Glow Plugs B7100

[TxRzrBk]

On an old B7100 - key turns left to send power to the glow plugs

I recently replaced some wiring from my ignition switch to headlights, horn and glow plugs, previous owner had done some shody wiring modifications for reasons unknown. I noticed after replacing the wiring that my battery is completely dead after running the tractor for anything above a couple of minutes. Upon further investigation I found that the glow plugs are getting power while the key is in the on position. I checked the power on the back of the ignition switch assuming that I had done something wrong. After checking each terminal on the ignition switch I do not have a terminal that is powered when the key is turned counterclockwise (preheat position) but NOT powered while the key is on. I am assuming this is not correct but wanted to double check before I replace the ignition switch.

EDIT

Looking at the wiring diagram I am confused by the wiring of the glow plug indicator in relation to the glow plugs. Can someone explain?

 

[North Idaho Wolfman]

My B7100 isn't here with me, but I think when I checked min it had power in both positions, Pre heat and run, maybe someone else that has their tractor with them could test it.

When the switch is in preheat, power goes from the switch #19 through the indicator back to the common connection on terminal #17 then out to the glow plugs.
Then in run it feeds the glow plugs out of 17 thus bypassing the indicator.

 

[kubotasam]

Power needs to get to the glow-plugs at 2 different positions on the switch.
1--- preheat position---power comes from the switch through the indicator coil (which is actually a resistor to drop the voltage form 12 to around 9) then to the glow plugs.

2.--start/crank-- power comes from the switch, bypasses the indicator/resistor and goes directly to the glow pugs. The voltage drop from cranking the starter drops the available voltage to the glow plugs to around 9.

You do not want voltage to the glow plugs in the run position. They would be powered all the time and would burn out in a short time.

 

[lsmurphy]

Power needs to get to the glow-plugs at 2 different positions on the switch.
1--- preheat position---power comes from the switch through the indicator coil (which is actually a resistor to drop the voltage form 12 to around 9) then to the glow plugs.

2.--start/crank-- power comes from the switch, bypasses the indicator/resistor and goes directly to the glow pugs. The voltage drop from cranking the starter drops the available voltage to the glow plugs to around 9.

You do not want voltage to the glow plugs in the run position. They would be powered all the time and would burn out in a short time.

This..............................

 

[TxRzrBk]

Thanks for the responses

Ok so there is no way my ignition switch can support what you have described, to meet those requirements it would need to have a terminal that would be ON in preheat position but OFF in the key on position.

 

[lsmurphy]

Correct, a new ignition switch can be bought on ebay for about $30.

 

[olthumpa]

I recently replaced some wiring from my ignition switch to headlights, horn and glow plugs,

By chance did you reverse the wires going to the headlights and horn from the switch with the wire going to the glow plugs? If you did this the glow plugs would always be on.

Just a thought.

 

[lsmurphy]

On an old B7100 - key turns left to send power to the glow plugs

I recently replaced some wiring from my ignition switch to headlights, horn and glow plugs, previous owner had done some shody wiring modifications for reasons unknown. I noticed after replacing the wiring that my battery is completely dead after running the tractor for anything above a couple of minutes. Upon further investigation I found that the glow plugs are getting power while the key is in the on position. I checked the power on the back of the ignition switch assuming that I had done something wrong. After checking each terminal on the ignition switch I do not have a terminal that is powered when the key is turned counterclockwise (preheat position) but NOT powered while the key is on. I am assuming this is not correct but wanted to double check before I replace the ignition switch.

EDIT

Looking at the wiring diagram I am confused by the wiring of the glow plug indicator in relation to the glow plugs. Can someone explain?

First off, your diagram is NOT for a 7100........it is for a 4 cyl......so I would not rely on that for the 2 position switch.



Do you have a test light?

If you wired your switch according to the diagram you are using you may very well have wired your GPs to a wrong post on the switch.




I would help you with this but I'm not going to take my dash off........I have already wired my own some time back and I remember only one post will feed the GPs.


You are saying that if you tested right now......you do not have a post that feeds only in the preheat position? When you turn to start that post remains hot???? If so, you are likely backfeeding it from the second post which does heat in the start position.

You follow that?

 

[TxRzrBk]

Just read your post after I figured it out. It occurred to me that there wasn't any sure way to check the ignition switch without disconnecting all of the wires. I labeled everything and pulled the switch and it tested fine.

I guess the previous owner was a nut case, wires had just been randomly moved from one terminal to another. The only thing I changed in the wiring was removing a length of extension cord that was being used in place of the original glow plug wire...yes extension cord.

It seems to be working correctly now but the way I connected everything was based on the diagram I attached to my original post. Does anyone have the correct diagram or can you tell me what is different, other than the 4 cylinders in the picture?

 

[Lil Foot]

Hope you can see enough detail:

 

[lsmurphy]

 

[lsmurphy]

email me at jeepmurphy@gmail and I will email you the manual and parts illustrations.

I have another one to send tonight after midnight..........I'll send yours as well.

 

[TxRzrBk]

Cant see much, lots more detail but as far as the ignition switch is concerned it looks to be identical.

 

[Dan_R_42]

The B7100 key switch has 5 screw positions. They are marked on the back of the switch - 19, 17, 50, 30, AC

19: is the Glow Plug - Pre Heat lamp position

17: is the terminal that the glow plugs are tied to.

50: Start Position - Starter Solenoid (via the clutch safety)

30: is the Always "HOT" terminal, to + battery cable on starter

AC: ON key switch position, & headlight sw, oil light

 

[TxRzrBk]

That is how mine is connected. The nut case who the tractor before me had moved the connector w/ glow plugs + preheat indicator (should be on 17) to AC and moved the starter solenoid to 17. It still started and ran but the glow plugs were shot and had to be replaced and although it had a newish battery he told me it was no good. So the glow plugs were thrashed by being on anytime the key was ON and the battery wouldn't stay charged because the glow plugs were powered anytime it was running.

Problem solved - thanks to all for the help