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ihrondiesel

7130 no speed or gear readout

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I have a 7130 with no speed or gear readout. I swapped out the instrument cluster with my 7240, and it works in that tractor. I unhooked the speed sensor from the trans and took it out. Ohms out around 3350. Upon the advice of a local mechanic, I put it in a vise and spun a bolt in a drill by it, the ohms go up & down when I do that. Should I be able to find any voltage at the tractor end of the plug-in with the key on?  I have none there now. 

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If memory serves the ohm range sounds in the ballpark. Sounds like a broken wire or pin in the harness. Ive had a few do that over the years. If it cant see the ground speed the cluster cant decide what gear its in.

 

 

 

 

 

 

 

 

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1 hour ago, 756puller said:

If it cant see the ground speed the cluster cant decide what gear its in.

It does not use speed to determine what gear it is in. 

I anything, if it doesn't know it is in gear, it isn't looking for speed.

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It does use a combination of transmission and engine speed signal to determine what gear its in

 

 

 

 

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13 hours ago, 756puller said:

If memory serves the ohm range sounds in the ballpark. Sounds like a broken wire or pin in the harness. Ive had a few do that over the years. If it cant see the ground speed the cluster cant decide what gear its in.

 

 

 

 

 

 

 

 

That’s what I’m thinking too. The harness looks good but when I unplug the ground speed sensor I have no power there, according to the dealer it should be 4 volts AC. If I unplug the bulkhead connector under the cab and go from there to the GSS plug-in with my ohm meter I can’t pick up anything either. 

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2 hours ago, 756puller said:

It does use a combination of transmission and engine speed signal to determine what gear its in

 

 

 

 

No it does not.  Step on the clutch and put it in gear.  Watch it change as you go through them. No matter what the engine RPM. 

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The Magnums don’t show the gear unless moving. I had one that sometimes would show in reverse 4 when I was in 10 forward.

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Do a history on here. SD man and the other regular CIH techs have explained the magnum gear indicator before.

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I   don't remember if you have to be moving  or not.  I think  I will get out my operators manual and maybe even the service manual and see what it says. 

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Right out of a Magnum service training manual. Pretty self explanatory. 

407919F4-02B5-45DC-8EDF-A573B0B7A9AF.jpeg

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I stand corrected.

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If you have any way to pierce the wire a ways back from the pins id check for continuity between there and the pins. They usually like to break in that area

 

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Is there a picture of the bulkhead connector in a dealer knowledge article or similar publication that will tell me which pins I need to be checking?

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This topic reminds of an incident that occurred 20 some years ago, when the 8900 series was new.  My dad rented a dealer owned 8940 with a 5 shank inline subsoiler on it.  When I got in it I noticed there was some information missing on the dash.  MPH was one, might have been some others as well and the hour count wasn’t increasing.  Late in the day one of the dealer techs came sliding out unannounced, crawled under the right front of the cab, and fiddled with something.  After that the dash displayed everything it was supposed to.  “What did you do that for?”  “Well, I was the last one who rented this thing and I disconnected a wire harness so the tractor wouldn’t run up hours while it idled by me”.  Right, wink wink! 

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1 hour ago, ihrondiesel said:

Is there a picture of the bulkhead connector in a dealer knowledge article or similar publication that will tell me which pins I need to be checking?

This should get you going in the right direction. This starts at the cluster, goes through the rear connector located at the RF corner area of the cab and then to the transmission harness to the sensor itself. Photo of the connector shows the pin locations. 

0A0B8566-F5A2-45C5-9B37-255851837196.jpeg

B0EF5005-8939-42A3-9291-A5CA0DAAFD43.jpeg

C092948F-0F91-40BA-BBE7-0FF800A0B49E.jpeg

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Thanks, SDman!

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Thanks again to SDman’s pictures and all the other replies.  It’s working now. I cut the woes about 4” from the bulkhead connector and ran new wires to the ground speed sensor. A picture for the “pictures or it didn’t happen” crowd. 
72459CDE-21EA-41BF-BB18-04D9FBE40CA1.thumb.jpeg.72856537f8a0208fe198725cae1db173.jpeg

And a picture of the tractor for your enjoyment. 
7AFFA525-253F-45FE-B9DD-61304C353F06.thumb.jpeg.d063457565f62f8c83af7f46bf68a618.jpeg

24,000 hours and change. Repainted and overhauled before I bought it. Spent its previous life married to a lagoon pump. 

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Sorry double post . We have one 7250 Pro Euro Magnum we can't get the calibration number corrected and it says it does over a hundred miles an hour.

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Ron that thing looks pretty nice especially for those hours.

Not the hijack but as an example of how it uses engine RPM and transmission RPM to figure out what gear it is if you have an in tenth gear and you're climbing a hill and 10th gear is weak and you start slipping in that gear it'll show that you dropped a 9th gear as you keep slowing down now it'll say eighth gear if you keep slowing down the gears will keep dropping on the number on the dash yet you're still intense physical gear. It takes the transmission speed and converts that  into ground speed by a calibration number that is different for different tire sizes

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2 hours ago, ihrondiesel said:

Thanks again to SDman’s pictures and all the other replies.  It’s working now. I cut the woes about 4” from the bulkhead connector and ran new wires to the ground speed sensor. A picture for the “pictures or it didn’t happen” crowd. 
72459CDE-21EA-41BF-BB18-04D9FBE40CA1.thumb.jpeg.72856537f8a0208fe198725cae1db173.jpeg

And a picture of the tractor for your enjoyment. 
7AFFA525-253F-45FE-B9DD-61304C353F06.thumb.jpeg.d063457565f62f8c83af7f46bf68a618.jpeg

24,000 hours and change. Repainted and overhauled before I bought it. Spent its previous life married to a lagoon pump. 

Nice looking tractor. I know SD and the other guys have explained the shift and gear number before on here.

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On 7/6/2020 at 12:21 PM, Gearclash said:

This topic reminds of an incident that occurred 20 some years ago, when the 8900 series was new.  My dad rented a dealer owned 8940 with a 5 shank inline subsoiler on it.  When I got in it I noticed there was some information missing on the dash.  MPH was one, might have been some others as well and the hour count wasn’t increasing.  Late in the day one of the dealer techs came sliding out unannounced, crawled under the right front of the cab, and fiddled with something.  After that the dash displayed everything it was supposed to.  “What did you do that for?”  “Well, I was the last one who rented this thing and I disconnected a wire harness so the tractor wouldn’t run up hours while it idled by me”.  Right, wink wink! 

Your story reminds me of a customer from many years ago when those tractors were new. My old boss did business with this guy that I wouldn't trust a dead cat with. This guy rented a 71xx series Magnum from my old boss...when he brought it back my boss checked the hourmeter for the rent. This idiot claimed that "the hired man left the key on one weekend...so it counted up all those hours and I shouldn't have to pay for them". I realize back then that several machines did have electric hourmeters that were just wired up to the key switch...and they would count hours with just the key on....but not a Magnum. I told my boss that was just a BS story...that's not how they worked. The guy didn't put up a big argument...so his sense of reality came back real quick. However, after the guy left, I did show my old boss that if somebody unhooked the tach sensor...they wouldn't count hours. After that, he was kind of a stickler to make sure the tach was working on any/every Magnum he was looking at for a trade-in. 

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OH yeah.  Dealer hired a guy to demonstrate I believe a 2+2.    Neighbor of this guy saw him out in the field doing  his own farm tillage but no hours were showing on hourmeter.   Then he lied about it and end of that story.   

Back in the day a lot of cars would show very little mileage when kids had dad's cars for a date etc.  Even the girls were crawling under the dash to unhook the cable.  

My  boss's daughter got caught by Sheriff as she was backing down the road to erase a few miles.  I don't think she realized it would take so much going in reverse to get her back to her approved mileage limit. 

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