Travel FailureLowering FailureCharging Diagnosis24V System Check
Summary
This technician guide provides a structured diagnostic and repair process for the
A-103701 electric pallet jack. It focuses on three common service conditions:
the pallet jack cannot move, the forks cannot lower, and the unit cannot charge normally.
The guide helps technicians isolate likely causes step by step, including sensor faults,
brake issues, motor voltage output, controller terminal wiring, solenoid valve response,
lower button continuity, battery voltage, and charger output.
1
Unable to Move
Start with a basic functional check, then isolate the fault through the sensor, brake,
motor voltage, and controller terminal wiring.
Step 1: Initial Function Check
Turn on the power and verify whether the lifting and horn functions work properly.
Check the display panel for error codes. If an error code is shown, record it before further service.
If both travel and lifting functions fail, the controller is likely faulty and may need replacement.
Initial function and display check
Step 2: No Error Code & Normal Lifting Function
Press and hold the Turtle button, then press the accelerator.
If the pallet jack moves, the sensor requires replacement.
Turtle button and sensor test
Step 3: Check the Brake
Repeat the operation and listen for a “click” sound from the brake when pressing the handle and accelerator.
If the click is heard, remove the brake and hang it on the jack body.
Attempt to move again. If the pallet jack moves successfully, the brake needs replacement.
Brake inspection and removal
Step 4: Test Motor Voltage
Use a multimeter to measure voltage across the motor wires while pressing the accelerator.
When the accelerator is fully pressed, approximately 24VDC is expected.
Voltage presentThe motor requires replacement.
No voltageContinue to controller terminal wiring inspection.
Measure motor voltageMotor wire voltage check
Step 5: Inspect Controller Terminals and Wiring
Measure voltage at controller terminals M1 and M2 while pressing the accelerator.
When fully pressed, approximately 24VDC is expected.
Voltage presentCheck the M1 and M2 wiring harness for continuity.
No voltageThe handle rudder likely needs replacement.
Controller M1/M2 voltage testController wiring inspection
2
Unable to Lower
If the unit can lift but cannot lower, start from the solenoid valve, then continue through
bottom linkage, lower button continuity, controller A11 voltage, and wiring continuity.
Step 1: Check Solenoid Valve Magnetism
Open the cover and remove the solenoid valve nut.
While pressing and holding the “Lower” button, check whether the valve core has magnetism.
MagneticProceed to bottom linkage inspection.
Not magneticMeasure solenoid valve voltage.
Check solenoid valve magnetism
Step 2: Inspect Bottom Linkage
If the solenoid valve shows magnetism, inspect the bottom linkage for excessive lifting or deformation.
Tilt the truck or gently tap the fork wheels forward if better visibility is needed.
If the linkage appears normal, the hydraulic pump may be faulty.
Bottom linkage inspection
Step 3: Measure Solenoid Valve Voltage
If the solenoid valve is not magnetic, set the multimeter to DC voltage.
Measure voltage across the two ends of the solenoid valve while pressing the “Lower” button.
Set the multimeter to DC voltage and measure between controller A11 and B-.
While pressing “Lower,” voltage should normally change from 24V to 0V.
No voltage changeThe controller needs replacement.
Voltage changes normallyProceed to A11-to-solenoid continuity test.
Controller A11 voltage test
Step 6: Test A11 Pin to Solenoid Valve Continuity
Measure continuity between the A11 pin on the controller and the A11 pin on the solenoid valve.
If there is no beep, the wiring harness needs replacement.
A11 pin to solenoid valve continuity test
3
Unable to Charge
Charging failures should be checked in order: connection sequence, charger indicator status,
connector pins, battery voltage, direct power delivery, and outlet voltage.
Step 1: Verify Charging Sequence
First connect the charger to the battery.
Then plug the charger into the power outlet.
Correct charger connection sequence
Step 2: Check Charger Status
Normal charging: red indicator light stays on and the charger fan spins.
If the pallet jack still will not power on, treat it as a total power loss issue.
Normal charger indicator and fan status
Step 3: Green Blinking Light / Abnormal Charging
Check whether connector pins are loose. Reinsert if needed.
If pins are secure, use a multimeter to test battery voltage. Battery voltage should be at least 10VDC.
Voltage normalReplace the charger.
Voltage lowContinue to the power delivery test.
Connector pin and battery voltage check
Step 4: Low Battery Voltage? Test Power Delivery
Disconnect the charger from the outlet.
Connect the charger directly to the pallet jack wiring harness, bypassing the battery.
Activate the emergency stop switch and key switch.
Plug the charger back into the outlet and observe whether the display lights up.
Screen ONReplace the battery.
Screen OFFConfirm the outlet delivers 110–120V. If it does, replace the charger.
Connect charger directly to wiring harnessTurn on emergency stop and key switchObserve whether display powers on
✓
Conclusion
Proper diagnosis and systematic repair are critical when servicing the
A-103701 electric pallet jack. By following the procedures above,
technicians can isolate travel, lowering, and charging faults more efficiently and reduce unnecessary downtime.
Verify System OutputConduct full functional testing and monitor diagnostic readings for at least 15 minutes after repair.
