Hi I want to recalibrate as Counter Rotation is not working. FNR works. Re-calibration stops after 45E stops flashing. Release decelerator pedal does not make the 4 go out. I am following the TM1588 technical manual. The first step in this manual is to Check Engine Speed Adjustment - 750C group 9010-20. This manual says it should be 900 +50. My engine low idle speed is 850 so I didn't go thru this procedure. Is this necessary? Are there other reasons for going thru this procedure other than specific idle rpm? Thanks Wayne M
Yep. It may not be the engine speed as well. It could be the voltage at the sensor is out of adjustment. However, in a pinch, you could try to manipulate your pedal position to see if it will go through. I have been successful trying that about 1 in 10 attempts.
Ok thanks. I will go review the Engine Speed Adjustment procedure and try it.
Do I need the JT07237-1 and -2 special wiring connector kit to do the decel sensor adjustment? Thanks
Nope. You can backprobe the connections to get the voltage readings. I suggest using something like this:
Thanks MG. I will order that probe
Hi MG. I have probed the Decel sensor and get 5.06 volts red wire, 3.06 v with pedal released, 1.26 v with pedal fully depressed which meet specs in manual. Also, set engine rpm at the fuel pump with magnetic tachometer. Monitor says 1080 rpm for released Decel and 920 rpm for depressed Decel. Using manual TM1588 and P 540 sensor signal wire runs straight to TCU. I continued with the calibration and got the counter rotate to work after installing a new Steering Rotational sensor. Now only get the 4 Decel error and F629 which is the left speed sensor, which I will replace. Any ideas on why the 4 will not go out? Is it advisable to remove the connector on the TCU and test for 3.06 and 1.26 volts there? Thanks Again. Wayne
I should have mentioned that on P 777 of the manual it says that when error 4 remains in the monitor window during calibration of decelerator, voltage range has not been met. Also, I have a can of John Deere Electrical contact spray. Would it be advisable to spray this on the TCU connector, assuming there might be some contamination of the pin/receptable?
The controller also looks at rpm. It gets it information from the hydrostatic pump speed sensor. think the 1080 rpm would be too high. Isn't the spec 100-150 rpm higher than 900? Does the monitor match the tach you used? If none of that works, you could try not quite letting the decel pedal all the way up after the first step, just to see if the 4 goes out. That would be a good idea. That way you know if the proper voltage signal is reaching the TCU. Go for it. It won't hurt a thing. If there are any crusties in any connector, the best spray for that is
Thanks MG. Yes, the slow idle rpm is 900 + 100-150 rpm, so I will bring the engine speed lever down a little. There may have been an issue with short decelerator travel. It only travels about 1/2 inch it seems, from released to depressed. Let me check this again. I will examine the TCU connector as well. This will take a couple of days. Finished haying and trying to get ready for winter.
Hi MG Replaced the left speed sensor and back probe tested the new one and all voltage specs were met. So this eased my mind about there being a speed ring issue. Ran the calibration procedure again and dozer is now very responsive and quick and travels in a straight path - both forward and reverse. The 4 went out in the 267 calibration sequence? Big job as I had to remove the ripper before replacing and re-install after calibrating and testing. Thanks Again