B series electrical question

[vtmbz]

Bought used b5100 tractor with burnt out electric clutch coil.
Replaced the coil with help from Kahuna on parts numbers and now it mows great. Thanks for that! It saved me 250.00 to know the clutch coil part #.

SO now Im wondering: What burns out an electric coil in the first place, and can it be fused to prevent this in the future? If so, what fuse would be the right size?

Also, the primary (red) wire to the starter shows melting, and a lot of soldered repairs-- what happened there? Is this a related problem to my burnt out coil
or did somebody just crank the poor thing to death one day? It doesnt crank well but I havent load tested the battery yet, or the starter.

There also appears to be a short since 11 volts flow through the battery cables with the key off. Voltage regulator?

I add all this because it seems to me this all might be related to the same event. Am I on the right track?

 

[Bulldog]

That's a lot of questions so I'll pick one and start there. You said you haven't load tested the battery yet. Where does it have 11 volts at?

 

[lsmurphy]

Make yourself up a new wire harness. Easy to do and cheap.

Solder your lugs on your new batter cables.

Move your ground from the steering box to stud just above the starter or to the starter. Add a ground to the dash.


Poor grounds are the primary reason for electrical failures.

 

[vtmbz]

That's a lot of questions so I'll pick one and start there. You said you haven't load tested the battery yet. Where does it have 11 volts at?

With battery installed I test 12.5 volts across the terminals. If I switch off the key, disconnect the negative cable and use the volt meter to complete the circuit, I read ll volts. The alternator when running charges at 14.5 volts.

I will reroute the ground as suggested. Would bad ground kill the clutch coil?

 

[Big Kahuna]

Yes, all my pto clutches are fused with a 10 amp fuse and I have never had a problem. and make sure all your fuses are good because they will cause problems.


Big Kahuna

I'm glad I could help you.

 

[lsmurphy]

 

[vtmbz]

IsMurphy: Thanks for the detail. Ive put the tractor up for the winter. It seems to need a complete wiring inspection at the least. Im still curious about how to test my voltage regulator for a blown capacitor.

 

[Bulldog]

With battery installed I test 12.5 volts across the terminals. If I switch off the key, disconnect the negative cable and use the volt meter to complete the circuit, I read ll volts. The alternator when running charges at 14.5 volts.

I will reroute the ground as suggested. Would bad ground kill the clutch coil?

If it reads 12.5 across the battery it should read the same with the ground cable off. Maybe you didn't have a good ground with your meter lead.

 

[vtmbz]

Bulldog: Im using the volt meter to complete the circuit to ground. WIth the key off, I get a discharge of 11 volts. It seems to me I ought to get nothing flowing to ground with the key off, indicating a short. True?

 

[asbug]

ISMURPHY,
What did you use to fix those lights?
Is it a fog light kit?
I have a B7100 and the hood set up is the same.
Thanks.
KC

 

[lsmurphy]

ISMURPHY,
What did you use to fix those lights?
Is it a fog light kit?
I have a B7100 and the hood set up is the same.
Thanks.
KC

4" driving lights can be found at OReilly for $25

Rubber gaskets are for the 4" tail lights for a trailer, Grote, found at NAPA for $2 each. Cut to make a ring that cusion the glass agaist the metal of the hood.

Retainers are cut from fender washers. Use existing bolt holes.

 

[asbug]

Nice!
That is what I have been wanting to do since my bulb holders are toast.
KC

 

[Bulldog]

Does it read 11 volts with the neg cable hooked up. I don't see why it would change if you unhook the cable.

 

[vtmbz]

Bulldog: I cant draw with this computer but Ill try to explain what Im doing.

A digital volt meter with the positive probe on the the positive terminal of the bat and the negative probe on the neg terminal of the bat gives me a reading of 12.5 volts. Low but not fatally so.

Now I unhook the ground cable from the battery. I then put the positive probeof my volt meter on the neg terminal of the battery. I put the neg probe on the ground cable. With the key off, I get a reading of 11 volts to ground. It must indicate a short?

I said earlier that I suspected a capacitor in the voltage regulator, I meant to say diode, its just that Im not the electrical sort. Im fairly sure you shouldnt get a reading at all with the key off; otherwise every battery in the world would run down. Since I get 14.5 volts with the engine running, the alternator must be doing something right, so that leads me to the VR.

I know I have some basic testing to do-- that has to wait a bit. I really would like to know how to test a VR.

 

[lsmurphy]

Bulldog: I cant draw with this computer but Ill try to explain what Im doing.

A digital volt meter with the positive probe on the the positive terminal of the bat and the negative probe on the neg terminal of the bat gives me a reading of 12.5 volts. Low but not fatally so.

Now I unhook the ground cable from the battery. I then put the positive probeof my volt meter on the neg terminal of the battery. I put the neg probe on the ground cable. With the key off, I get a reading of 11 volts to ground. It must indicate a short?

I said earlier that I suspected a capacitor in the voltage regulator, I meant to say diode, its just that Im not the electrical sort. Im fairly sure you shouldnt get a reading at all with the key off; otherwise every battery in the world would run down. Since I get 14.5 volts with the engine running, the alternator must be doing something right, so that leads me to the VR.

I know I have some basic testing to do-- that has to wait a bit. I really would like to know how to test a VR.

Your short could be anywhere along the way too.

Go through all your wiring...........could even be a bad ignition switch.

 

[moog]

Bulldog: Im using the volt meter to complete the circuit to ground. WIth the key off, I get a discharge of 11 volts. It seems to me I ought to get nothing flowing to ground with the key off, indicating a short. True?

With your meter in series and set to volts you are measuring the potential voltage difference between the two points. You are not measuring any "flow" or work, just voltage potential. With the ground wire unhooked and the meter wired between you will always have a potential difference, short or no short. The only time you would ever read 0 volts at those two points is if the battery is completely and absolutely dead. You would have to have a meter that reads DC amps to find out if any "flow" or work was going on with the key off.

*edit*Or you could read 0 volts at the point you are measuring if the battery was bad ie the connection between the battery negative post and the battery plates was open etc.

 

[lsmurphy]

With your meter in series and set to volts you are measuring the potential voltage difference between the two points. You are not measuring any "flow" or work, just voltage potential. With the ground wire unhooked and the meter wired between you will always have a potential difference, short or no short. The only time you would ever read 0 volts at those two points is if the battery is completely and absolutely dead. You would have to have a meter that reads DC amps to find out if any "flow" or work was going on with the key off.

*edit*Or you could read 0 volts at the point you are measuring if the battery was bad ie the connection between the battery negative post and the battery plates was open etc.

If I understand him correctly he is getting a postive reading measuring a ground and the negitive post of the battery while the neg is disconnected. He has a positive short or discharge to ground.

 

[vtmbz]

With your meter in series and set to volts you are measuring the potential voltage difference between the two points. You are not measuring any "flow" or work, just voltage potential. With the ground wire unhooked and the meter wired between you will always have a potential difference, short or no short. The only time you would ever read 0 volts at those two points is if the battery is completely and absolutely dead. You would have to have a meter that reads DC amps to find out if any "flow" or work was going on with the key off.

*edit*Or you could read 0 volts at the point you are measuring if the battery was bad ie the connection between the battery negative post and the battery plates was open etc.

I did not know this. Thats what asking questions is all about...

I started dismantling the harness today looking for a short. If I find anything interesting, I will report back. I also had the battery load tested-- it indicated 130 ah, or about half of its original cca. So I bought a new battery. I am replacing the red primary to the starter since it showed signs of melting and was soldered together in two places. I also found a good place to attach a ground on the block near the starter.

Why is it that the two wires coming from the alternator (I have the old style fan/alternator unit) are both the same color? I would have thought polarity would be real important here....

 

[Stubbyie]

If you disconnect the negative battery terminal and hold it aside and then place probes of a DMM between the now loose negative cable and the negative terminal and you read voltage you PROBABLY have a short in the harness.

That said, sometimes a digital multimeter is ""too"" sensitive and picks up odd stray currents---you could even be reading (depending on meter) microvolts or millivolts from flourescent overhead or worklights or from adjacent wire.

Get an analog (even a cheap one) meter and watch for needle swing. Or use a 12-vdc test light (two wires soldered to a bulb or a salvaged bulb socket).

There are some things a good analog meter can do that DMMs can't.

With a clamp-type ammeter you can rehook the neg cable and try getting a not-in-circuit current reading.

Can do same with either DMM or analog by leaving cable unhooked and using the meter probes to complete the circuit as discussed top of this post.

CAUTION if it is drawing much you could kill the meter---check your meter settings and start as high as possible reading milliamps or amps. Don't do this during starting---you'll melt probe wires and slag meter. Completely safe process to check current, just keep in mind meter limitations for high current flows.

 

[vtmbz]

Removed starter and fuel tank today. Opened up main harness to starter and glow plug circuit. No bare wires but all are brittle and crumbly.

Im sending the starter out for load testing. Maybe a quick rebuild since its already out. I dont think its ever been off the machine.

Tried to pull the steering wheel but no luck so far. I wanted to get at the wiring under the dash panel.

Discovered that the oil pressure warning light is long gone! I have a spare gauge, so I will install that. You have to wonder what people were thinking.