Grasshopper 718D Service Manual Download Page 3

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INTRODUCTION

SYMBOLS USED ON WIRING DIAGRAMS

SWITCH FUNCTIONS

6-7

TROUBLESHOOTING CONTROL RELAYS

Model 720, 721, and 725 ...........................................................................................

Model 718D and 721D...............................................................................................

Control relay - Model 720, 718D, 721, 721D, and 725 ..............................................

Circuit board diode problems - Model 720, 718D, 721, 721D, and 725.....................

FUSE BLOCK DIAGRAMS

TESTING SAFETY SYSTEM FOR PROPER OPERATION

Model 612, 614, 616, 718, 718K and 720K .............................................................

Model 720 (Onan), 718D, 721D, 721 and 725 ........................................................

BATTERY CHARGING SYSTEM

Model 718 (Briggs & Stratton Twin-II engine) ..........................................................

Model 612, 614, 616, and 718 (Briggs & Stratton Vanguard engines) and
Model 718K and 720K (Kohler Magnum & Command engines) ..............................

Model 720 (Onan engine) ........................................................................................

Model 718D, 721, 721D, and 725 (All Kubota engines) ..........................................

ENGINE WILL NOT CRANK

Model 612, 614, and 616 (Briggs & Stratton engines) ........................................

18-19

Model 718 (Briggs & Stratton Vanguard engines) ..............................................

20-21

Model 718K (Kohler Magnum engine) ................................................................

22-23

Model 718K and 720K (Kohler Command engines) ...........................................

24-25

Model 720 (Onan engine) ...................................................................................

26-27

Model 718D, 721, 721D, and 725 (All Kubota engines) .....................................

28-29

ENGINE WILL CRANK, BUT NOT START

Model 612, 614, 616, 718, 718K, and 720K (All engines) .......................................

Model 720 (Onan engine) ........................................................................................

Model 721 and 725 (Kubota gasoline engines) .......................................................

Model 718D and 721D (Kubota diesel engines) ......................................................

ENGINE STARTS, BUT DIES
WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED

Model 612, 614, 616 and 718 ..................................................................................

Model 718K and 720K .............................................................................................

Model 720 (Onan engine) ........................................................................................

Model 718D, 721, 721D, and 725 (All Kubota engines) ..........................................

(continued)

TABLE OF CONTENTS

Summary of Contents for 718D

Page 1: ...ridge Kansas 67107 U S A PHONE 620 345 8621 FAX 620 345 2301 PRICE 12 00 ALL MODELS WITH MODULAR WIRING SERIAL NUMBERS 310000 THROUGH 469999 Rev 01 95 Form 172110 Printed in U S A SERVICE MANUAL ELECTRICAL TROUBLESHOOTING VOLUME 1 ...

Page 2: ... bad terminals or wiring to that switch Consult the operator s manual wiring dia gram for the specific year and model of the machine you are working on for trouble shooting For further assistance contact The Grasshopper Company service depart ment at 620 345 8621 Copyright 1995 1994 1990 by The Grasshopper Company The following material is proprietary information All rights reserved Reproduction o...

Page 3: ... Model 720 Onan engine 15 Model 718D 721 721D and 725 All Kubota engines 16 ENGINE WILL NOT CRANK Model 612 614 and 616 Briggs Stratton engines 18 19 Model 718 Briggs Stratton Vanguard engines 20 21 Model 718K Kohler Magnum engine 22 23 Model 718K and 720K Kohler Command engines 24 25 Model 720 Onan engine 26 27 Model 718D 721 721D and 725 All Kubota engines 28 29 ENGINE WILL CRANK BUT NOT START M...

Page 4: ...IES 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 TABLE OF CONTENTS ...

Page 5: ... 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 Symbol for glass type fuse Symbol for automotive type fuse The number in the center of the fuse indicates the amperage rating of the fuse Indicates wires are spliced 0 0 ...

Page 6: ...C Accessory terminal 17 Glow plug terminal Diesel only 19 Glow plug indicator terminal Diesel only Brake switch part no 183894 NC normally closed means that the contact is closed and current will flow between these two terminals When the button is depressed these two terminals become open NO normally open means that the contact is open with the switch mechanism released When the button is depresse...

Page 7: ... is depressed The dotted line indicates an electrical con nection between the two terminal posts PTO switch part no 184082 The dotted line indicates an electrical con nection between the two terminal posts PTO switch part no 183925 The dotted line indicates an electrical con nection between the two terminal posts Seat switch part no 183870 The dotted line indicates an electrical con nection betwee...

Page 8: ...wire in the relay socket 2 Assuming the main fuse PTO fuse ignition fuse are good failure of control relay A or associated wiring will be evidenced by the following three symp toms A PTO clutch will not engage B Hourmeter will not run C Fuel solenoid will pull in but not hold 3 Assuming the start fuse is good failure of control relay B or associated wiring will result in starter solenoid not engag...

Page 9: ...seat switch Circuit Board Diode Problems Model 720 718D 721 721D and 725 Refer to the illustration below to locate the diode on the circuit board between pad R and A Open Diode An open diode will result in the following symptoms Assuming steering levers out and PTO switch off engine can be cranked and started only with driver on the seat and the parking brake in the OFF position If driver gets off...

Page 10: ... the two terminal posts MODELS 612 614 616 718 718K and 720K The dotted line indicates an electrical connection between the two terminal posts FUSE BLOCK DIAGRAMS Figure 3 Figure 4 LIGHT PTO START REG 30 7 5 7 5 7 5 A B C E G D F H PTO 7 5 7 5 REG 30 15 MAIN 30 IGN START A D E G F J B C I H ...

Page 11: ...ust or replace right steering switch Replace PTO switch Steering levers out PTO switch OFF operator ON seat parking brake ON and engine running Does engine die when steering levers are pulled in Replace brake switch No No No No No Yes Yes Yes Yes Yes Yes No MODEL612 614 616 718 718K 720K TESTING SAFETY SYSTEM FOR PROPER OPERATION Notes Proper operation of the safety system indicates that 1 Tostart...

Page 12: ...d engine running Does engine die when operator raises up off the seat Replace seat switch All safety systems are functioning properly Yes MODEL 720 Onan 718D 721D 721 and 725 TESTING SAFETY SYSTEM FOR PROPER OPERATION Notes Proper operation of the safety system indicates that 1 To start the engine both steering levers must be out and the PTO switch must be off The engine will start with the operat...

Page 13: ...Charging system is functioning properly Check for continuity of in line diode wire Check for shorted wires No No No Notes 1 Voltage tests are performed with a DC AC voltmeter 2 Tests are performed after regulator fuse is checked 3 AC voltage tests are performed with engine at 3600 rpm MODEL 718 Briggs Stratton Twin II engine BATTERY CHARGING SYSTEM voltage may vary depending upon RPM a properly fu...

Page 14: ... read voltage Does voltage read less than 28 volts AC with engine running If AC voltage measures more than 28 volts replace regulator rectifier For more detailed testing consult the engine repair manual Battery is in good condition Charging system is functioning properly Service stator Notes 1 Voltage tests are performed with a DC AC voltmeter 2 Tests are performed after regulator fuse is checked ...

Page 15: ... at full throttle Is voltage at battery between 13 and 14 7 volts Disconnect regulator rectifier plug Place AC voltmeter across AC terminals in plug and read voltage Does voltage read less than 41 volts AC at 3600 rpm Replace regulator rectifier For more detailed testing consult the engine repair manual Notes 1 Voltage tests are performed with a DC AC voltmeter 2 Tests are performed after regulato...

Page 16: ...blue wires from alternator A 10 volts AC at idle B 36 volts AC at full throttle Replace alternator No No Yes Does green wire on the regulator plug between the two blue wires show ground when tested to battery positive Check ground connection Check white wire and terminals rom terminal AC of ignition switch to voltage regulator No Yes Yes No Yes Yes Is voltage at red wire of voltage regulator 13 14...

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Page 18: ...e at terminal D of start fuse there should also be voltage on blue wire at starter solenoid continues on next page A MODEL 612 614 and 616 Briggs Stratton engines ENGINE WILL NOT CRANK Figure 5 Figure 6 NOTES 1 To see the wiring diagram for models with serial numbers of 340725 and higher refer to figure 40 on page 42 IN START POSITION PTO OFF STEERING LEVERS OUT R D B U Y E G R SEAT M B S G L NO N...

Page 19: ...ted Replace seat switch No Check starter solenoid Problem could be starter solenoid or starter Do both wires on RT steering switch show ground when tested Do either of the RT steering switch wires show ground Replace PTO switch Do both wires on LT steering switch show ground when tested LT steering switch is bad or out of adjustment RT steering switch is bad or out of adjustment Recheck starter so...

Page 20: ...e If there is voltage at terminal D of start fuse there should also be voltage on blue wire at starter solenoid MODEL 718 Briggs Stratton Twin II and Vanguard engines ENGINE WILL NOT CRANK Figure 8 Figure 9 NOTES 1 To see the wiring diagram for models with serial numbers of 340725 and higher refer to figure 41 on page 42 IN START POSITION PTO OFF STEERING LEVERS OUT R D B U B U Y E G R SEAT NO NC ...

Page 21: ...t switch Check starter solenoid Problem could be starter solenoid or starter Do both wires on LT steering switch show ground when tested Do either of the LT steering switch wires show ground Replace PTO switch No Do both wires on RT steering switch show ground when tested RT steering switch is bad or out of adjustment LT steering switch is bad or out of adjustment Yes No Yes Recheck starter soleno...

Page 22: ... Does voltage appear from terminal D of start fuse Replace start fuse If there is voltage at terminal D of start fuse there should also be voltage on blue wire at starter solenoid MODEL 718K Kohler Magnum engines ENGINE WILL NOT CRANK Figure 11 Figure 12 LIGHT PTO START REG 30 7 5 7 5 7 5 A B C E G D F H IN START POSITION PTO OFF STEERING LEVERS OUT R D B U B U Y E G R SEAT NO NC DIODE ALLOWS ENGI...

Page 23: ...ter solenoid Problem could be starter solenoid or starter Do both wires on LT steering switch show ground when tested LT steering switch is bad or out of adjustment Does seat switch show ground on both yellow wires Note Wires must be installed on switch and seat switch must be activated Both wires show ground Replace starter relay Only one wire shows ground Replace seat switch Neither wire shows g...

Page 24: ...nal 87 of starter relay Check in line fuse in wire coming from the starter Yes No Yes Check starter solenoid Problem could be starter solenoid or starter Does voltage appear on terminal 30 of starter relay No Yes ENGINE WILL NOT CRANK Figure 14 MODEL 718K and 720K Kohler Command engines Figure 16 Figure 15 NOTES 1 To see the wiring diagram for models with serial numbers of 340725 and higher refer ...

Page 25: ...oth yellow wires Note Wires must be installed on switch and seat switch must be activated Only one wire shows ground Replace seat switch Neither wire shows ground Replace PTO switch MODEL 718K and 720K Kohler Command engines ENGINE WILL NOT CRANK Figure 17 Note Plug starter relay back in when finished testing 30 Fuse holder To input terminal of starter To pad T of circuit board To pad S of circuit...

Page 26: ... is the key switch or the power to the key switch No Check starter solenoid Problem could be starter solenoid or starter Does voltage appear from terminal I of start fuse to ground Replace start fuse No Yes Does yellow wire in terminal 86 of control relay B show ground when tested Do both wires on LT steering switch show ground when tested LT steering switch is bad or out of adjustment No Replace ...

Page 27: ...igure 20 Figure 18 BU YE YE YE BU BU RD GR BU R A B STARTER I S IN START POSITION PTO OFF STEERING LEVERS OUT START FUSE RELAY B PTO SWITCH LEFT STEER RIGHT STEER KEY SWITCH LT STR RT STR 87 86 85 30 PTO 7 5 7 5 REG 30 15 MAIN 30 IGN START A D E G F J B C I H ...

Page 28: ... switch Does voltage appear from terminal J of start fuse Replace start fuse Does voltage appear on blue wire at starter solenoid No Yes Check starter solenoid Problem could be starter solenoid or starter MODEL 718D 721 721D and 725 All Kubota engines ENGINE WILL NOT CRANK Figure 21 NOTES 1 To see the wiring diagram for models with serial numbers of 340725 and higher refer to figure 43 on page 43 ...

Page 29: ...teering switch check adjustment If it does not click when steering levers are moved in and out adjust switch Replace left steering switch continued A Replace relay B Do both yellow wires on right steering switch test grounded Before replacing steering switch check adjustment If it does not click when steering levers are moved in and out adjust switch Replace right steering switch Replace PTO switc...

Page 30: ...g properly Disconnect yellow wire from engine and test Does spark occur at spark plug This is an engine related problem Consult engine repair manual Interlock module or associated wiring is defective MODEL 612 614 616 718 718K and 720K All engines ENGINE WILL CRANK BUT NOT START ...

Page 31: ... fuse Replace key switch Does yellow wire in terminal 85 of control relay A show ground Check yellow wire to pad R or diode from pad A to pad R Replace control relay A No No No Yes No Yes No Yes MODEL 720 Onan engine NOTES 1 All tests are made with wires in place on their respective switches 2 Refer to fuse block diagram for terminal locations 3 Refer to Troubleshooting Control Relays for informat...

Page 32: ...eplace ignition fuse Does voltage appear from terminal B of main fuse to ground Replace main fuse Replace key switch MODEL 721 and 725 Kubota gasoline engines ENGINE WILL CRANK BUT NOT START NOTES 1 All tests are made with wires in place on their respective switches 2 Refer to fuse block diagram for terminal locations 3 Refer to Troubleshooting Control Relays for information on the diode and contr...

Page 33: ...o COMM terminal of fuel solenoid Replace fuel solenoid Fuel solenoid linkage is binding or sticking MODEL 718D and 721D Kubota diesel engines NOTES 1 All tests are made with wires in place on their respective switches 2 Refer to fuse block diagram for terminal locations 3 Refer to Troubleshooting Control Relays for information on the diode and control relays 4 If engine will crank control relay B ...

Page 34: ... Does yellow wire on brake switch show ground when tested Replace parking brake switch Replace interlock module ENGINE STARTS BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED MODELS 612 614 616 and 718 NOTES If the engine will crank and start both steering switches PTO switch and the seat switch are functioning properly The problem must be the brake switch or the interlock module Green...

Page 35: ...ctioning properly The problem must be the brake switch or the interlock module Yellow Yellow Brake switch view Figure 32 NC NO No Yes Replace interlock module Parking brake OFF Remove plug from back of brake switch With an ohm meter test through the brake switch on the posts that were connected to the two yellow wires figure 32 Does brake switch read closed circuit 0 ohms Replace parking brake swi...

Page 36: ...re 33 Replace parking brake switch Replace seat switch ENGINE STARTS BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED MODEL 720 Onan engine Green Yellow Brake switch view Figure 33 NOTES If the engine will crank and start control relay A and control relay B cannot be the problem The PTO switch the left steer ing switch and the right steer ing switch cannot be the prob lem Therefore the...

Page 37: ...ed figure 34 Replace parking brake switch MODEL 718D 721 721D and 725 All Kubota engines ENGINE STARTS BUT DIES WHEN LEVERS ARE BROUGHT IN OR PTO SWITCH IS ENGAGED Green Yellow Brake switch view Figure 34 NOTES If the engine will crank and start control relay A and control relay B cannot be the problem The PTO switch the left steer ing switch and the right steer ing switch cannot be the prob lem T...

Page 38: ...he key switch Does voltage appear from terminal 1 of fuel solenoid module figure 35 to ground Does voltage appear from terminal G of ignition fuse to ground Replace control relay A This is the relay with 2 red 1 yellow and 1 black wire Does voltage appear from terminal 2 of fuel solenoid module to battery positive Repair ground Replace ignition fuse No No Yes Yes Yes continues on next page A MODEL...

Page 39: ...3 COM M RELAY A PULL TO SAFETY SWITCHES W H G R B K STARTER Battery Cable FUEL SOLENOID FUEL SOLENOID MODULE IGNITION FUSE MAIN FUSE KEY SWITCH R D R D R D R D R D B K B K B K B K IN LINE FUSEHOLDER Yes No No Yes continued A Does voltage appear from HOLD wire of fuel solenoid to ground Check fuel solenoid plug connection Does voltage appear from terminal 4 of fuel solenoid module to ground Replace...

Page 40: ...ug to ground Replace PTO switch Does green wire of PTO clutch show ground Test ground connections on clutch No Test PTO clutch and terminals Verify air gap of 012 on electric clutch see owner s manual Test clutch by reading ohm s across clutch plug plug disconnected Resistance should measure approximately 2 3 to 2 7 ohms TROUBLESHOOTING PTO CLUTCH MODEL 612 614 616 718 718K and 720K Figure 39 Figu...

Page 41: ...lutch and terminals Verify air gap of 012 on electric clutch see owner s manual Test clutch by reading ohm s across clutch plug plug disconnected Resistance should measure approximately 2 3 to 2 7 ohms MODEL 718D 720 721 721D and 725 TROUBLESHOOTING PTO CLUTCH Figure 40 Figure 41 NOTES 1 If engine starts and runs relay A is working properly 2 To see the wiring diagram for models with serial number...

Page 42: ... Circuit Briggs Stratton engines Serial numbers of 340725 and higher refer to page 18 for troubleshooting Figure 41 MODEL 718 Starting Circuit Briggs Stratton Vanguard engines Serial numbers of 340725 and higher refer to page 20 for troubleshooting IN START POSITION PTO OFF STEERING LEVERS OUT R D B U B U Y E G R SEAT NO NC DIODE ALLOWS ENGINE TO CRANK WITH BRAKE SWITCH ON OR OFF KEY SWITCH DRIVER...

Page 43: ...K WITH BRAKE SWITCH ON OR OFF KEY SWITCH LT STR RT STR DRIVER ON SEAT SEAT SWITCH Y E Y E Y E Y E M B S G L Figure 43 MODEL 721 721D and 725 Starting Circuit All Kubota engines AC 50 19 30 17 BU YE RD GR STARTER IN START POSITION PTO OFF STEERING LEVERS OUT START FUSE RELAY B PTO SWITCH LEFT STEER RIGHT STEER KEY SWITCH LT STR RT STR YE YE BU BU BU Serial numbers of 340725 and higher refer to page...

Page 44: ...utch Circuit Serial numbers of 340725 and higher refer to page 40 for troubleshooting Figure 45 PTO FUSE TO SAFETY SWITCHES RELAY A CLUTCH RD IN RUN POSITION PTO SWITCH KEY SWITCH BK BR GR MAIN FUSE PTO ON RD RD RD YE BR 17 30 19 50 AC MODEL 721 721D and 725 Clutch Circuit Serial numbers of 340725 and higher refer to page 41 for troubleshooting ...

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