Problem: New Holland 1720 will not start. The engine turns over. Used jumper cables connected to my truck and it did not help. The indicator for the glow plugs on the instrument panel does not light (light bulb is okay). Disconnected the bus bar to the glow plugs and checked the ohms on each of the three glow plugs (negative lead to battery ground positive lead to top of glow plug). All three checked 5 ohms or less. Where to go from here?
New Holland 1720 will not start
- Thread starter toddt
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Soundguy
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making fuel at injector lines when you turn over?
check the key-off solenoid?
any fuses blown?
gennting good fuel to the pump? ( bleed? )
making any smoke when turning over?
check the key-off solenoid?
any fuses blown?
gennting good fuel to the pump? ( bleed? )
making any smoke when turning over?
Getting white smoke when turning over.
No fuses blown (only found three - two 10 amps and one 15 amp) Don't know of any others.
What is the "key-off solenoid"?
Will check the fuel tomorrow.
Thanks for reply.
No fuses blown (only found three - two 10 amps and one 15 amp) Don't know of any others.
What is the "key-off solenoid"?
Will check the fuel tomorrow.
Thanks for reply.
Soundguy
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key -off solenids are what stop the injector pump from getting fuel when you turn the key off.
back in the old days we had to pull a fuel stop cable to kill a diesel
back in the old days we had to pull a fuel stop cable to kill a diesel
90cummins
Veteran Member
White smoke is an indication it is getting fuel, so the glow plugs must not be working.
Use you volt meter to check for voltage at the glow plugs with the key in the heat position.
No voltage would indicate a bad relay or connection.
You could verify this problem & get it running by jumping the glow plugs to the battery + terminal for 5 seconds or so then crank it to see if it starts.
Don't jump it too long otherwise you will burn the glow plugs out.
90Cummmins
Use you volt meter to check for voltage at the glow plugs with the key in the heat position.
No voltage would indicate a bad relay or connection.
You could verify this problem & get it running by jumping the glow plugs to the battery + terminal for 5 seconds or so then crank it to see if it starts.
Don't jump it too long otherwise you will burn the glow plugs out.
90Cummmins
brin
Super Member
I have a master fuse ( 30 amp) on my TC-29 on the opposite side ( right side facing the tractor ...by the starter ) and the other 3 fuses you mention are in the fuse panel...I don't know if you have a main 30 amp fuse...might want to check unless you know...but Chris...Soundguy will know.
Checked voltage at glow plugs, none there. Removed ignition switch and checked continuity between terminal 30 and 19 when in HEAT position, checked good. Jumped glow plugs as you suggested, she started right up. So, must be the TIMER RELAY. Will order it tomorrow. Thanks for everyone's help, truly appreciated.
Soundguy
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when you get it in, let us know what ya find / how she starts.
Well, not good news. Replaced the glow plug timer ($99) and it was not the problem. Looking at the circuit the only thing I can figure out is a bad ground. Will work on that tomorrow, right now I am commiserating with Old No. 7
Soundguy
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have you bypassed the NSS?
Both the Transmission and PTO NSS switches are good. The PTO switch is a bear to get to.
The glow plug timer relay part number on tractor is SBA385870300 the one that was just purchased is different by one digit: SBA385870301 the parts guy said it was improved version?? Wonder if that makes a difference?
Soundguy
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a relay is basically a switch to actuate large current with small current. if it meets the specs.. I doubt it's a problem. ( IF ).
you see PLENTY of superceeded parts on older machines.
have you checked to see if the new relay IS energizing as it shoud?
you see PLENTY of superceeded parts on older machines.
have you checked to see if the new relay IS energizing as it shoud?
jimmysisson
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I thought I read on here the timer was just for the light, and current to the GPs was controlled by the ign switch. (Maybe that's only on a newer model.) Do you get current to GP bus bar full as long as you hold switch in Heat position?
Probably you need someone better informed than I.
Jim
Probably you need someone better informed than I.
Jim
Have been looking for a diagram of the Timer Relay but have not been able to find one. It is not a real relay therefor I'm unsure of how it works without seeing the diagram (circuit with pin numbers). It is my understanding that it controls how long the voltage is applied to the glow plugs. It is an "NGK lamptimer 12vdc". From all that I have read it appears that most diesels have a timer like this. I'm about to give up and have it trailered into the dealer however, the closest one is 40 miles away and I can still jump from the battery to the glow plugs to get her running. I'll probably keep fooling with it until something lights the dim bulb in my head.
Soundguy
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a test lamp should tell you what pin is going hot (timed) when it is on.. etc.
Success, thanks Soundguy for sticking with me on this problem. Got out my test light and started tracing wires and voltage. Got back to the ignition switch had the voltage on the ignition switch but not at the plug that was 8 inches from the switch. Stripped away the heat shrink and there it was a broken wire. It has been repaired and the tractor is happy.
Soundguy
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don't you love the easter eggs. IE... hidden problems you have to find.
glad you found it!
glad you found it!
I remember "easter egging" from my navy days...
jimmysisson
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Was the "plug" a wire connector in the glow plug circuit? Did you determine the relay times the GPs, not just the light?
Glad you got her fixed.
Jim
Glad you got her fixed.
Jim
Jimmy, the plug is right off of the ignition switch. It has all the wires from the ignition switch going into it and the broken wire was hidden under heat shrink tubing. I had removed the ignition switch and checked continuity right between the posts on the switch. No, did not determine the relay times, I am assuming that it is the same time that the GP light is lit.
