Ryobi RY48ZTR75 User manual

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SERVICE CENTER ELECTRICAL SYSTEM TROUBLESHOOTING AND TESTING GUIDE
RYOBI RY48ZTR75/100 AND RY48140 RIDING MOWER

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TABLE OF CONTENTS
•WARNING
•ZTR Mower Overview
•Brushless Motors
•Using this Manual
•ZTR Block Diagram and Control Flow
•Troubleshooting: General
•Troubleshooting: Detailed
•DMM and Other Tools
•Component Locations
•Controller and Label Locations
•Main Battery Connection
•Testing Main Fuse
•Testing Battery Voltage
•Control Panel
•Testing PTO Switch
•Testing Headlight Switch
•Testing the Drive Speed Switch
•Testing Blade Cutting Speed Switch
•Testing Fuel Gauge / Hour Meter
•Testing Key Switch
•Testing USB Port
•Testing the Neutral “Zero” Switches
•Testing Headlight Assembly
•Testing Accelerator (angular transducers)
•Testing Brake Switch
•Testing Beeper
•Testing Seat Switch
•Testing Primary Blade Motor Controller
•Testing Secondary Blade Motor Controller
•Testing Drive Motor Controllers
•Testing Blade Motors
•Testing Drive Motors
•Testing Drive Motor Hall Sensors
•Testing 48V-12V Converter and fuse
•Testing Relay
•Testing Relay Diode
•Testing Charge port and interlock
•Testing the Battery Charger
•Battery Charger Error Codes
•ZTR Beep Codes
•Testing the Temperature Sensor
•Wire Harness
•Pre and Post-Repair Checklist
•Electronic Tips for the Mechanical Small Engine Tech
•Electronics Terms, Symbols and Tools
•Using the Digital Multi-Meter (DMM)

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WARNING
THIS MATERIAL INTENDED ONLY FOR TECHNICIANS TRAINED IN ELECTRICAL REPAIR.
Technicians should wear personal protective equipment, such as rubber
gloves and safety glasses.
Dangerous voltages /currents are present. Exercise caution at all times.
This manual assumes knowledge of basic electrical equipment such as DMM (Digital Multi Meter)
and clamping Amp Meter to measure voltage, current, resistance, continuity, and diodes.

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The RYOBI ZTR riding mower is completely electrical, consisting of 4brushless
motors and acontroller for each motor:
•Abrushless motor and controller for each of the 2blades
•Abrushless motor/controller to drive each rear wheel.These Drive Motor Controllers
also contains the “brains” that responds to various inputs such as the accelerators,
seat switch,etc.
OVERVIEW

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Brushless motors operate quite differently than brushed motors, which you may be
used to (i.e. a starter motor).
Abrushed motor can be quickly tested by applying voltage to the two terminals.
Brushless motors can be recognized by 3wires. These 3wires require a controller to
operate them and to turn on these 3 phases in a precise fashion similar to spark plugs
firing a 3-cylinder gas motor.
Applying avoltage directly to these phases will cause damage.
BRUSHLESS MOTORS

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Any blue text can be clicked on to jump directly to the page of that topic. (This document
is also printer-friendly, so you can have it in front of you while servicing the mower.) If
you print this document, we recommend printing it in landscape mode and in color
ABlock Diagram shows the general flow to visualize how the mower is connected and
achart shows general symptoms/solutions for repairs.
Electronics tips ,Terminology and Using a Digital Multi-Meter (DMM) are included for
the technician familiar only with gas machines.
USING THIS DOCUMENT

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TOOLS NEEDED
Torx
T27
T30
T40
Screwdrivers
Cross tip
Flat blade
Sockets and
Wrenches
8 mm
10 mm
13 mm
14 mm
15 mm
17 mm
19 mm

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48V
Batteries
Main Fuse
Charge
Port/lockout/
battery temp
48V to 12V
(DC to DC)
converter
Relay
Fuel
Gauge
Brake
Switch
Beeper
Seat
switch
Fuse
Primary
Blade
Control
Secondary
Blade
Control
Motor Motor
Head
Lights
Accelerator
Note: A detailed wire harness diagram is
located later in this document
USB
Important:Primary and secondary
have a communication link. If one
blade motor or controller fails,
BOTH will shut down.
48V
Secondary
Drive
Controller
Accelerator
PTO
Drive Speed
Switch
Blade
Speed
Key
Switch
12V
Left
Neutral
switch
5V out
Motor
Hall Sensors
Primary
Drive
Controller
Motor
Hall Sensors
RIGHT
Neutral
switch
Enables
BLOCK DIAGRAM AND CONTROL FLOW

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•Follow the Block Diagram on the previous page.
•Check for loose/bad connections.
•Test the easiest components first. (power, key switch, DC-DC converter)
•Mower should be fully charged (if possible)
•Before disassembly:
–Attempt to charge mower (note any error LED indications)
–Check for voltage at charge port.
–Check USB Indicator and Headlights are functional (this tests the 48V-12V converter)
•Remove Instrument Panel cover
–Test Key Switch
–Check all other connections while panel is removed.
TROUBLESHOOTING: GENERAL

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Use the block diagram as aguide
Also refer to the beep diagnostic code chart
1. Verify the battery charger is functional by plugging it into the charge port on the back of the mower and let the mower fully
charge.
2. If necessary, further test the charger and charge port.Replace as needed.Charge port,Interlock, and temperature sensor
should be replaced together.
3. Test the key switch by operating it, making sure it has atactile “click” when turned on or off. Replace if necessary
4. Test and replace main relay and diode as necessary. (Note: when you turn the mower on, you should hear the relay click)
5. Check the main fuse.If it is blown, check the system for signs of ashort circuit before replacing the main fuse
6. If the fuel gauge has power, but no display or malfunctions, replace the fuel gauge
7. If ONLY the fuel gage works when the key is turned on, test/replace the 48-to-12V DC converter and 5A fuse as
necessary Note: this fuse is acommon part available at any automotive store
TROUBLESHOOTING: DETAILED

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8. If the mower will not drive
a. Make sure the seat switch is functional and activated.
b. Test the angular transducers.Replace if necessary.
c. Test the neutral switches.Replace if necessary.
d. Test the brake switch.Replace if necessary.
e. If the mower still will not drive, test the Drive Motor controllers.Replace if necessary.
f. Test the drive motors and Hall sensors,replace as necessary
9. Test the blade operation by pulling up on the PTO switch
a. Make sure the seat switch is functional and activated.
b. Test the primary and secondary motors.Replace as a pair if found bad
c. Test the primary blade and secondary blade controllers.Replace as apair if found bad.
d. If the mower blades still will not operate, replace the Drive motor controllers (same as step 8e above)
10. If the mower works except for the headlights, test the headlight switch and headlights.Replace as necessary
TROUBLESHOOTING: DETAILED CONTINUED

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Typical DMM (Fluke 87). Note the dial is set to the
“DIODE” function.
this function will be used in
many of the following procedures.
Also note where the red and black jacks
of the test leads are connected to the DMM.
If you are unfamiliar with aDMM, please read the section
Electronics Tips for the Mechanical Small Engine Technician
DIGITAL MULTIMETER (DMM)

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Brake Switch
Headlights
Seat
Switch
Beeper
Controllers
DC-DC
converter
Charge port
Neutral “zero”
Switches
Accelerator
transducers
COMPONENT LOCATIONS
Access panel
(under seat)

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“Deck Motor Controller” “Drive Motor Controller 2” “Drive Motor Controller”
(Shown with passenger leg panel removed)
As a note the
RY48140 will
have 3 deck
motor controllers
with 2 being
Secondary and
1 as a Primary
CONTROLLERS AND LABEL LOCATIONS
“Deck Motor Controller”

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The main battery disconnect is located directly under the seat
access cover. It may take considerable pressure to separate the
halves.
If you can not separate by hand, you may need a blunt instrument
to push in the hole in the direction indicated.
NOTE THAT ONE HALF OF THE CONNECTOR IS
SCREWED TO THE FRAME AND WILL NOT MOVE.
BE CAREFUL NOT TO DAMAGE THE CONNECTOR.
MAIN BATTERY CONNECTION

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IMPORTANT: If the main fuse is blown, find
the source of problem before replacing fuse
Where probes go
1.Disconnect main battery connection
2. Open the plastic box to access main fuse.
3. Set DMM to Resistance Ωsymbol on DMM
•Measure were indicated to the left.
•Ensure the nuts are tight, but not
•overtightened, as this can cause the fuse
•to twist and break.
If fuse is blown,
Replace only with the same physical size and same
Amperage.
MAIN FUSE

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Two Different Charging Ports
The Charging port on the Left is the Gen 1
charger.
The Charging port on the Right is the Gen 2
charger.
Note the Different
indexing plugs.
Make sure when
ordering charging
port or charger
they are the same
type.
CHARGING PORT

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Charge Indicator LED (LED should blink in
similar pattern to charger when charger is
connected)
Charger Interlock
Note: New mowers have a different
pattern of Indexing pin. When requesting
repair parts, send a picture of this
connector to ensure proper parts
For the charger and charge port
Note: If a valid voltage cannot be
read, the electronics built into the
charge port may be bad. In this
event, find the blue connector
which connects directly to the
batteries. Disconnect it, and
measure battery voltage
1. Set DMM to “DC Volt” mode.
2. Turn mower on.
3. Pull PTO switch up (Power Take Off/Blade Engage knob) to load the battery for
more accurate measurement.
4. Place RED DMM probes indicated by red arrow, BLACK probe by black arrow
BATTERY VOLTAGE TEST

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Many of the connectors are sealed together with heat shrink tubing. To separate the connectors, soften the heat
shrink with a heat gun, then peel the heat shrink tubing off with pliers as shown.
Connector
Heat
Gun
Connector
When reassembling connectors, be sure to apply new heat shrink tubing and shrink with a heat gun to
protect against elements and hold the connections together.
Extra care is needed to avoid damaging surrounding parts by the heat. Be careful of the batteries.
SEPARATING CONNECTORS

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CONTROL PANEL
PTO
(Power Take Off)
Low Speed Button
Main Power Key Switch
Fuel Gauge/ Hour Meter
Headlight switch
Low Speed Cut Button
USB Charger