The engine should crank over. If not, touch it to B (be careful, it will get hot quick and burn you if the engine doesn't turn over.) If the engine cranks over, you need a new slave solenoid.

Again, be careful lightly touching wires, won't tell you much and can burn. Best thing to do with this kind of quick test is to have an aligator clip on both ends of your jumper wire and hook the end your are touching different terminal with to an old screwdriver so it makes good contact. It can burn the tip off of things downstream are bad.

 

[FreeBeeTony]

Re: Slave Solenoid

That seems like a logical test Don, I will try it tomorrow. The voltage I was reading was on terminal C and it was only around 8V.....with the key in the start position.......not sure why I'm not getting battery voltage here.

 

[achris]

Re: Slave Solenoid

That seems like a logical test Don, I will try it tomorrow. The voltage I was reading was on terminal C and it was only around 8V.....with the key in the start position.......not sure why I'm not getting battery voltage here.

The coil in the solenoid has a certain resistance. If you have a resistance in the wiring between the battery and the coil (your terminal C) we have what is called a 'voltage divider'. Based on the voltage you have at terminal C, 8 volts, we know that the resistance in the wiring (connectors, ect) is about half that of the coil, so it's not big, but enough.

Chris.......

 

[JustJason]

Re: Slave Solenoid

to a known good ground

Eagh.... Best way to tell if a ground is good is to voltage drop test the ground lead under electrical load.
For me... I have a 20ft lead of 14AWG wire that I put radio shack aligator clips on each end. Where ever i'm working, I connect 1 of the ends to battery negative, and the other end to my meters negative. A ground may appear good even during a resistance test, but put some juice through it and you might see a different story.

Easiest way to TS what you have is to make a lead up for yourself. Put the meters - on the lead as stated. Then backtrack from your lowest voltage measurement. If you get 8V at the slave terminal, go the the keyswitchs output, if your getting 8 there, then the wire from the switch to the slave is fine. Go to the keyswitches input, if you get 8 there then the problems before the key. If you get 12 at the key but 8 out then you have a bad switch, or bad/rotted wire terminations at the switch.

I can tell you from first hand experience you'll be chasing ghosts by grounding your meter someplace you think the ground it good. Ground it at the battery via a test lead and you won't make mistakes + the troubleshooting goes faster.

 

[FreeBeeTony]

Re: Slave Solenoid

The coil in the solenoid has a certain resistance. If you have a resistance in the wiring between the battery and the coil (your terminal C) we have what is called a 'voltage divider'. Based on the voltage you have at terminal C, 8 volts, we know that the resistance in the wiring (connectors, ect) is about half that of the coil, so it's not big, but enough.

Chris.......

I am by trade an electronics technician so I know what your talking about when you say "voltage divider"...........so are you saying the the 8V is to be expected?

 

[achris]

Re: Slave Solenoid

8 Volts normal??? Definitely not... I would expect battery voltage at the terminal when you turn the key. I was just explaining how you would end up with 8 volts, not saying it's right. Do a volt drop test on each section of the system. Check voltage at key switch terminal, at engine harness connector ect. As an Elect tech I would think this is right up your alley....

 

[FreeBeeTony]

Re: Slave Solenoid

Yes Chris, it actually is right up my alley.........I was about to start checking the voltage at the harness connector at the end of yesterday but ran out of time......going to check that first. I replaced the switch panel in the boat over the winter and may have disturbed something in the harness......

 

[JustJason]

Re: Slave Solenoid

just ground your meter at the battery then backtrack, it goes sooo much faster.

 

[FreeBeeTony]

Re: Slave Solenoid

Problem solved...........not sure why???

I measured the resistance between the switch and tha connector on the harness....0 ohms

Then re-connected the connector and measured the resistance between the swtich and terminal C and 0 ohms again.

Then measured the voltage at the switch (yellow/red wire) and measured battery voltage.

Then measured the voltage at terminal C and measured ~8V.

All the while the engine was not turning over.

Then tried Don's test and jumped the battery to terminal C........the engine turned over!!

Then tried the key again and the engine turned over!!!!

Is the solenoid a mechanical device? Maybe it was "stuck" and needed a little more voltage to close it the 1st time?

 

[Don S]

Re: Slave Solenoid

You might check the connections on the neutral safety switch, it's between the key switch and the solenoid.
Yes, the solenoid is mechanical. The power going through the coil makes a magnet and pulls the contacts together.
Where did you have the ground wire of your meter when you got the 8V on terminal C ?

 

[FreeBeeTony]

Re: Slave Solenoid

Hi Don.......I'm embarrased to say the neutral safety switch is not connected.

I had the gnd wire of the meter was connected to the stud coming out of the middle of the carb......

 

[Don S]

Re: Slave Solenoid

I was curious if you had your meters ground wire on the D terminal of your solenoid.
Now that it's working again, it makes the troubleshooting a bit tougher.
Did you take the main harness plug apart and check the terminals?
Might even check that splice where the neutral safety switch was. Have had a few that were all corroded.

 

[FreeBeeTony]

Re: Slave Solenoid

It's working again......but the voltage still read the same..........could've even been lower while cranking...........it seems llike the solenoid was stuck.

The corroded splice theory is interesting........never thought of that.........just need to find the splice.....

 

[Don S]

Re: Slave Solenoid

It may very well be a stuck soleoid. I would bet if you take the wire off the C terminal and then check the voltage, it should come up to battery voltage. The voltage drop may be coming from across the coil of the solenoid.

 

[FreeBeeTony]

Re: Slave Solenoid

Well......can't fix if it ain't broken.............guess I will leave well enough alone for now.