John Deere 997 Seat Safety Not Working

StarTech · Thursday at 4:32 PM

That's okay as I will DL a copy of the TM2259 for my shop too since I don't have that copy here. GFP hasn't responded to me yet.

Update

And I just looked over that TM2259 and it appears to be the correct manual. Tnx for the TM PN.

Partial seat switch circuit diagram. Boy I haven't seen a PNP transistor used in a long time.

Remove the module and temporary jumper green wires 640 and 641 together. This will bypass the time delay module for test purposes.

Auto Doc's · Thursday at 5:30 PM

jshep1102 said:
OK, the rain finally stopped and I got to dig a little deeper. I found a picture of a 2x2 pin configuration delay module that showed wire colors and I checked resistance reading that Kenbu posted on my 1x4 pin configuration delay module. They were very similar readings as shown in the attached pic so I don't think I have a bad delay module. More digging ensued.
Aha!, I found some more wire modification shenanigans put in place by a previous owner. Under the control panel, i found another jumper that picked up power off of one lead coming from to the ignition switch and fed it to a solenoid on the hydraulics pump. The other leg of the plug at the solenoid was jumpered to a wire on the PTO switch. Again, no idea why someone put this and the other jumper (delay module to fuel cutoff solenoid) in place. Not sure if the previous owner was a genius fixing a problem I haven't found yet or a hack just finding power/ground somewhere and using it willy-nilly to get something to work rather than fixing what was really wrong. Use of these blue piggyback splice connectors probably eliminates the genius probability.
I think I found the service manual on Ebay for this mower that should have schematics I can use to figure it out. I'll write the seller to confirm it covers my particular mower.
The saga continues...!

Hello J.,

When I see tap splices like that, it spells "rednecks and beer" around my area. Those things should be outlawed. Small utility trailer companies use them by the bags full, they are nothing but trouble.

Your test measurements are not terribly off, so I suggest you correct all the creative wire passing attempts and restore it back to original before you condemn the delay module.

Marine butt slices with sealant in them are ideal for this kind of repair. Wiring can be tedious, but if done correctly, it will last you for many years.

Last item I will mention is to remove all the cable ties that appear to be overtightened. That causes broken wire strands inside the wire insulation.

jshep1102 · Thursday at 7:13 PM

StarTech said:
That's okay as I will DL a copy of the TM2259 for my shop too since I don't have that copy here. GFP hasn't responded to me yet.

Update

And I just looked over that TM2259 and it appears to be the correct manual. Tnx for the TM PN.

Partial seat switch circuit diagram. Boy I haven't seen a PNP transistor used in a long time.
View attachment 72153
Remove the module and temporary jumper green wires 640 and 641 together. This will bypass the time delay module for test purposes.

OK, I've run out of daylight but we're getting closer (I think). Still weird response, this is what I have:
1. With key in "RUN" position, I have 12+VDC on yellow 509 at seat delay module (expected)
2. With key in "RUN", I do not have any voltage at yellow 510 at the seat switch (unexpected)
3. With key in "RUN", I do not have any voltage on green 641 at K2 seat relay (Unexpected)
4. However, in "RUN", I do have voltage at green 640 at delay module (unexpected) even with the seat switch unplugged. Obviously, i'm picking up 12V on green 640 somewhere but I haven't found out where yet. I'm guessing somewhere, the previous owner jumped 510 yellow to 640 green
5. I have a 5th wire attached to 87A terminal on the seat relay. Is it possible this partial schematic isn't applicable to my mower.

I like a good electrical troubleshooting problem. I got one here for sure. Thanks for hanging in there with me.

StarTech · Thursday at 7:46 PM

sorry i posted an earlier partial for before SN 020001

this is for the (S.N. 020001-050000) that 5th wire should be a pink wire [658].

StarTech · Friday at 8:17 AM

Sorry the attached is not super clear but even the service manual image are not very clear. But I spliced together multiple [6 pages] to give overall idea how this nightmare wiring is done.

jshep1102 · Friday at 10:53 AM

StarTech said:
Sorry the attached is not super clear but even the service manual image are not very clear. But I spliced together multiple [6 pages] to give overall idea how this nightmare wiring is done.

Perfect!!! Thanks so much. It'll take me a little time to decipher this but step one is to figure out why seat switch 510 yellow has no power. It seems it has to be a broken wire somewhere because 509 yellow has power at the seat delay module. Just gotta find the ghost or goblin in this machine here on Halloween!

Auto Doc's · Friday at 11:13 AM

If I read the 6-page diagram correctly the machine has to be running for the alternator to power that 510 circuit to the seat switch. I could not enlarge the diagram well enough on my laptop.

jshep1102 · Friday at 3:38 PM

Auto Doc's said:
If I read the 6-page diagram correctly the machine has to be running for the alternator to power that 510 circuit to the seat switch. I could not enlarge the diagram well enough on my laptop.

I thought the same thing when I saw the schematic but that yellow 510 is hot in the key ON position. It must provide field excitation to the alternator.

jshep1102 · Friday at 4:14 PM

Good News/Bad News
Good news - I found the problem w/ the seat safety switch not getting power. The previous owner was very tricky and spliced green and yellow wires going to the seat switch and buried the splice WAY up the factory loom that protects the wires. After several hours of tracing power through the circuits, I knew the yellow wire to the seat switch was compromised but the loom still looked like factory installation. Eventually, I pulled that wire/loom and found the latest shenanigans. Seat safety now kills the mower if you get out of the seat while deck is engaged. Pics attached.

Bad news - I disabled rogue jumper #2 (from PTO switch to PTO solenoid) and plugged in the original wires. The PTO won't engage now (kinda figured that would happen because I didn't find any problems yet that would have caused the previous owner to install it). The funny part now (I can't make this stuff up) is with the PTO switch OFF, getting out of the seat causes the deck to engage. That doesn't sound safe.

More schematic studying and wiring tracing to follow.

Thanks so much for all your help getting me this far. The 6 page schematic allowed me to test a LOT of components to narrow it down to the actual problem. I'll use the schematic to solve the newest problem too.

Auto Doc's · Friday at 6:02 PM

jshep1102 said:
I thought the same thing when I saw the schematic but that yellow 510 is hot in the key ON position. It must provide field excitation to the alternator.

Thanks for the updates as you are progressing. I see so many smaller units, that I forgot this actually has a real alternator.

John Deere 997 Seat Safety Not Working

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