Starter Slave Solenoid

[FreeBeeTony]

Is the slave solenoid a "mechanical" device?

Seems mine gets hung-up sometimes.
I am getting about 9.5V to the solenoid w/ the key in the start position but it does not "close". I then connect battery voltage to the yellow/red wire coming from the key switch with the key in the off position, and it "closes" and the starter engages......after I do this I am able to start the engine with the key for the rest of the day.

As another test I disconnected the coil wire and cranked the engine with the key while monitoring the voltage on the solenoid.........was 9.5V and the engine was cranking.

Do I have an intermittent slave solenoid???

Seems like once I jump it one time in the morning it will crank fine for the rest of the day using the key.

 

[stonyloam]

Re: Starter Slave Solenoid

It is an electromechanical device. A low amperage current from the ignition switch activates an electromagnetic coil that causes a set of high amperage contacts to close that provide a high amperage current to the starter solenoid which in turn energizes an electromagnet to close contacts capable of carrying very high amperage of the starter motor. You should have full battery voltage at the y/r slave terminal. You may have a bad contact on the ignition switch or a corroded wire connection that reduces your voltage. It could very well be that it "sticks" a little when it is "cold" it takes a little more voltage to close the contacts properly, and as it warms up it works a more freely. I would try cleaning up the y/r wire connections, all the way back to the ignition switch. Measure the voltage at the switch, should be 12V. good luck.

 

[FreeBeeTony]

Re: Starter Slave Solenoid

I measuered the voltage at the switch and it was >12V.......also measured the resistance bewteen the switch and the solenoid and it was <1.0ohm. The impedance of the low current side measured to be ~2.5ohms.....this voltage divider would cause the 9.5V I measured at the solenoid......is that 2.5ohms correct?

 

[stonyloam]

Re: Starter Slave Solenoid

Seems mine gets hung-up sometimes.
I am getting about 9.5V to the solenoid w/ the key in the start position but it does not "close". I then connect battery voltage to the yellow/red wire coming from the key switch with the key in the off position, and it "closes" and the starter engages......after I do this I am able to start the engine with the key for the rest of the day.

As another test I disconnected the coil wire and cranked the engine with the key while monitoring the voltage on the solenoid.........was 9.5V and the engine was cranking.

Hitting the start at the key should be exactly the same as connecting battery voltage to the Y/R terminal. Both should be battery voltage.

You are getting a voltage reading of 9.5 volts while cranking because the heavy current draw of the starter drops the battery voltage.

 

[FreeBeeTony]

Re: Starter Slave Solenoid

Hitting the start at the key should be exactly the same as connecting battery voltage to the Y/R terminal. Both should be battery voltage.

You are getting a voltage reading of 9.5 volts while cranking because the heavy current draw of the starter drops the battery voltage.

But is the impedance of the slave solenoid 2.5 ohms correct?

 

[stonyloam]

Re: Starter Slave Solenoid

I am afraid that I don't know the impedance. The y/r terminal should still read battery voltage.