Mechanic: Kevin, Technician replied 5 years ago
It sounds like the HCU controller lost it's calibration.
We can attempt recalibrating the hitch controller however if it passes and then goes back to setting HCU 28 shortly there after then the controller will need to be replaced.
The following steps will walk you through the hitch calibration procedure.
1) Operate the tractor until the hydraulic oil is up to normal operating temperature. Oil must be a minimum of 135 degrees in order for the calibration procedure to done.
2) Set the hitch controls as follows: Load and depth knob full clockwise, raise limit full clockwise, rate of drop knob full clockwise, depth control lever full down, manually lower the hitch to the fully lowered position.
3) If you do not have a quick hitch on the three point hang at least 250lbs of weight on the hitch but not more then 400lbs and make sure that it does not restrict full range of motion.
4) Install the diagnostic fuse and set engine rpm's to 1200 rpm.
5) Use the turn signal lever as before to reach the HCU controller and pull the flash to pass to enter the controller address list.
Use the turn signal switch to access address 19 which shows the transmission temp in Celsius and make sure that the oil temp is above 58 degrees Celsius. A jumper hose on the rear SCV can be used to circulate oil for warm up.
6) Use the turn signal switch to access address 20 and hold in flash to pass mode momentarily to access the calibration. The display should read 20 CAL.
7) Raise and lower the hitch 5 times using the up and down switch ending in the lowered position.
The display will change from 001, 000, 002 indicating the up and down switch position.
8) Slowly pull the depth control lever full rearward to the transport lock position, then full forward, then full rearward again ending in the transport lock position.
The display should read 20 100.
9) Turn the raise limit knob full counter clockwise slowly and then full clock wise.
10) Turn the raise limit knob full counter clockwise slowly, the hitch should drop part way down and stop.
11) Pusch the depth control lever full forward slowly and then full rearward back to the transport lock position. The hitch should return to the full up position.
12) Turn the raise limit knob full clockwise and then full counter clockwise.
The hitch should again drop part way down and stop.
13) Push the hitch control lever full forward, the hitch should drop all the way down.
14) Turn the raise limit knob full clockwise slowly, then full counter clockwise, and then back to full clockwise.
The hitch should raise part way.
15) Pull the hitch control lever full rearward and then full forward.
The hitch should raise then drop to the fully lowered position.
16) Turn the raise limit knob full counter clockwise and then full clockwise. The hitch should raise part way.
17) The next step requires us to tell the HCU what lift cylinders the tractor is equipped with.
To do this we need to know if you have two 70mm cylinders, or one 70mm and one 80mm, or two 80mm.
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If you have two 70mm cylinders pull the depth control lever back until the display reads 121, if you have one 70mm and one 80mm cylinder pull the lever back until the display reads 126, or if you have two 80mm cylinders pull the depth control lever until the display reads 130.
Once the correct number is ***** do not move the depth control lever until the calibration procedure has been completed.
18) Turn the rate of drop knob full counter clockwise and then full clockwise.
19) Turn the load and depth knob full counter clockwise and then full clockwise slowly.
20) Turn the load and depth knob counter clockwise until the display reads 164.
21) Turn the rate of drop knob full counter clockwise and then back to full clockwise.
22) Hold the hitch raise lower switch in the lower position until the hitch moves full down.
23) Hold your external (fender mounted) raise lower switch in the raise position until the hitch moves and then release it.
24) Raise the hitch to the full up position using the external raise lower switch.
25) Hold the external raise lower switch in the lower position until the hitch moved down and then release it.
26) Remove the Diagnostic fuse to store the calibration.
If ANY of the above steps are done incorrectly the calibration will fail and must be restarted from the beginning.
This also means that if your external raise lower switch is faulty the calibration will fail.
If you get "ERR" at any point in the calibration go back to HCU address 001 and recheck the stored codes. Any codes other then 28 may indicate a hitch component fault.
I know this procedure is a pain in the rear but it is the only way to regain full hitch function.
Please keep me posted as to the outcome or if there is anything further I can do to asset you with this problem.