B7100 glow plug indicator not glowing.

Little tractor20

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B7100d
Sep 21, 2020
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1
Ohio
Whats up everyone. I have an old b7100. Glow plug indicator does not glow. I know the glow plugs are working because tractor will not start cold unless I cycle the glow plugs. I think it might the filament might be smoked. Any ideas would be appreciated.
 

85Hokie

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BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Jul 13, 2013
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Bedford - VA
Whats up everyone. I have an old b7100. Glow plug indicator does not glow. I know the glow plugs are working because tractor will not start cold unless I cycle the glow plugs. I think it might the filament might be smoked. Any ideas would be appreciated.

Take it out - or unhook one lead off the back - set your ohm meter to continuity and see if it reads ZERO ohms or something real close to zero - or if you have an audible meter - see if it beeps.

I have only seen mine glow once - and that was I wanted to see it glow - had to hold the switch for at least 45 seconds to see it in dim light.

they are about 40 bucks to replace!
 

Roadworthy

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L2501 HST
Aug 17, 2019
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If your "indicator" is a coil of nichrome wire like many older tractors you may NOT see it glow. If it burns out or opens in any way though your glow plugs won't work at all. They're wired in series with it. Glow plugs run at 10.5 volts. That coil of wire drops the extra 1.5 volts.
 

Lil Foot

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1979 B7100DT Gear, Nissan Hanix N150-2 Excavator
May 19, 2011
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I thought mine was not glowing early on. Turns out, they get crusty with corrosion & dirt. I cleaned mine with a fiberglass pencil, and it glows just fine. Now, after a few years, I can only see it in low light (dark) conditions.
For those who have never seen the fiberglass pencil, (cleaning brush) they can be had in various sizes:
 

Dave_eng

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M7040, Nuffield 465
Oct 6, 2012
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If your "indicator" is a coil of nichrome wire like many older tractors you may NOT see it glow. If it burns out or opens in any way though your glow plugs won't work at all. They're wired in series with it. Glow plugs run at 10.5 volts. That coil of wire drops the extra 1.5 volts.
With the Key in the start position, the glow indicator is bypassed and the GP's receive power.

This feature an cause confusion when troubleshooting the GP's

Study the two schematics and you will see how the GP indicator is bypassed in the Key start position.

In pre heat the power flows from Terminal #30 to terminal #19, then throught the GP indicator and finally out to the GP's via terminal #17.

In the Start position power flows from terminal #30 to terminal #17 (bypassing the Indicator) and out to the GP's.

forum B7100 GP 1.jpg

forum B7100 gp 2.jpg


Dave