4-48 673831-Rev A
ELECTRICAL
4
Mow/Backlap Circuits
Symptom: Mow solenoids do not energize.
Symptom: Backlap solenoids do not energize.
Symptom: Four wheel drive solenoid does not energize (4WD Option Only).
Probable Cause Remedy
Engine in overheat condition. Mow solenoids (SOL1 and SOL2) will not energize if engine temperature is above 230° F
(110° C). Allow the engine to cool and check the engine cooling system.
Faulty mow switch. Test mow switch (SW2). (See “Mow Switch Test” on page 4-55.)
Faulty lift proximity switch. Test lift proximity switch (SW8). (See “Proximity Switches Test” on page 4-57.)
Faulty front and rear mow solenoid. Test mow solenoids (SOL1 and SOL2). (See “Solenoids Test” on page 4-59.)
Faulty wire harness. Measure continuity between the mow switch (SW2) terminal 3 and MCU terminal 4-09.
Continuity must be indicated. Make certain the set speed jumper connector is firmly
attached to the harness connector.
Measure continuity between the lift proximity switch (SW8) and MCU (U1) terminal 4-02.
Continuity must be indicated.
Measure continuity between the MCU (U1) terminal 5-02 and the front and rear mow
solenoids (SOL1 and SOL2). Continuity must be indicated.
Measure continuity between ground and the front and rear mow solenoids (SOL1 and
SOL2) ground terminal. Continuity must be indicated.
Faulty MCU Replace the MCU
Probable Cause Remedy
Engine in overheat condition. Backlap solenoids (SOL3 and SOL4) will not energize if engine temperature is above
230° F (110° C). Allow the engine to cool and check the engine cooling system.
Faulty lift proximity switch. Test the lift proximity switch (SW8). (See “Proximity Switches Test” on page 4-57.)
Faulty parking brake switch. Test the parking brake switch (SW5). (See “Parking Brake Switch Test” on page 4-56.)
Faulty neutral switch. Test the neutral switch (SW7). (See “Proximity Switches Test” on page 4-57.)
Faulty front and rear backlap solenoid. Test the backlap solenoids (SOL3 and SOL4). (See “Solenoids Test” on page 4-59.)
Faulty wire harness. Measure continuity between the mow switch (SW2) terminal 3 and MCU (U1) terminal
4-09. Continuity must be indicated. Make certain the set speed jumper connector is
firmly attached to the harness connector.
Measure continuity between the lift proximity switch (SW8) and MCU (U1) terminal 4-02.
Continuity must be indicated.
Measure continuity between the MCU (U1) terminal 6-03 and the front and rear backlap
solenoids (SOL3 and SOL4). Continuity must be indicated.
Measure continuity between ground and the front and rear backlap solenoids (SOL3 and
SOL4) ground terminal. Continuity must be indicated.
Faulty MCU Replace the MCU
Probable Cause Remedy
Faulty 4WD solenoid. Test 4WD solenoid (SOL7). (See “Solenoids Test” on page 4-59.)
Faulty 4WD relay Test 4WD relay (K5). (See “Relays Test” on page 4-53.)
Faulty wire harness. Measure continuity between the MCU (U1) terminal 5-07 and the 4WD relay (K5) terminal
86. Continuity must be indicated.
Measure continuity between the 4WD relay (K5) terminal 87 and 4WD solenoid (SOL7).
Continuity must be indicated.
Measure continuity between ground and the 4WD solenoid ground terminal. Continuity
must be indicated.
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