neutral safety switch on new holland tt75a

   / neutral safety switch on new holland tt75a #1  

lancemo

New member
Joined
Oct 19, 2012
Messages
1
Location
parker pa.
Tractor
new holland tt75a
i have to jump out the neutral safety switch on my nh tt75a to get it to start. i bought a new switch and installed it still nothing. i tried innstalling it with the rearend in neutral, low, and high. nothing. reversed wire polarity, still nothing. if i bypass the switch by connecting the terminals to the switch together it starts. any ideas for me? i bought the tractor new in late 07, and it only has 51 hrs. on it.
 
   / neutral safety switch on new holland tt75a #2  
Check the continuity of your switches with a tester across the posts. There should be continuity across the posts without depressing the button on the switch. Pushing in on the button should break the continuity.
Likewise, you can hook up the switch out of the tractor to the harness. Without doing anything to the switch, turn the key to start and the engine should crank. Push the button on the switch while turning the key to start and it shouldn't crank. MAKE SURE TRANSMISSION IS IN NEUTRAL WHEN DOING THIS!
If your switches are good, then you need to look in the bore where the switch screws in and see if there is a depression that shows up on the shift rail when the shifter is in neutral.
It is very probable that your old switch AND the new switch are bad. Just because it is a new part does not mean it can't be faulty.
 
   / neutral safety switch on new holland tt75a #3  
In general clutch neutral safety is a " normally open" switch by an action of spring that keep the contacts separate. Neutral safety should not have a continuity if the switch is not pressed. Once clutch pedal is pushed by mechanical manipulation the switch should go from open to close hence completing the starter circuit and eventual crank. There might be other safeties in series that could effect starting such as PTO safety and Operator Presence control (seat switch). They all are (N.O) switches. Sitting closes seat switch and "PTO off" closes pto safety.

JC,
 
   / neutral safety switch on new holland tt75a #4  
In general, you are correct. A 'clutch safety switch' is "normally open (N.O.)" and your description of the clutch safety switch operation is excellently detailed.
A 'neutral safety switch', which is usually found on the transmission shift rails, is "normally closed (N.C.). In this case, I believe that the TT75 utilizes a safety switch on the transmission, rather than on the clutch. While it is true that the PTO safety system could be a culprit, I do not believe that the 'fanny switch'/OPS/seat switch is causing the problem since bypassing the neutral safety switch eliminated the problem, temporarily, then returned when it was connected back normally.
 
 
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