D721 Won't start - Electrical Issue - Revised Question

[Greg1881]

My 1998 D721 with the Kubota Diesel just won't start. When I try to start it the lights go dim, the starter engages, the selenoid pulls the fuel rod back, but it acts like the battery has no power to even try starting the mower. It will barely crank on the first and second try, then by the third time it won't even crank, but the lights still work. I hooked up the 1 year old battery from my F150 and I get the same exact problem. so I know it is not the battery. Has to be an electrical issue, any suggestions what i can check

 

[mechanic mark]

Check all electrical connections especially ground straps & cables by hand making sure they are all tight & secure, try moving by hand if loose then tighten. Also check for corrosion, baking soda & water will remove corrosion.

Replacement Manuals | Grasshopper Mower

http://dealer.grasshoppermower.com/files/electrical_troubleshooting_vol_2_2016_5_0216_l.pdf

 

[Hammermechanicman]

Start with a known good battery. Connect a volt meter to the negative battery post. Not the cable clamp but the actual battery post. Coneect the other lead to engine ground at the starter. Try to start the engine and read the meter. Should read about 1/4 volt ir less. Over half a volt indicates a corroded connection between battery poat and engine ground. Then connect the volt meter between the positive battery post and the other to the large terminal on the starter that is NOT connected to the battery but rather the one closest to the starter body. Try to start the engine. Any reading over 1/2 volt indicates a problem with a corroded connection with the positive cable OR the solenoid contacts of the starter. If the readings are around 1/4 to 1/2 volt when trying to start the engine the high current connections are good.