Kohler Command Starter relay

Mike McKown · #1 02-02-2017, 01:36 PM

I'm not sure where to start on this one. This 1864 had the usual click, click starter on it that many have so I installed the relay kit as described in the photos. This is one of several I have done. This is the only one that doesn't behave.

The problem is, the starter mounted solenoid is getting a spike to engage the starter. It is momentary, about every 4-5 seconds, sometimes in a rhythm, sometimes random. Just enough to make a loud scratching sound as the starter drive hits the flywheel.

It doesn't seem to do it when the engine is running at very low speed, nor does it seem to do it when the PTO clutch is engaged. It always does it when the engine is running medium to fast without PTO.

I first tried another relay. No help.

I probed the hard shell connector mounted to the engine (blue wire) and I got a solid, very dim light on a test light with the engine running and switch in run position. I put a VOM on the same circuit. With the engine idling, I got a little less than 13 volts and the starter wasn't energizing. I revved the engine about half throttle, saw 16-17 volts on the meter and the starter started energizing again, all by itself.

If I put the wiring back the way CC built the tractor, there is no apparent problem except the occasional click, click when you try to start it.

I wouldn't think there should be any voltage present on the blue start wire with the key in the run position. Maybe I have a bad key switch because it's bleeding over internally? Maybe the increased voltage when engine speed is increased makes a faulty switch condition worse?

What say you?

PS. This isn't my engine but my engine is wired like this one.

darkminion_17 · #2 02-02-2017, 02:20 PM

Switch switches with one of your other cyclopses and see what happens.

Mike McKown · #3 02-02-2017, 03:34 PM

That is my next move but ...................

DieselDoctor · #4 02-02-2017, 04:39 PM

Check to make sure you have good ground between block and frame, and block to battery. A bad ground can cause feedback issues on any circuit that has potential.

Mike McKown · #5 02-02-2017, 04:46 PM

Quote:

Originally Posted by DieselDoctor

Check take sure you have good ground between block and frame, and block to battery. A bad ground can cause feedback issues on any circuit that has potential.

My thought as well. Thanks. Some previous worker bee has jiggered with one of the wires that goes to the ignition switch but I haven't checked it out yet.

Just trying to gather a few ideas to try before I get my hands dirty.

ccpullin · #6 02-02-2017, 06:23 PM

There is a diode under the blower housing in the starter wire circuit allowing current to flow to the carburetor solenoid while engine is cranking. If the diode is bad current will flow backwards from the ignition circuit feeding the carburetor solenoid back to the starter. Being a small amount of current it will effect a relay installed, but not the starter solenoid when wired to it as factory.

Alvy · #7 02-02-2017, 07:06 PM

I agree with the diode too but am concerned with 16 to 17 volts DC. Should be regulated at high 13 to low 14 ish. Could be issue with voltage regulator

Mike McKown · #8 02-03-2017, 10:43 AM

Quote:

Originally Posted by ccpullin

There is a diode under the blower housing in the starter wire circuit allowing current to flow to the carburetor solenoid while engine is cranking. If the diode is bad current will flow backwards from the ignition circuit feeding the carburetor solenoid back to the starter. Being a small amount of current it will effect a relay installed, but not the starter solenoid when wired to it as factory.

Quote:

Originally Posted by Alvy

I agree with the diode too but am concerned with 16 to 17 volts DC. Should be regulated at high 13 to low 14 ish. Could be issue with voltage regulator

Okay, this all makes sense. Looking at the wiring diagram, I see the two diodes in the circuit and the back feed is possible/likely. When you factor in this little blurb I found, it also explains why there is no problem at low engine speeds (low voltage) and/or with the PTO engaged but the problem begins when the voltage raises too high at higher rpm with no PTO load. Or, the diode could be defective.

Allows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage

Thanks for the help.