Ryobi Homelite RY48ZTR75/100 User manual

Ryobi RY48ZTR75/100 Riding Mower
Electrical Components Troubleshooting and Testing
J.Davis 4-18-2019
Anderson, South Carolina

Table of Contents
•WARNING 3
•ZTR Mower Overview 4
•Brushless Motors 5
•Using this Manual 6
•ZTR Block Diagram and Control Flow 7
•Troubleshooting: General 8
•Troubleshooting: Detailed 9
•DMM and Other Tools 10
•Component Locations 12
•Controller and Label Locations 13
•Main Battery Connection 14
•Testing Main Fuse 15
•Testing Battery Voltage 16
•Control Panel 17
•Testing PTO Switch 18
•Testing Headlight Switch 19
•Testing the Drive Speed Switch 20
•Testing Blade Cutting Speed Switch 21
•Testing Fuel Gauge / Hour Meter 22
•Testing Key Switch 23
•Testing USB Port 24
•Testing the Neutral “Zero” Switches 25
2
•Testing Headlight Assembly 26
•Testing Accelerator (angular transducers) 27
•Testing Brake Switch 28
•Testing Beeper 29
•Testing Seat Switch 30
•Testing Master Blade Motor Controller 31
•Testing Slave Blade Motor Controller 32
•Testing Drive Motor Controllers 33
•Testing Blade Motors 34
•Testing Drive Motors 35
•Testing Drive Motor Hall Sensors 36
•Testing 48V-12V Converter and fuse 37
•Testing Relay 38
•Testing Relay Diode 39
•Testing Charge port and interlock 40
•Testing the Battery Charger 41
•Battery Charger Error Codes 44
•ZTR Beep Codes 45
•Testing the Temperature Sensor 46
•Wire Harness 47
•Pre and Post-Repair Checklist 48
•Electronic Tips for the Mechanical Small Engine Tech 49
•Electronics Terms, Symbols and Tools 50
•Using the Digital Multi-Meter (DMM) 51
•Revision Log

C
THIS MATERIAL INTENDED ONLY FOR TECHNICIANS TRAINED IN ELECTRICITY.
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)
to measure voltage, current, resistance, continuity, and diodes.
3
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ZTR Mower Overview
The Ryobi ZTR riding mower is completely electrical, consisting of 4 brushless
motors and a controller for each motor
for each motor:
•A brushless motor and controller for each of the 2 blades
•A brushless 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.
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Brushless Motors
Brushless motors operate quite differently than brushed motors, which you
may be used to (i.e. a starter motor).
A brushed motor can be quickly tested by applying voltage to the two
terminals.
Brushless motors can be recognized by 3wires. These 3 wires require a
controller to operate them and to “fire” these 3 phases in a precise fashion
similar to spark plugs firing a 3 cylinder gas motor. Applying a voltage directly
to these phases will cause damage.
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Using this Document
•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
•A Block Diagram shows the general flow to visualize how the mower is
connected and a chart 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.
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ZTR Block Diagram And Control Flow
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
Master
Blade
Control
Slave
Blade
Control
Motor Motor
Head
Lights
Accelerator
Note: A detailed wire harness diagram is
located later in this document
USB
Important: Master and slave have
a communication link. If one blade
motor or controller fails, BOTH will
shut down.
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48V
Slave
Drive
Controller
Accelerator
P
PTO
P
Drive Speed
Switch
P
Blade
Speed
Key
Switch
12V
Left
Neutral
switch
5V out
7
Motor
Hall Sensors
Master
Drive
Controller
Motor
Hall Sensors
RIGHT
Neutral
switch
Enable

Troubleshooting: General
•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.
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Troubleshooting: Detailed
Use the block diagram as a guide
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 a tactile “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 a short 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 a common part available at any automotive store
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 master and slave motors. Replace as a pair if found bad
c. Test the master blade and slave blade controllers. Replace as a pair 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
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Digital Multi Meter (DMM)
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 a DMM, please read the section
Electronics Tips for the Mechanical Small Engine Technician
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Other Helpful Tools and Parts
11
12V output
5V output
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Component Locations
12
Headlights
Seat
Switch
Beeper
DC-DC
converter Brake Switch
Accelerator
transducers
Access panel
(under seat)
Charge port
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Controllers
Neutral “zero”
Switches

Controllers and Label Locations
13
“Deck Motor Controller” “Drive Motor Controller 2” “Drive Motor Controller”
(Shown with passenger leg panel removed)
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Main Battery Connection
Main battery disconnect is located directly under the seat
access cover. It may takes 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.
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Testing Main Fuse
1. Disconnect main battery connection
2. Open the plastic box to access
main fuse.
3. Set DMM to Resistance
Measure where indicated below.
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 and Voltage.
15
IMPORTANT: If the main fuse is blown, find the source of problem before replacing fuse
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https://www.mouser.com/ProductDetail/Littelfuse/14256316122?qs=sGAEpiMZZMsh2y49K8ANrTdpOrToc%252bEOWEps5yIgKK0%3d
Available at Mouser.com:

Testing 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
Charge Indicator LED
Charger Interlock
16
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
Note: Some mowers have a different pattern of Indexing pin(s).
When requesting repair parts, send a picture of this connector to ensure proper parts
for the charger and charge port
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+
Approx 48V DC

Control Panel
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Power Switch
Headlights
Low/HighDrive Speed
Blade power Switch
(AKA “PTO” Switch
Low/High Blade Cutting Speed
Fuel Gauge
USB Charge Port

Testing PTO (Power Take Off) Switch
3. Insert DMM probes where indicated.
When red button is PULLED OUT, the
switch is CLOSED (very LOW resistance or
continuity) typically 0 Ohms
4. When red button is PUSHED IN, the
switch is OPEN (very HIGH resistance or
no continuity) typical 12K Ohms when in circuit or open
when removed from circuit.
Note: Make sure
spade lugs are
secure. They should
be locked in place
and should not come
loose if the wires are
pulled on.
Note: 3 terminals are not connected
1. Mower Power OFF
2. DMM set to measure
Resistance
18
5V
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Testing Headlight Switch
3. Touch leads where
indicated. LED should light
(polarity of probes does not
matter).
4. Set DMM to Resistance mode
This is a latching switch.
Pressing the button alternates between open
and closed switch.
1. Disconnect Main Power from Mower.
2. DMM set to “Diode” mode.
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Testing Drive Speed Switch
and Cutting Speed switch
•This test procedure is the same as the headlight switch
procedure. The only difference is these switches are
momentary.
•When the button is held in, the switch is closed.
•When the button is released, the switch is open.
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