310G Tier II engine cranks but no start.

[Rick Blevins]

I have a 310G John Deere backhoe which was running perfectly. I shut it off one day and when returned five days later it will crank but not start. The backup alarm is constantly beeping with key on while in neutral and stops when I move the shifter to forward. Hydraulic fluid is okay, oil level is good and transmission fluid level is good. No active codes but did have F965, F457, F497 and F950 codes stored. I cleared those out and none return but still not starting. Sounds like is stuck in reverse with shift select in neutral but don’t know how could happen. Any help is appreciated.

 

[Tinkerer]

Welcome to HEF Rick !
mg2361 is the John Deere here expert and he will need a serial number to help you

 

[Rick Blevins]

Serial # T0310GX946207

 

[Rick Blevins]

Have not tried to fire off of ether yet but going to get some and try next

 

[Rick Blevins]

Did fire up on ether and I only allowed to run about 4 seconds. It would not shift into forward or reverse gear while running and died immediately.

 

[mg2361]

Welcome to HEF Rick!

Regardless of the B/U alarm issue, the engine should start.

All the fuses good?

Do the engine rpm's register in the monitor while cranking?

Good fuel supply and pressure to the injection pump.

If you know how to clear the codes, then you should know how to access the codes. Just because a code did not automatically pop up, doesn't mean one wasn't tripped.

 

[Rick Blevins]

Fuses all good.
Good fuel to pump.
I checked for all active and stored codes and none found.
When I crank engine I see no engine rpm. 0.0
Crank sensor wiring looks good to where it goes into main harness.

 

[mg2361]

If you have 0 rpm when cranking then there is a crank sensor/wiring issue.

 

[Rick Blevins]

My background is n automotive. Guessing crank sensor on this is same. Need crank ref to energize injection pump? Also is there a common failure in this? Unit has been running perfectly for months without issue. Just curious. And thanks for the help.

Also FYI. About 4-5 minutes before I shut it down for the night I went down about a 50 degree bank. Never stumbled or missed a bit. Just thought I might give all info about last use.

 

[mg2361]

I have seen a fair share of defective crank position sensors. It has a standard 2 wire inductive type crank sensor. It has no cam sensor. So if you lose the crank sensor, the engine will not run. Having a zero on the instrument cluster tells me the ECU is communication. If the ECU was not communicating, the the rpm would read dashes.

Crank sensor resistance should be 2700-3300 ohms. Check the tone wheel also to make sure it is tight.

 

[Rick Blevins]

Found it! It was the wiring to crank sensor after all. Did not notice as harness was secured tightly where issue was that I did not see. One broke and other almost broken about 2” from sensor connector where it goes into woven insulation. Harness was still zip tied to sensor from factory it appears but was such a sharp kink/bend there I guess it just finally broke. Repaired harness and immediately fires up. Thanks again for your help as your advice was spot on.
Rick