John Deere 997 Seat Safety Not Working

[jshep1102]

Hi guys,
I'm working on a John Deere 997 Z-Trak for a friend and I'm trying to get the seat safety switch to work. I think it may be an early 2000's model (ID# DM997SC020068).

Complaint - mower will not cut off while mower deck is engaged and you lift your butt out of the seat.

Things I've done/found:
1. Seat safety switch confirmed to close when switch depressed and open when nobody in the seat.
2. Mower start and runs/mows normally otherwise.
3. neutral safeties both confirmed to work: i.e. mower won't start with either lever out of neutral position (don't think it has anything to do with the problem but I checked it anyways).
4. Brake safety works as expected (again, don't think it has anything to do with the problem but I checked it anyways)
5. Previous owner had a jumper piggybacked from red wire of seat timer delay module running to the red wire on shutoff solenoid valve. No idea why it was installed so I disconnected it and everything is still acting the same.
6. Seat timer delay module has zero VDC on red wire with key off and 12+VDC with key in run position. (4 pin plug associated with this module)
7. I swapped the Start relay (7th of 10 relays) with the Seat relay (9th of 10 relays) to see if it was a bad seat relay. No change. Mower still starts and seat switch still not working.

Could it just be a bad seat delay module? Thanks in advance for any help you can provide.
Jerry

 

[jshep1102]

Does anyone have a good electrical schematic I can get? I have the Owners Manual and an Operators Manual but neither of them have a schematic.

 

[Kenbu]

Similar thread on another forum https://www.greentractortalk.com/threads/z997-safety-switch-problems.229060/

 

[StarTech]

If this is a Z997R then you need to get a copy of the TM132819 technical manual which would the schematic. That is if you can afford $15.

But most likely ECU has failed. I seen a lot problems on other JD units that uses these control modules. Most I was able to bypasses on but this seat switch circuit can't simply be bypass to get the system to work as intended.

 

[jshep1102]

Similar thread on another forum https://www.greentractortalk.com/threads/z997-safety-switch-problems.229060/

I saw that thread but it's addressing a problem a little different than the one I'm having. It also has a different style of time delay module. It has 4 pins in a 2x2 configuration. Mine is a 4 pin in a flat configuration. Thanks for the response though.

 

[jshep1102]

If this is a Z997R then you need to get a copy of the TM132819 technical manual which would the schematic. That is if you can afford $15.

But most likely ECU has failed. I seen a lot problems on other JD units that uses these control modules. Most I was able to bypasses on but this seat switch circuit can't simply be bypass to get the system to work as intended.

Thanks StarTech. I can't tell if this mower is the "R" version of the 997. No labels anywhere show an "R" after the 997. For $15, I'd gladly get the tech manual. Where's the best place to get it?

 

[Auto Doc's]

Thanks StarTech. I can't tell if this mower is the "R" version of the 997. No labels anywhere show an "R" after the 997. For $15, I'd gladly get the tech manual. Where's the best place to get it?
View attachment 72120View attachment 72121

Hello J.,

Remove the screws from the right side (has seated on the machine), lift up the control panel and look for a red or black square "box" plug-in interlock diode. I recently had a JD 757 zero turn that shorted out the seat harness and popped the diode. Now it does not have the diode to interfere with the operations.

If this model has the time delay control module (magic box) disregard searching for the diode mentioned.

 

[StarTech]

2006 Model (Serial No. DM997SC020001-030100)

IPL don't show an ECU instead a mess of relays so this is not a "R" series. Darn it. Have to contact JD for what is the correct service manual PN.

 

[jshep1102]

2006 Model (Serial No. DM997SC020001-030100)

IPL don't show an ECU instead a mess of relays so this is not a "R" series. Darn it. Have to contact JD for what is the correct service manual PN.

Thanks Star
Well, that explains why I couldn't find an ECU anywhere on that tractor. 10 relays in a row above the engine.

 

[jshep1102]

Hello J.,

Remove the screws from the right side (has seated on the machine), lift up the control panel and look for a red or black square "box" plug-in interlock diode. I recently had a JD 757 zero turn that shorted out the seat harness and popped the diode. Now it does not have the diode to interfere with the operations.

If this model has the time delay control module (magic box) disregard searching for the diode mentioned.

AutoDoc,
It has a 4 pin connector for the seat control module like the one shown in the attachment. It that the magic box you were thinking about?