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I have an old riding mower that will not start. The first thing I checked was the continuity on the positive battery cable and the needle barely moves. So I think I need to replace the positive battery cable but I wanted to check that I am on the right track. If so parts of the cable are contained within a larger wiring harness that is difficult to access. Can I just add a new battery cable along side the harness or do I need to remove the existing one and enclose the new on in the harness.

DadTo10 said:

I have an old riding mower that will not start. The first thing I checked was the continuity on the positive battery cable and the needle barely moves. So I think I need to replace the positive battery cable but I wanted to check that I am on the right track. If so parts of the cable are contained within a larger wiring harness that is difficult to access. Can I just add a new battery cable along side the harness or do I need to remove the existing one and enclose the new on in the harness.

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Take the battery and get it checked at an auto store

Check at connections

Try and jump start with a known good battery

Most likely a bad battery

Dad to 10 when you checked for continuity what setting was your meter on ???? If it was on high ohms it will barely move...

The cable ends are what go bad and corrode.......... Yes you can leave the old cable on and just run a new one..... Cable tied to the existing harnes.........

Depending upon how old the mower is and who made it neither ow which you chose to divulge which makes giving you any meaningful help difficult, the cable could be 27 strands of heavy wire ( cheap ) or 200 strands of hair wire ( expensive )
The former rarely gives any problems except at the terminals while the latter can corrode internally.
So put one terminal in a vice then put a bolt through the other end and give the wire a good jerk .
If the terminals stay on and the cable does not break then chances are it is good.
Here is a proceedure that will verify the cables & connections

Before you start, pull the spark plug & try to rotate the engine by hand.
No use checking the electrics if you have a hydraulic lock, seized engine or jambed belt overloading the stater motor.
Assuming the engine turns freely.

I like to start from the starter motor and go backwards .
Do the following 5 tests, regardless of the results from an or all of them as there can be more than one problem and you want to isolate where the problem lies.
Elimination of individual parts is important so you know by the end, the battery, solenoid & heavy power circuits are all in good order.

1) try to jump the starter motor directly from your car or truck.
Starter turns = starter good

2) do the same directly from the mowers battery
Starter turns = mower battery good
No turn = duff battery, recharge it & try again.

3) check for voltage ( + 12V ) at the solenoid trigger wire with the key in start position
3a) same with ground trigger wire ( 4 wire solenoid ) or body of solenoid ( 3 wire solenoid)
( I like to test V from the battery hot terminal to ground terminal rather than ohms as they give funny readings )

4) leave ground jumper in place ( from step 2 ) & try key start.
Starter turns = power connection good but ground connection suspect ( most common )
Confirm it by trying again, extra ground removed
I run a secondary ground from the grounding bolt to one of the starter mounting bolts & paint over both with liquid electrical tape.

5) Remove the trigger ( thin ) wire / wires from the solenoid.
Ground one & bridge from the hot terminal to the other.
Starter cranks = solenoid good.
Solenoid is not polarity sensitive, BUT THE WIRING IS so make sure you remove the thin control wires.
Note a thinner wire on the hot terminal is not a control wire. It is the main power feed to the mower.


From here on things become very mower dependant as starting circuits are getting changed all the time.
Basically the power goes in a loop from the hot side of the solenoid ( saves wire, no other reason ) through the fuse to the B terminal on the key switch then to the PTO switch then to the parking brake switch then to the solenoid trigger switch , easy peasy after you grow the 3rd arm. Use a test lamp and follow the power.
However a lot of mowers with a 4 pole solenoid, run a secondary ground control circuit to the ground solenoid wire through the lap bars.
Then to stop this interfearing with the normal safety function of the ground kill, it goes to a relay with the ground as the switched connection.
These are a PIA as the + control wire to the relay comes from the power loop above and the ground side of the control comes via the normal cut out functions of the lap bars.
Be very careful because if you have a system like this and accidentally send 12V down the ground loop you can fry the magnetos on some circuits.

Thanks for the replies let me try to catch up. It is a 2009 MTD 42 inch riding mower. And you are right about the battery cable it looks in good shape with no voltage drop and no corrosion.

• The battery is good, reads just over 12 volts
• Key in start does nothing
• Jumping positive to starter turns the starter

So if I understand my next step is to check the voltage at the solenoid.

DadTo10 said:

Thanks for the replies let me try to catch up. It is a 2009 MTD 42 inch riding mower. And you are right about the battery cable it looks in good shape with no voltage drop and no corrosion.

• The battery is good, reads just over 12 volts
• Key in start does nothing
• Jumping positive to starter turns the starter

So if I understand my next step is to check the voltage at the solenoid.

Click to expand...

You do understand a battery can be bad and still show 12v ?
Read the voltage when someone tries to start the mower.
They can have a bad cell.
have you tried jump starting it?

DadTo10 said:

Thanks for the replies let me try to catch up. It is a 2009 MTD 42 inch riding mower. And you are right about the battery cable it looks in good shape with no voltage drop and no corrosion.

• The battery is good, reads just over 12 volts
• Key in start does nothing
• Jumping positive to starter turns the starter

So if I understand my next step is to check the voltage at the solenoid.

Click to expand...

Yes check the trigger wire on the solenoid for 12V when you turn the key.
If no volts, try jumping from the hot terminal to the trigger terminal as per the isntructions to work out if th wiring is bad or the solenoid s bad.

Thanks for the help again. I couldn't get to it for weeks due to rain. Here is the strange part. I figured I would try starting it one more time before getting into the troubleshooting and it started right up. I have no clue why. I had tried many times to start it before the rains came and it would start but now it's fine. Many thanks again, however for your help and advice.

Likely your problem will recur. Sounds like a loose connection or corrosion.

Good point. I will keep that in mind. Thanks for the help