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Craftsman 917-27106??

5111 Views 32 Replies 4 Participants Last post by  Bill Kapaun
I have a 90's craftsman lawn tractor with a 15.5 Kohler ohv motor. Has been running fine until a few moments ago. Now it blows the 20amp blade fuse after running for a few minutes. Any thoughts on where i should be looking. If there was some sort of short, wouldn't the fuse blow immediately? Thanks for the help.:
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Can't you read the last digit of the Sears 917? or ??
That series includes 271060 through 271065. (at least)
Amongst those, there are 4 different schematics.

Give me a few minutes to look at all of them to see how similar they are.

Can you find the last digit?
If not, let me know if it has Operator Presence Relays.
It's hard to help someone that won't respond!
If you have 917-27106, only the last digit is missing.
As i mentioned, there are 4 different schematics for the 6 (all hydro) numbers I mentioned.
Determining which one can save a lot of needless guessing. Some have OPR's & some don't. That's a potential trouble spot. IF we can eliminate an OPR, it greatly simplifies things.
There are a couple things to do to narrow down your specific tractor.
271060 CV15S-41567
271061 CV15.5S-41596
271062 CV15S-41592
271063 CV15.5S-41596
271064 CV15-41598
271065 CV15.5S-41596
Look at the engine # and see if any match yours.
It "appears" we can eliminate 3 right off the bat.
Does it have OPR's? If you don't know, that's OK. We can do a simple test to try to determine that.

It doesn't appear models 271066-69 exist.
I just need feedback.

EDIT- quick test-
Do the headlights work? IF not, that "points" to a shorted stator and likely a shorted charge diode.
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Just noticed that 271061, 271063 and 271065 all use the same CV15.5S-41596
engine. Is there something else that sets them appart?
Number of OPR's.
3, 0 & 2

I'm not going to compare other parts, since this thread is about an electrical issue. It's a pain just to have 6 pdf's opened up to compare schematics.
we got it narrowed down then- 917.271062
Here's a link to the manual-

OPR is an Operator Presence Relay.

Look at the schematic on page 31.

What I'd like you to do is disconnect OPR#3.
That will isolate the alternator from the charging circuit.
IF you can't determine #3, (should have a RED wire to pin 87) than unplug all 3 of them.

You'll need to get it started-
Check if head lights work. (That means alternator might be OK) 1/2 the alternator provided current for them and 1/2 for battery charging.

To find them (you'll need a fuse)-
With key ON, manipulate the seat switch.
They should click. Fuel solenoid should also click.

Do you have an OHM meter?
IF so, check the resistance between pins 85 & 86 of the relays. Should be about 65-70ish OHMs.
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What OHMS scale were you on?
IF a very high scale, 70 would look like a near short. (your result)
If say a 200 ohms scale, it should read more in the middle of the scale.

You could compare to the other 2 OPR's. They should all have similar readings. IF 1 seems out of wack to the other 2, you likely have at least 1 bad one.

The fact the headlights worked is a good sign.
It doesn't prove the charging side of the alternator is good, but I haven't heard a case of just 1/2 the alternator going bad.

Look at your schematic and note the diode that comes off the alternator.
A diode acts as a check valve.
On the alternator side, you have AC volts input to the diode.
The diode only allows the positive pulse through and "blocks" the negative pulse. (sine wave)
Thus, you get a pulsating DC for charging the battery. (lights are AC, since they don't care)

Locate the diode-
Using the various OHM ranges on your meter, test the diode.
Hook the leads in one orientation and then try the other way.
IF the diode is good, you should find at least one scale on the OHM meter where the diode conducts in one direction (meter deflection) and NOT the other.

IF you have a 12V test light, there are some other tests we can try.
Substitute the test light for the fuse.
It should light up to some extent.
Observe the brightness when trying only ONE OPR plugged in at a time.
If ONE of them is noticeably brighter than the others, it's "suspect".

A readable meter would really be handy-
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My wild guess would be that your electric clutch has a short.
Some times you can fix this with liquid electrical tape.
You'd have to install an electric clutch first.
I took the flywheel cover off. No diode that i can see. Only the coil sits next to the flywheel.
The coil will have the kill wire attached to it. Ignore this-
There should be 2 wires coming off the stator- (Yellow?)
One connects to an orange wire that goes to the key switch. That's the AC lighting circuit.
The OTHER one should have the diode between where it leaves the stator and pin 30 of OPR3.
Yellow? TO the diode and Red? from the diode to OPR3.
(sometimes the actual wire colors deviate from that shown on the schematic)
The diode may simply appear to be a "lump" in the wire covered with heat shrink tubing.

This engine has an "alternator brake" which has extra wires going to the stator, confusing things. This is the wiring associated with OPR2

Did you try my other tests with a 12V test light?
For the test light checks, leave the engine OFF.
Just the key ON.
You can have the key OFF while you swap OPR's around.
Look for one or more that lights up noticeably brighter than the others.
All 3 installed should be brightest.
Removing any one should reduce brightness.
Removing any two should reduce brightness more.
All 3 should reduce brightness the most.
The fuel solenoid should draw a similar amount of current.
With the fuel solenoid and all 3 OPR's disconnected, the light should be out, since no current should be flowing.
Remember, you have to "manipulate" the seat switch (occupied) to "turn them ON".
Look at the schematic.
Current flows from A1 on the key switch, through the seat switch to the OPR's.
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I'm 60 miles East in Albany.

Forgot on the diode-
The circuit has to be disconnected so that you are only testing the diode.
IF you disconnect OPR 2 & 3, you can insert the test leads into pin 30's of the OPR PLUGS.

Currently 54 in Newport
Your meter should have an AMPS range.
That would be a better test.
Use the highest range you have, assuming it's at least 2 amps.
Repeat the test, adding one load at a time. (be ready to disconnect quickly if you go over range!!!!)

My gut feeling is that the relays are OK.
More likely, you have a wire where the insulation has rubbed off and intermittently is shorting. (pretty much anything that connects to A1 of the key switch)

Another possibility is a defective key switch that is shorting internally.
Not really a positive test, but you could remove the switch-
Hook OHM meter to A1 & G terminals.
In the ON position, wiggle the key, tap the body etc. and see if you show "flashes" of continuity. IF you do, that's a short.
"Hook OHM meter to A1 & G terminals.
In the ON position, wiggle the key, tap the body etc. and see if you show "flashes" of continuity. IF you do, that's a short"

It will show continuity in the OFF position.
Any other position, it should be open.

Look at the little chart (truth table) on the lower left of the schematic.
It should only do what the chart shows.
If the starter or solenoid had an internal short, it'd only blow the fuse when they were in use. (when starting)

Look for a bare spot in a "hot" wire.
It would likely be in a spot that was vibrating against metal and wore through the insulation.
You could try running it with the OPR's removed to see if it's in one of those 3 circuits.
When OPR 3 is removed, you won't have battery charging.
OPR 2 activates the flywheel brake. (I would consider it the most suspect)
I answered that question in post #30.

Since were going to go into hit or miss mode-------
With all the OPR's removed-
Disconnect carb solenoid wire.
Turn key on and wait. See if fuse blows.
If not, hook up carb solenoid and repeat.
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