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Service Bulletin NTR SB 026 96
Magnum Hitch Diagnostic Codes and Service Manual update

Page 18 of 26

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HITCH VALVE COMPONENTS AND FUNCTION CONTINUED

Control spool
Raise -

 Once the control spool is shifted to the right it then directs PFC pump pressure to the left

end of the lockout plunger spool (the lockout spool dose not move) but the pressure in that area
will unseat the load check poppet to raise the hitch.

Lower 

-

 Once The control spool is shifted to the left it then directs PFC pump oil to the right end

of the lockout plunger spool which (unseats) pushes the lock check poppet to the left to lower the

hitch.
- If the control spool stick in the center position the hitch won’t raise or lower.
- if the control spool sticks to the left, the hitch will drift down.
- If the control spool sticks to the right, the hitch will drift up.

Lockout plunger spool

Raise 

-

 The lockout plunger spool is not shifted or moved with oil pressure when the hitch is

raised. The piston pump oil pressure at the left end of the spool will unseat the load check poppet

to raise the hitch.

Lower -

 The lockout plunger is shifted to the left with piston pump pressure. The lockout spool

pushes the load check poppet to the left to lower the hitch.
- If the lockout plunger spool sticks to the right, the hitch won’t lower.

-

 If the lockout plunger spool sticks to the left the hitch will settle.

Load check poppet

The load check poppet prevents the hitch from settling when the engine is turned “off” or when

the hitch valve is in neutral (solenoid not powered by hitch control module).

The load check plunger must shift to the left for the hitch to raise or lower.

- If the load check poppet sticks to the left the hitch will settle.

Signal check valve

The hitch signal check valve isolate the piston pump signal circuit from the Steering valve, remote

valves and the power beyond valve. The PFC pump pressure will be set by the valve producing
the highest signal pressure.

Summary of Contents for Magnum 7210

Page 1: ...bration procedure This bulletin will cover the following items 1 General information page 2 2 General testing of the hitch system Reading and erasing error codes page 3 4 3 page 5 4 Hitch performance...

Page 2: ...ay not show up as error codes The hitch must be recalibrated every time an hitch component is replaced or adjusted An empty hitch may move up slightly when the tractor is backed up if the load setting...

Page 3: ...number JJA0064978 a Check battery and cab power stud located on cab floor RH console b Fuse 7 may be defective c Turn key ON and check pin 14 of the 16 pin connector for power d Bad ground to control...

Page 4: ...ormation Electrically testing the hitch valve solenoid Disconnect the 16 pin connector from the hitch control module Test the hitch harness and solenoid resistance Solenoid spec 3 8 4 2 ohms 1 Raise s...

Page 5: ...ve been recorded recorded first code will appear now A If any error codes have been I Toggle to UP position Toggle to DOWN position I Down momentary and release I c l Next error code Example only Repe...

Page 6: ...responding to the various error code displays are HALT LIMP DEGRADED 2 and DEGRADED 1 each failure mode will generate different modes of operation as follows MODE OPERATIONAL HITCH FUNCTIONS HALT Hitc...

Page 7: ...cuit failed i EEPROM failure The system cannot read calibrated values or errors HALT Tractor has not been calibrated Only appears when controller has been replaced HALT Calibrate hitch controller 1 Sh...

Page 8: ...r El Relay primary or contacts problem Watchdog circuit problem High battery supply voltage Upper limit circuit failed Load control circuit failure 5 Both draft pin sensors failed or one draft pin sen...

Page 9: ...er rest wire harness for damaged wires or connectors 4 Lamp circuit failure DEGRADED 1 Replace lamp lest wires to lamp for damaged wires or connectors DEGRADED 1 Capture the hitch and lower the hitch...

Page 10: ...oller RAISE LOWER switch and position control failure LIMP Replace RAISE LOWER switch and Test position sensor wire harness Replace posrtion potentiometer Replace controller RAISE LOWER switch failure...

Page 11: ...the test box at position 1 set D C voltage to 4 85 1 volts Adjust the hitch position pot in the console if needed See Service Manual 8009 8 steps 16 21 Test position pot Set the DVM to the 2 decimal...

Page 12: ...full raise position Raise the hitch by pressing the hitch switch to the MOMENTARY position and releasing the switch The hitch position lever should still be in the transport position A 9 should appear...

Page 13: ...sition command is not at maximum Raise PWM Pulse Width Modulation threshold is above 55 Raise PWM Pulse Width Modulation threshold is below 4 Full raise current detection 100 Pulse With Modulation is...

Page 14: ...low A Replace coil 0 B Battery voltage is very high B Test tractor battery circuit output Hitch valve null out of adjustment C Valve failure C Repair or replace hitch control valve Md A Operator did n...

Page 15: ...r leaking 9 High pressure stand by not in spec 3 Hitch will not lower A B C D E F Perform Electronic Hitch Control troubleshooting Troubleshooting hitch system page 4 Hitch drop speed control set inco...

Page 16: ...er If hitch leaks still leaks down go to step B Testing the hitch rockshaft cylinder and the cushion relief valve 1 2 3 4 5 Lower the hitch completely Disconnect the hitch supply line to the rockshaft...

Page 17: ...S Pin B to pin C 3 8 4 2 OHMS If the plunger in the solenoid valve is off center to the right the hitch will drift up If the plunger in the solenoid valve is off center to the left the hitch will drif...

Page 18: ...lockout plunger spool is not shifted or moved with oil pressure when the hitch is raised The piston pump oil pressure at the left end of the spool will unseat the load check poppet to raise the hitch...

Page 19: ...isplay will not work on 7100 series 235010A1 ELIMINATING DRAFT CONTROL FROM THE MAGNUM TRACTOR Load pins draft control can be eliminated from the tractor by simply unplugging the draft pins and reprog...

Page 20: ...ximately to 9 1 volts D C in the fully lowered position Note To completely lower the hitch the up down switch must be double clicked and held in the momentary position Note The over all range of the r...

Page 21: ...Pin B of the Load control potentiometer signal Pin C of the Load control potentiometer ground See secondary control panel for potentiometer spec See page 22 Pin A of the Travel control potentiometer p...

Page 22: ...al Pin A of the Hitch position rockshaft potentiometer ground See Testing hitch potentiometer on page 20 See correction to wiring schematic on page 26 OHMS 195 000 195 000 OHMS OHMS Cab floor I d b d...

Page 23: ...lay To terminal A of the fender mounted hitch control switches POWER SUPPLY TRACTORS ABOVE SERIAL NUMBER JJA0064978 Turn key switch ON the ignition cab relay should provide power to fuse 7 If fuse 7 i...

Page 24: ......

Page 25: ...7 Terminal 87 of the EDC relay supplies 12 volt power to the following To pin number 14 of the 16 pin connector To terminal 30 of the hitch enable relay To terminal 5 of the up down switch To terminal...

Page 26: ...date Page 26 of 26 CORRECTION TO WIRING SCHEMATIC The rockshaft position sensor wiring schematic is incorrect in the Service Manual schematic found in section 4002 page 27 See below for correction INC...

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