Lt 1500 electrical problems

[jgiljr]

I am trying to figure this out and it has me going nuts. I am not the greatest with electrical. The problem is the tractor will not try to turn over at all. I checked the ignition switch and that reads fine. I tested the solenoid, which reads fine. What was bothering me and had me tracing all the wires is, I was getting continuity on both sides of the headlight wires. I figured there were burnt or chewed up wires and nothing I can see. So I checked the starter I get continuity from hot to negative. I do not believe I should be getting that. The starter seems fine and the tractor starts right up if I jump right to the starter. Shouldn't the starter short out if I have continuity from the ground to hot??? I should mention I also get continuity on the starter with the positive wire disconnected from the starter.

 

[bertsmobile1]

LT 1500 means nothing to a technican .
Your mower could have been made by Murray, MTD, Husqvarna if recient and a dozen others if it is a bit older.
We need the numbers off the sticker under the seat to give you detailed instructions

You tested all these things ,,,,HOW ?
If the starter motor has voltage all the time , it will turn all the time .
When did this start to happen & want was the last thing that happened before the poltergeist took over your mower ?
for a circuit to work it has o start from one side of the power source ( battery or alternator ) and go through to the other side.
SO you can put a switch between the + and the item or between the - and the item , the results are the same , but taking voltage readings can be confusing if ground switching is used and mowers use a lot of ground switching.

 

[jgiljr]

LT 1500 means nothing to a technican .
Your mower could have been made by Murray, MTD, Husqvarna if recient and a dozen others if it is a bit older.
We need the numbers off the sticker under the seat to give you detailed instructions

You tested all these things ,,,,HOW ?
If the starter motor has voltage all the time, it will turn all the time.
When did this start to happen & want was the last thing that happened before the poltergeist took over your mower ?
for a circuit to work it has o start from one side of the power source ( battery or alternator ) and go through to the other side.
SO you can put a switch between the + and the item or between the - and the item , the results are the same , but taking voltage readings can be confusing if ground switching is used and mowers use a lot of ground switching.

The mower started to get finicky it would start one time and not the next. Now no start at all. It has a 17.5 HP Briggs. I will get back tomorrow with the exact model numbers.
I tested the solenoid on the bench with a 12v power supply and tested for continuity with power supplied. That shows fine. My main problem as I can see it is the starter shows continuity from the power terminal to the ground with no wires attached. I don't think it should show continuity like that. I would say a bad starter. But what I see as crazy is the starter works fine if I jump right to the starter. If I disconnect the starter wires the headlights lose the continuity from each lead as if normal.

 

[bertsmobile1]

Thgere are 2 sets of safety circuits on most ride ons .
One prevents the engine from cranking unless the brake is on & the PTO is off .
This bit is common to allof them. After that some also require the transmission to be in the neutral position & / or the driver to be in the seat .
No matter which one you have, they will all prevent the solenoid from activating sending power to the starter.
If the solenoid has only 1 trigger wire then they will all be + 12 V .
If the solenoid has 2 trigger wires that can be either + or -
So the cranking circuit test is to check for battery voltage at the solenoid trigger wire ( and ground on the other if fitted ) with the key in the start position.
The solenoid test is to bridge the battery cable to the trigger wire, engine should crank if the solenoid is a single trigger type .
Unforunaely there is no universal colour standard so the trigger wires can be any colour but mostly they are Yellow, Pink or Orange .
The safety switches are all primaive sliding contact switches controlled by a spring loaded plunger .
Contact is made or lost when the plunger is depressed between the pairs of terminals that have their flat side facing each other .
The cranking circuit is a daisy chain so the power from the key switch mass pass through each & every switch to get to the solenoid & trigger the starter motor when the plunger is depressed.

When fault tracing this circuit I pull all of the plugs one at a time and bridge the terminals in the socket starting with the key switch.
On the back of the switch will be tiny letters and you are bridging the battery B to the Solenoid S .
You then carry on till the starter cranks at which time you have found the problem
Murray in particular uses a clipped in switch and these are prone to wear & twisting so the plunger never get far enough in to make contact.

The other circuit is the ignition circuit and it is a GROUND circuit so all of the safety switches need to be open when the plunger is down or the magneto is grounded and won't spark.

As for the starter motor showing voltage to ground with no wires connected.
That is exactly the reason why I use test lights and not multimeters and in particular not auto-rangeing multi meters.
It is reading the resistance of the armature and probably throwing up a milli volt reading

 

[StarTech]

The craftsman LT1500 is if remember correctly a MTD mower. Still need the model from the serial number tag to be sure. IF it is a MTD an electrical would need to requested from MTD their IPL and OM manuals don't have it included. A real pain as I have to wait several days for MTD to respond to emails.

As for the starter having very low resistance of it has as it pulls at least 60 amps when operating which makes the resistance around 0.2 ohms. The light circuit is most likely an AC driven version which means it is powered by the engine's stator and is wired directly which has also very low resistance.

 

[Cusser]

The problem is the tractor will not try to turn over at all.

A bottle of wine oftentimes gets Mrs. Cusser to turn over !!!!

 

[jgiljr]

I found the problem. The power wire going to the starter was broken inline.
The brake safety switch, although works, the metal tab from the foot pedal was not compressing it all the way.
It turns over now to go over the rest of it. Thank you all for your help!

 

[bertsmobile1]

Excellent
While worn switches should be replaced, you can put a small self tapper into the end of the plunger to make it depress that little bit more.

 

[jgiljr]

Excellent
While worn switches should be replaced, you can put a small self tapper into the end of the plunger to make it depress that little bit more.

Exactly what I did lol