# John Deere utility tractor neutral safety switch



## Wethay (Jul 17, 2015)

I have a John Deere 2155 tractor. It has a two stick transmission and the left hand gearshift (range selection) has to be in neutral for the tractor to start. If the tractor is running and the gearshift is moved out of neutral with the parking brake applied a audible warning is sounded. A few days ago the tractor was giving me an audible warning when I applied the parking brake even though it was in neutral. I got done with what I needed to that day without shutting the tractor off. Upon parking it I tried to restart it with the predicted results of it not starting. After a bunch of head scratching and unchurch like language I narrowed the problem down to a section of the wiring harness that John Deere calls a "ground cable". All it is is two wires terminating in one end in a two place weather pack seal and on the other end into spade connectors. It's basically an adapter that goes from the weather pack connector on the wires coming out of the neutral safety switch to the spade connectors on the two separate wires the wiring harness. One of the wires in this adapter has 3 heat shrinked over bumps. I assume that two of them are butt type connectors and the middle one is most likely a diode. According to the parts book and the parts man this was done on much later production tractors than mine. On my production model there was not the adapter, a different neutral safety switch part number and a lower amperage fuse in the system. Can anybody tell me what this update does, and why the need for what I assume to be a diode in the circuit?


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## Tx Jim (Jun 30, 2014)

Have you checked that ground on this wire is clean & tight? What's your tractors serial number & is it MFWD? You can PM me the SN if you don't want to publish it.


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## Wethay (Jul 17, 2015)

John Deere calls it a ground wire, but it isn't. 2 wheel drive, serial # below 618000. John Deere part #AL66133.


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## Tx Jim (Jun 30, 2014)

If you'll look at the parts photo notice 3 items I've circled that are ground connections. The way I comprehend the wire routing the wiring AL66133(key 8) plugs into main wiring(key 3) which has grounds that need to have continuity.


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## Wethay (Jul 17, 2015)

Sorry I wasn't clear. The problem I'm having is the tractor not believing it is in neutral. I have power to the neutral safety switch and continuity through the switch. The problem is the magic smoke installed in one of the wires in part number 8. I was mainly wondering what the update was supposed to do. John Deere wants $60 for that short chunk of two wire and a couple couplers so I thought about trying to find out what kind of magic smoke was spliced in and out sourcing it.


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## Tx Jim (Jun 30, 2014)

IMHO the only way to correctly answer your question is by studying the wiring schematic for your model tractor.OR you could just wire neutral start switch so starter would operate correctly.


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## Farmineer95 (Aug 11, 2014)

They had a replacement plug to replace the 2 terminal slip on plug to the neutral switch. Think the wires were white. Nothing special about them, was a butt connector with shrink wrap. The connector was all metal, not like the plastic sleeved ones in your tool box. Wires were maybe 6"long coming out of the plug. Maybe someone replaced the plug already? Open the shrink wrap and make sure it's just a connector, no diode. That series had a different (not a simple as it could been), had an extra relay
Did the parking brake alarm always work?


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