Ryobi RY48ZTR75 Service Manual page 46

TESTING RELAY
NEG
(-)
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1. Power Mower ON.
2. Set DMM to "DC Volts".
3. Check for 12V on the small terminals (under the black caps).
4. Check for approximately 39+V on the large terminals (under
the red caps).
Alternate method to test relay
POS
independent of mower:
(+)
1. Unbolt one leg of diode if equipped.
2. Set DMM to measure Resistance.
3. Connect DMM to large terminals.
4. Apply 12V to small terminals.
5. You should hear a click as the relay switch Is activated,
and measure small resistance at relay terminals
Nominal resistance 1.5 Ohms