I really need help getting my starter to work!

[GRWeldon]

Guys,

I've been struggling now for months trying to get my 350B starter to work.

I've replaced a front wiring harness and the starter/solenoid. I've done a bunch of continuity and voltage checking using the tech manual and wiring diagram. I've found that I've got a bad diode in the alternator, but that won't keep the girl from starting, just from charging, eh?

I've bypassed the neutral safety switch, cleaned the ignition switch and push-button switch. I have battery voltage at the solenoid "S" terminal when the ignition switch is on and the push button is pressed, however, the starter won't engage.

I've manually tested the starter by connecting the large lug on top of the solenoid to the bottom connection to the starter and the starter spins, but the solenoid doesn't engage the starter drive. Keep in mind that this is a brand new starter and solenoid (well, four months old but hasn't cranked her over yet).

I'm at my wits end and I need to use my crawler.

Can somebody tell me what I need to do to check if the solenoid is bad because I think it is, even being brand new. I'm about to pull out what little hair I have left. Please help me if you can!

Thanks folks,
Glen

[shinnery]

I would say to try connecting between the large battery terminal at the solenoid and the start terminal at the solenoid with something like a large screwdriver. If it does not engage you have a bad solenoid. Try not to damage the threads on the terminals with the arc when you jump across them.
Bryce

[GRWeldon]

Thank you.... I've done that. Not even a spark....

[DrLoch]

If you've connected a lead from the top lug of the solenoid to the lower lug which runs into the stater motor and the starter motor spun you've effectively bypassed the solenoid and the motor is fine. I sounds like the solenoid itself is bad brand new or not. The solenoid is what advances the drive into the flywheel and then a large washer inside the solenoid connects battery feed lug to the starter motor lug which then spins the starter motor.

[Stan Disbrow]

Hi,

The solenoid has a coil which produces a magnetic field when energized which then pulls the iron core to engage the pinion gear into the ring gear. At that point, it also actuates a switch inside the starter to put power to the starter motor. Or, at least I think we are discussing this style starter, known as a Delco style.

If the solenoid coil is open, it won't move and nothing will happen. Does not matter if you are using the starter button, key switch start position (whichever your machine has), or a screwdriver jump.

Since the solenoid will not move, and a direct connection to the starter motor results in it spinning, your solenoid coil is either open, or the iron actuating rod is jammed up.

If the starter makes a clunking noise when the solenoid is activated electrically, that would indicate the coil works, but the internal switch is not. If it does not make any noise, the coil is open.

As far as electrical troubleshooting goes, there are three parts to it. Voltage, current and resistance. You have to check two of the three to know what is going on. You have done voltage, and have it on the solenoid. But, you need to either check resistance or current.

Resistance is easier, with no voltage on the terminal, use an ohmmeter on it and ground. It ought to be low, showing coil resistance. If it is high, then it is open.

For measuring current, you have to pull the wire off and connect an ammeter in series between the wire and the lug, then hit the starter switch. If there is no current flow, then the coil is open.

I have an inductively coupled ammeter for troubleshooting this sort of thing. You just lay it along the wire and see what it reads. Great for starter and charging issues. They are available at any auto parts stores.

Oh, and an alternator has three phases, so one diode out will still charge, but at only 2/3 the normal high current. That one can wait.

Stan

[jthornton]

If you connect 12v positive to the terminal that the red wire in the back of the photo (arrow points to it) and the solenoid is grounded to the frame the solenoid will pull in if it is good. When the solenoid pulls in it connects the big 12v wire to the starter and the starter should spin. If you have a 4 wire solenoid you may be picking the wrong terminal.



JT

[GRWeldon]

Thank you Stan. This is awesome info and helps immensely.

If the solenoid is bound and can't move at all (certainly possible) will it make a noise when current is applied? I'm guessing not, thus the need for an ammeter...

[GRWeldon]

If you connect 12v positive to the terminal that the red wire in the back of the photo (arrow points to it) and the solenoid is grounded to the frame the solenoid will pull in if it is good. When the solenoid pulls in it connects the big 12v wire to the starter and the starter should spin. If you have a 4 wire solenoid you may be picking the wrong terminal.

JT

JT...

In your picture it looks as if you have something connected to the "R" terminal on the solenoid. Is this just an illusion and the wire is actually connected to the large lug with the other red wire?

My starter has nothing attached to the "R" terminal...

[Stan Disbrow]

Hi,

If the solenoid is mechanically hung, it might make a noise just as power is applied, or it might not. Depends on if it can move a bit, or not at all. A clunk is about all one might expect. DC doesn't 'hum' a coil the way AC does.

The R terminal is for another switch inside the starter for it to apply 12v from the battery across the ballast resistor ahead of a 6v coil. Early 12v systems still used 6v coils and the R terminal compensated for voltage drop on the battery due to the load on the starter. The ignition switch juice goes thru the resistor, the the R terminal juice goes straight to the coil (only while the starter solenoid is engaged, then it opens back up).

Not applicable on a diesel, of course. And, with modern high CCA batteries probably not needed on gassers either, as high CCA batteries do not drop voltage nearly as much as the old batteries did.

Stan

[jthornton]

JT...

In your picture it looks as if you have something connected to the "R" terminal on the solenoid. Is this just an illusion and the wire is actually connected to the large lug with the other red wire?

My starter has nothing attached to the "R" terminal...

It's not illusion the wire that comes from the starter switch is connected to the far #10 terminal. The large terminal is 12v right from the battery. I'm not sure what terminal name it has on it.

http://www.agcoauto.com/content/news/p2_articleid/254

My JD310A backhoe has the R terminal and it is on the outside with nothing connected to it, only the inside small terminal is connected to the start button.

JT

[GRWeldon]

OK...Thank you very much guys. I think I have enough to work with now. I'll be at the farm tonight and I'll pull out the meter again.

One more thing... how can I test a solenoid when I've pulled it off of the starter? I know, there's probably enough information given already but I just want to make sure...

I'm not really good with electricity and sometimes I need to be spoon-fed...

Thanks y'all!

[Stan Disbrow]

Hi,

I never know how much to say. Being a EE by trade, I can become pretty long winded. But, You Asked For It!

One of the solenoid coil leads will be hooked to Ground. The other is hooked to the S(tart) terminal.

Now, the question is: is the Ground side hooked to the solenoid case, or does it have a strap-like lead hooked to a ring terminal lined up with a starter mounting bolt?

I have seen it done both ways. The case Ground connection is more common. In any case, hooking up power between the S terminal and Ground ought to do something.

So, you need a battery charger, a spare battery, or some hook-up leads to the crawler battery to test the solenoid.

I would have it unhooked from power and use an ohmmeter to check for coil resistance between S and Gnd before I even unbolted anything. Keep in mind, an ohmmeter reads Millions of Ohms when open. A coil ought to be anywhere from a few ohms to a few *tenths* of ohms. Not millions of them.

Most modern multimeters sport a Low Ohms setting with a Continuity Beeper tone. Use that if your meter has it.

Make sure there is no battery voltage first. Power kills ohmmeters. They way they work is to push a small current, low voltage, out one probe to use as reference. Then calculate and display the ohms. Any other power present is not good. I always check for voltage first, then switch to ohms. Saves meters!

If the ohms test fails, there is no point in jury rigging 12v to test it.

Stan

[DrLoch]

Stan, nice job. To me all the symptoms thus far point to the solenoid, but stranger things have happened.

[GRWeldon]

Thanks Stan. Just for clarification, my 350B is a diesel. I checked a solenoid on Thursday (not the one in the tractor) by using jumper cables and the tractor battery. Negative was connected to the solenoid case and I applied the positive to the "S" terminal on the solenoid. Got a small spark at the "S" terminal but no solenoid action. Same with the big lug at the bottom. Same when positive was applied at the same time to both the big lug at the bottom and the "S" terminal. I assume the solenoid is bad.

I'll check the ohm reading.

I must have a meter (electronic) that is protected from current when checking ohms. I did a bunch of my continuity checking with the battery connected and to the best of my knowledge, the meter still works. I'll avoid using it in that manner from now on.

Thanks for your help! I am going today to check the solenoid on the machine.

[jthornton]

I would make sure the solenoid "can" move mechanically. You might take the solenoid off the starter and make sure it has all the parts and that the center indeed does move in.

JT