Starter circuit problem

[Laneman950]

Engine clicks but won't turn over. Battery is reading 12.2 volts. I cleaned the cable ends neg & pos, checked the neutral switch. Here's the weird part. I have 12 volts at the starter terminal. When I turn the key to the on position it drops to 4 volts. The battery water level is good, purchased in Feb 07. Any ideas? Ignition switch?

 

[wushaw]

Your voltage drops to 8v when you turn the key on....bad battery.

Water level is one thing...electrolyte level is another, water level can be up but it is not a real good indicator of what the condition of the battery is.
Get a electrolyte level checker to see what state the battey is in.

Get a set of jumper cables and jump it off to see if it will start or put a battery charger that has a start feature and start the tractor then check what the alternator output is to verify the alternator is good/bad. 13.5 -14.4 is average for alternator output.

 

[bncsauve]

I agree, very likely bad battery, but, possibly shorted starter. If the wires get hot when you try to crank it, it could be the starter.

 

[RickB]

Do the voltage test DIRECTLY ON THE BATTERY POSTS while attempting to start. I believe you have a bad connection at one or more battery cable ends or perhaps a cable with internal corrosion. Find out where the voltage drops. Don't condemn either the battery or starter without using a battery of known quality or otherwise confirming starting voltage and amperage. Cable connections need to be clean & bright. The info you have provided so far can be caused by a bad starter, battery, cable or connection.

 

[Laneman950]

The voltage stays at 12.2 when tested at the battery posts and the key is turned on. When tested at the starter end of the positive cable and a good ground, it drops to 4v when I turn the key to the on position (not the start position)

 

[RickB]

That's a connection or cable problem, not a battery or starter problem.

 

[patrick_g]

Rick, You are the guy I want helping me when I run into a difficult electrical problem. You were definitely not like one of the blind men with the elephant!

Where were you when I needed you? I was driving the tractor out in a pasture and some folks walked up to talk to me so I turned it off and it refused to crank when I wanted to start it again. The idiot lights seemed normal but the starter didn't even twitch. All connections on the battery and starter were clean and tight.

A stick (piece of brush sticking up that escaped the full wrath of the brush hog) had "magically" found a way to stick up into the "works" and hit a starter solenoid terminal and cause an internal bare wire to shift position just enough to short to case. I didn't discover this until I removed the starter to replace it or have it rebuilt. Being curious I opened the starter to look inside. When I saw the wire I just chuckled and bent it away from the case, reinstalled it and tractored on.

Pat

 

[SPYDERLK]

That's a connection or cable problem, not a battery or starter problem.

What RickB said. You probably have a degraded cable to lug crimp junction. You can turn on lights and use a sensitive VM across each junction to find it. Readings across the good ones will be very near ZERO. With just lights as a load you may see a volt or so on the bad one.
larry

 

[patrick_g]

If you have a helper or a remote starter switch you can measure the voltage between the battery terminals and the attached cable clamps one at a time during brief cranking. The high current will cause there to be several volts lost at a bad connection. Do this with the battery ground connection to the chassis and at the starter terminals as well. If any of these connections are bad they will steal lots of cranking power. Turning on the lights will not help check the starter connections.

Pat

 

[SPYDERLK]

Quote patrick g: Turning on the lights will not help check the starter connections.

This will be true only if it is not a fault in the ground cable and power for the lights does not derive from the + cable at the starter solenoid. Many road vehicles have a separate smaller + lead originating at the batt that feeds all accessories. That arrangement would not load the + cable when the lights were on and you wouldnt be able find a bad joint in the + cable. All of my tractors conduct power to the system thru the + cable and the current servicing the lights passes thru all joints with inherent V drops at each. In such case, a sensitive V meter enables you to establish a figure of merit for each joint in comparison to one another. The 5 or so amps drawn by the lights is plenty to give an indication. Another way would be to draw current to the solenoid - that click you hear - for several seconds and then feel each joint for heat. A bad joint will warm - - or maybe get hot so touch carefully
larry