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Discussion Starter · #1 ·
I'm getting a "No Start" condition. No Fuel Prime cycle when key is turned, engine cranks normally, but doesn't start.

The Fuel Pump is OK, it runs when the terminals of the Fuel Pump Relay are jumped.

The Fuel Pump Relay has a good 12V at the coil terminal, however, the Relay Ground (Green Wire) has no continuity to Chassis Ground.

I've done substantial disassembly, seats out, center console out, unmounted ECU box, unmounted Relay 'Box', buzzed out wires to Fuel Pump Relay,

The Green Wire from the Relay enters the front main harness, and exits at a large connector where it enters the smaller ECU harness and changes gauge to a smaller green wire.

Somewhere between the connector under the hood and the middle of the seating area I'm losing the smaller Green Wire.

I'm assuming that that wire goes to the Fuel Pressure Sensor, and should provide a normally closed connection to GND until the fuel pressure in the reail builds to nominal, when the connection goes open, turning off the Fuel Pump Relay and the Fuel Pump.

I cannot find a Fuel Pressure Sensor!

I'm wondering if this wire enters the harness & has a stump or turns back and goes to the ECU. I don't want to peel the entire harness looking for the a loop wire. So I need some guidance or reassurance. Or a wiring diagram...

I've already seen one of the biggest NO-NO's in (aerospace) wiring harness econstruction, a fistfull (~6) of yellow (Ignition ON?) wires from one direction are joined & spliced to a handful (~4) of the same Yellow going the other direction.

Sorry for the long post, I want to be thorough in describing the problem and the background.

FWIW: I bought my Gator at a Ritchie Bros Auction this summer. So far it's spent more time in the yard at the local Deere shop than on my property. It received a comprehensive maintenance, all fluids, R&R 4WD parts, brakes, new wheels, etc., etc... Since I got it back, I think I've used a bit less than a 1/2 tank of fuel in total. It's only got 540 HRS & 1700 miles on the meter. When I purchased it it appeared reasonably clean, however since yesterday I've discovered that it it was apparently packed solid with fine clayey mud.
The center console where the wiring harnesses run was heavily caked.

So far I've removed the wiring for a sand/salt spreader (two wires to the battery, and a speed control in the glove box, connected to air), and an Asset Tracking Device. Only three wires -- Red (+12), Black (GND), White (ignition), which they seemed to have removed a five wire connector from the Front Harness on the driver's side. There remains a center roof beacon that was destroyed.

I've attached a winch (two wires to the battery) to raise & lower a landscape rake from the rear hitch. The No Start has happened before, but was intermittent. After attaching the winch, it happened again in the work area, and so that prompted the removal of the tracking device. I confirmed with Verizon that it was only being used to sense asset utilization and had no capability to disable anything with only the three wire configuration.
 

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Are you certain about your assumption there is a fuel pressure sensor? Most ECU's turn on for a prescribe time and don't use a sensor. Perhaps verify by searching the illustrated parts at www.jdparts.com

The Technical manual and it's wiring diagrams would be of help, but of course they cost money and most people don't want to pay for information.

Since you've identified the continuity issue why not isolate by disconnecting wire terminals? Once isolated it might be a pain to interrogate the harness further but at least the search location would be easier.

Are you certain the ECU doesn't switch to ground and why there is no continuity with KO? Again, the TM has sections describing how the systems work called theory of operation.

Wish I owned a similar model to help further.

Good luck and report back what you find.

Happy Thanksgiving!
 

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Discussion Starter · #3 ·
Hi, thanks for the reply.

No, I'm not certain about the sensor. I traced the wire into the connector for the engine harness, but lost it somewhere inside up under the dash. I've been searching for several days and fount a diagram from an older model that shows the source as pins 3,6 on the potted control board assy. Going to try to verify that today. I'd've checked that earlier but I does not appear to be either green nor blue wire at that connector.

If there is no fuel pressure sensor then I have a feeling that I'm dealing with a defective transistor somewhere in that potted assembly.
 
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