Grasshopper 720 Service Manual
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Grasshopper 720 Service Manual

Electrical troubleshooting all models with modular wiring serial numbers 310000 through 469999; volume 1
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SERVICE MANUAL

E
LECTRICAL TROUBLESHOOTING
V
1
OLUME
A
LL MODELS WITH MODULAR WIRING
S
ERIAL NUMBERS 310000 THROUGH 469999
THE GRASSHOPPER COMPANY
Moundridge, Kansas 67107 U.S.A.
PHONE (620) 345-8621
FAX (620) 345-2301
PRICE $12.00
Rev. 01-95
Form 172110
Printed in U.S.A.

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  • Page 1: Service Manual

    SERVICE MANUAL LECTRICAL TROUBLESHOOTING OLUME LL MODELS WITH MODULAR WIRING ERIAL NUMBERS 310000 THROUGH 469999 THE GRASSHOPPER COMPANY Moundridge, Kansas 67107 U.S.A. PHONE (620) 345-8621 FAX (620) 345-2301 PRICE $12.00 Rev. 01-95 Form 172110 Printed in U.S.A.

  • Page 2: Introduction

    Copyright © 1995, 1994, 1990 by The Grasshopper Company. The following material is proprietary information. All rights reserved. Reproduction or dissemination in any form by any means is prohibited, except by express written permission from The Grasshopper Company.

  • Page 3: Table Of Contents

    Model 718D and 721D ....................8 Control relay - Model 720, 718D, 721, 721D, and 725 ..........9 Circuit board diode problems - Model 720, 718D, 721, 721D, and 725..... 9 FUSE BLOCK DIAGRAMS TESTING SAFETY SYSTEM FOR PROPER OPERATION Model 612, 614, 616, 718, 718K and 720K .............
  • Page 4 WHEN KEY SWITCH IS RELEASED Model 718D and 721D (Kubota diesel engines) ..........38-39 TROUBLESHOOTING PTO CLUTCH Model 612, 614, 616, 718, 718K and 720K ............. 40 Model 718D, 720, 721, 721D and 725 ..............41 1994 MODEL UPDATES 42-44...

  • Page 5: Symbols Used On Wiring Diagrams

    SYMBOLS USED ON WIRING DIAGRAMS Indicates a ground point. Indicates wires crossover but are not connected. Symbol indicating wires are connected. Symbol for a diode. The arrow indicates the direction of current flow. Current will not flow in the other direction if the diode is working properly.

  • Page 6: Switch Functions

    M Magneto terminal. S Starter terminal. B Battery terminal. L Lights, accessory terminal. G Ground terminal. Ignition switch, part no. 183830. (Model 720). R Regulator terminal. A (Not used). B Battery terminal. S Starter terminal. I Ignition terminal. Ignition switch, part no. 183825.

  • Page 7: Switch Functions

    SWITCH FUNCTIONS Left and right steering switch, part no. 183860. NC (normally closed) - means that the contact is closed with the switch mechanism released. The contact position is reversed when the switch COM M ON lever is depressed. NO (normally open) - means that the RELEASED contact is open with the switch mechanism released.

  • Page 8: Troubleshooting Control Relays

    TROUBLESHOOTING CONTROL RELAYS MODELS 720, 721, AND 725. MODELS 718D AND 721D. 1. Control relay - inspection. 1. Control relay - inspection. A. Control relay A has 2 red wires, 1 A. Control relay A has 2 red wires, 1...

  • Page 9: Control Relay - Model 720, 718D, 721, 721D, And 725

    Control Relay - Model 720, 718D, 721, Circuit Board Diode Problems - Model 721D, and 725 720, 718D, 721, 721D, and 725 Assuming a normal diode on the circuit, Refer to the illustration below to locate the board, relay B is affected by a problem in...

  • Page 10: Fuse Block Diagrams

    The dotted line indicates an electrical connection between the two terminal posts. LI GHT Figure 3 M AI N REG. MODELS 718D, 720, 721, 721D, 725. The dotted line indicates an electrical connection between the two terminal posts. I GN. START Figure 4...

  • Page 11: Testing Safety System For Proper Operation

    TESTING SAFETY SYSTEM FOR PROPER OPERATION MODEL612, 614, 616, 718, Notes: Steering levers 718K, 720K Proper operation of the safety out, PTO switch system indicates that: 'OFF', and 1. To start the engine, the operator operator 'ON' must be on the seat, both steering seat.

  • Page 12: Model 720 (Onan), 718D, 721D, 721 And 725

    TESTING SAFETY SYSTEM FOR PROPER OPERATION MODEL 720(Onan), 718D, 721D, 721 and 725 Notes: Steering levers Proper operation of the safety out, PTO switch system indicates that: 'OFF', parking 1. To start the engine, both steering brake 'OFF', levers must be out, and the PTO operator 'OFF' switch must be off.

  • Page 13: Battery Charging System

    BATTERY CHARGING SYSTEM MODEL 718 Notes: Engine is not (Briggs & Stratton Twin-II engine) 1. Voltage tests are performed running. with a DC/AC voltmeter. 2. Tests are performed after Attach voltmeter regulator fuse is checked. to negative and 3. AC voltage tests are performed positive posts of with engine at 3600 rpm.

  • Page 14: Model 718K And 720K (Kohler Magnum & Command Engines)

    BATTERY CHARGING SYSTEM Engine is not MODEL 612, 614, 616, and 718 Notes: running. (Briggs & Stratton Vanguard 1. Voltage tests are performed engines) with a DC/AC voltmeter. Attach voltmeter MODEL 718K and 720K 2. Tests are performed after to negative and (Kohler Magnum &...

  • Page 15: Model 720 (Onan Engine)

    BATTERY CHARGING SYSTEM MODEL 720 Notes: Engine is not (Onan engine) 1. Voltage tests are performed running. with a DC/AC voltmeter. 2. Tests are performed after Attach voltmeter regulator fuse is checked. to negative and 3. AC voltage tests are performed positive posts of with engine at 3600 rpm.

  • Page 16: Model 718D, 721, 721D, And 725 (All Kubota Engines)

    BATTERY CHARGING SYSTEM MODEL 718D, 721, 721D, 725 Notes: Engine is not (All Kubota engines) 1. Voltage tests are performed running. with a DC/AC voltmeter. 2. Tests are performed after Attach voltmeter regulator fuse is checked. to negative and 3. AC voltage tests are performed positive posts of with engine at 3600 rpm.
  • Page 17 This page is intentionally left blank.

  • Page 18: Engine Will Not Crank

    ENGINE WILL NOT CRANK MODEL 612, 614 and 616. NOTES: Test battery for (Briggs & Stratton engines) 1. To see the wiring diagram for condition and models with serial numbers of charge. 340725 and higher, refer to Steering levers figure 40 on page 42. out, PTO switch 'OFF', operator on seat.

  • Page 19: Engine Will Not Crank

    ENGINE WILL NOT CRANK MODEL 612, 614 and 616. (Briggs & Stratton engines) continued VOLT M ETER Key switch is RED LEAD now OFF. You are now testing a ground circuit. All tests will be to the battery positive (hot) STARTER SOLENOI D side.

  • Page 20: Model 718 (Briggs & Stratton Vanguard Engines)

    ENGINE WILL NOT CRANK MODEL 718. NOTES: Test battery for (Briggs & Stratton Twin II 1. To see the wiring diagram for condition and and Vanguard engines) models with serial numbers of charge. 340725 and higher, refer to Steering levers figure 41 on page 42.

  • Page 21: Engine Will Not Crank

    ENGINE WILL NOT CRANK MODEL 718. (Briggs & Stratton Twin II and Vanguard engines) continued VOLT M ETER Key switch is now OFF. You RED LEAD are now testing a ground circuit. All tests will be to the battery positive (hot) STARTER SOLENOI D side.

  • Page 22: Model 718K (Kohler Magnum Engine)

    ENGINE WILL NOT CRANK MODEL 718K. Test battery for (Kohler Magnum engines) condition and charge. Steering levers out, PTO switch 'OFF', operator on seat. Voltage tests are performed with a voltmeter or test light to battery ground. Key switch is held in 'START' position for each test until...

  • Page 23: Engine Will Not Crank

    ENGINE WILL NOT CRANK MODEL 718K. (Kohler Magnum engines) continued VOLT M ETER Key switch is now OFF. You RED LEAD are now testing a ground circuit. All tests will be to the battery positive (hot) STARTER SOLENOI D side. Check starter Does the yellow solenoid.

  • Page 24: Model 718K And 720K (Kohler Command Engines)

    ENGINE WILL NOT CRANK MODEL 718K and 720K. NOTES: Test battery for (Kohler Command engines) 1. To see the wiring diagram for condition and models with serial numbers of charge. 340725 and higher, refer to figure 42 on page 43. Steering levers out, PTO switch 'OFF', operator...

  • Page 25: Engine Will Not Crank

    ENGINE WILL NOT CRANK MODEL 718K and 720K. (Kohler Command engines) continued If all safet y sw it c hes are c orrec t , t erm inal 86 is grounded. Key switch is Term inal 87 is 12 volt s. Term inal 85 is + 12 volt s w hen k ey sw it c h is in now OFF.

  • Page 26: Model 720 (Onan Engine)

    ENGINE WILL NOT CRANK MODEL 720 Test battery for (Onan engine) condition and charge. Steering levers out, PTO switch 'OFF'. Voltage tests are performed with a voltmeter or test light to battery ground. Key switch is held in 'START' position for each test until otherwise noted.
  • Page 27 ENGINE WILL NOT CRANK MODEL 720 (Onan engine) Figure 19 M AI N REG. I GN. START Figure 20 RI GHT LEFT SWI TCH STEER STEER SWI TCH IN START POSITION PTO OFF STEERING LEVERS OUT START FUSE STARTER RELAY B...

  • Page 28: Model 718D, 721, 721D, And 725 (All Kubota Engines)

    ENGINE WILL NOT CRANK MODEL 718D, 721, 721D, and NOTES: Test battery for 1. To see the wiring diagram for condition and (All Kubota engines) models with serial numbers of charge. 340725 and higher, refer to Steering levers figure 43 on page 43. out and PTO switch 'OFF'.

  • Page 29: Engine Will Not Crank

    ENGINE WILL NOT CRANK MODEL 718D, 721, 721D, and continued (All Kubota engines) Key switch is now OFF. You are now testing a ground circuit. All tests will be to the battery positive (hot) side. Figure 22 Remove relay 'B'. (Note: Relay 'B' is the relay M AI N REG.

  • Page 30: Engine Will Crank, But Not Start

    ENGINE WILL CRANK, BUT NOT START MODEL 612, 614, 616, 718, 718K, and 720K If engine (All engines) cranks, but will not run; the safety switches are functioning properly. Disconnect Interlock module yellow wire from or associated engine and test. wiring is Does spark defective.

  • Page 31: Model 720 (Onan Engine)

    ENGINE WILL CRANK, BUT NOT START MODEL 720 NOTES: Steering levers (Onan engine) 1. All tests are made with wires in out and PTO place on their respective switch 'OFF'. switches. Voltage tests 2. Refer to fuse block diagram for are performed terminal locations.

  • Page 32: Model 721 And 725 (Kubota Gasoline Engines)

    ENGINE WILL CRANK, BUT NOT START MODEL 721 and 725 NOTES: Steering levers (Kubota gasoline engines) 1. All tests are made with wires in out and PTO place on their respective switch 'OFF'. switches. Voltage tests 2. Refer to fuse block diagram for are performed terminal locations.

  • Page 33: Model 718D And 721D (Kubota Diesel Engines)

    ENGINE WILL CRANK, BUT NOT START MODEL 718D and 721D NOTES: Steering levers (Kubota diesel engines) 1. All tests are made with wires in out, PTO switch place on their respective 'OFF'. Voltage switches. tests are 2. Refer to fuse block diagram for performed with a voltmeter or terminal locations.

  • Page 34: Engine Starts, But Dies

    ENGINE STARTS, BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED MODELS 612, 614, 616 and 718 NOTES: Parking brake If the engine will crank and 'OFF'. Remove start, both steering switches, plug from back PTO switch and the seat switch of brake switch.

  • Page 35: Model 718K And 720K

    ENGINE STARTS, BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED MODELS 718K and 720K NOTES: Parking brake If the engine will crank and 'OFF'. Remove start, both steering switches, plug from back of PTO switch and the seat switch brake switch.

  • Page 36: Model 720 (Onan Engine)

    ENGINE STARTS, BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED MODEL 720 NOTES: Parking brake (Onan engine) If the engine will crank and 'OFF', operator start, control relay A and control 'OFF' seat, all relay B cannot be the problem.

  • Page 37: Model 718D, 721, 721D And 725 (All Kubota Engines)

    ENGINE STARTS, BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED MODEL 718D, 721, 721D and 725 NOTES: Parking brake (All Kubota engines) If the engine will crank and 'OFF', operator start, control relay A and control 'OFF' seat, all relay B cannot be the problem.

  • Page 38: Engine Starts, But Dies When Key Switch Is Released

    ENGINE STARTS, BUT DIES WHEN KEY SWITCH IS RELEASED MODEL 718D and 721D Steering levers (Kubota diesel engines) out, PTO switch 'OFF' and parking brake 'OFF'. Voltage tests are performed with a voltmeter or test light to battery ground. Key switch is in 'RUN' position for each test.
  • Page 39 ENGINE STARTS, BUT DIES WHEN KEY SWITCH IS RELEASED MODEL 718D and 721D NOTES: (Kubota diesel engines) 1. All tests are made with wires in place on their respective switches. 2. Problem is in the 'HOLD' circuit of the fuel solenoid. 3.

  • Page 40: Troubleshooting Pto Clutch

    TROUBLESHOOTING PTO CLUTCH Steering levers MODEL 612, 614, 616, 718, NOTES: out and PTO 718K and 720K 1. To see the wiring diagram for switch 'ON'. models with serial numbers of Voltage tests are performed 340725 and higher, refer to with a voltmeter figure 44 on page 44.

  • Page 41: Model 718D, 720, 721, 721D And 725

    TROUBLESHOOTING PTO CLUTCH MODEL 718D, 720, 721, 721D, NOTES: Steering levers and 725 1. If engine starts and runs, relay out and PTO 'A' is working properly. switch 'ON'. 2. To see the wiring diagram for Voltage tests models with serial numbers of...

  • Page 42: 1994 Model Updates

    1994 SUPPLEMENT MODEL 612 and 616 - Starting Circuit. (Briggs & Stratton engines) Serial numbers of 340725 and higher, refer to page 18 for troubleshooting. LEFT RI GHT SEAT BRAKE SWI TCH STEER SWI TCH STEER SWI TCH SWI TCH IN START POSITION STEERING LEVERS OUT PTO OFF...
  • Page 43 1994 SUPPLEMENT MODEL 718K and 720K - Starting Circuit. (Kohler Command engines) Serial numbers of 340725 and higher, refer to page 24 for troubleshooting. SEAT LEFT RI GHT SWI TCH SWI TCH SWI TCH STEER STEER PTO OFF STEERING LEVERS OUT IN START POSITION DRIVER ON SEAT...
  • Page 44 1994 SUPPLEMENT MODEL 612, 616, 718K and 720K - Clutch Circuit. Serial numbers of 340725 and higher, refer to page 40 for troubleshooting. SWI TCH SWI TCH IN RUN POSITION PTO ON CLUTCH FUSE Figure 44 MODEL 721, 721D and 725 - Clutch Circuit. Serial numbers of 340725 and higher, refer to page 41 for troubleshooting.

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