Equalizer systems hydraulic pump troubleshooting

What it is

Equalizer Systems hydraulic pumps are 12 VDC. A solenoid, relays or a reversing contactor switch battery power to the motor. If the motor does not run, the fault is power, ground, the motor, the switching device, or the exciter signal from the control.

Before you diagnose

Read the pump number off the unit. The test method depends on the pump type.

Battery at about 12.5 VDC at the solenoid battery terminal.

Heavy ground cable from the port plate ground stud to battery or frame. Check the battery-to-frame connection.

Power and ground cables at least 4 gauge on the solenoid-type units.

Motor current|Up to 160 A at minimum 10.5 VDC (solenoid units)

Minimum exciter voltage|10.5 VDC on the blue or green wire during a command

Uni-directional pumps (one solenoid)

Pump numbers|2015, 2017, 1551, 1531, 2016, 2142, 1636

1. Short the two large solenoid terminals with a screwdriver or pliers. 2. If the motor does not run: check voltage at the solenoid battery terminal. It should not fall below 11.0 VDC while shorted. Then check the ground, then suspect the motor. 3. If the motor runs: check for at least 10.5 VDC on the small exciter terminal (usually blue) during a command. Check that the other small terminal is grounded to the pump ground stud. Otherwise replace the solenoid.

Quick test: jumper 12V from the solenoid battery terminal to the small blue terminal. If it clicks and the motor runs, the motor and solenoid are good. Go to the control circuit.

Solenoid part|1444 (SPX with Smart Start: 7055)

The same test works on SPX and Fenner units, except Fenner Smart Start solenoids. Wire colors may differ. Motors vary, so match the pump number to the motor chart or send Equalizer a photo.

Bi-directional pumps, two solenoids

Pump numbers|2390, 2532, 2542 (motor 2605, two solenoids 1444)

These are 3.7 in wound-field motors with two power studs, one for extend and one for retract. The motor grounds through the case. The extend solenoid has the BLUE small-terminal wire. The retract solenoid has the GREEN wire (black on some single-function trailer jack units). No run extend: short the large terminals of the blue-wire solenoid. No run retract: short the large terminals of the green-wire solenoid. Then follow the same power, ground and exciter steps as the uni-directional pumps.

The motor can be good in one direction and bad in the other. Always test both.

Bi-directional pumps, relays or contactor (reversing PM motor)

2727, 2754 with relays|Motor 2751, two 70 A relays 2735 (trailer jacks only)

2727, 2754, 3040, 3041, 3043 with contactor|Motor 2751, contactor 2994

Do not jump or short the relays or contactor on these units. It can cause a dead short to ground that damages the relays and wiring. Use a voltmeter. Apply power directly to the motor only with the relay or contactor leads disconnected.

No run either direction: measure across the two motor end terminals while pressing extend and retract. It should read at least 10.5 VDC. Good voltage means a bad motor. Low voltage means a weak battery or bad connections. No voltage means check the battery, the supply wiring, the relays or contactor, and the switch and harness. On contactor units, check for 12.5 VDC across the contactor + and - terminals. Also check the black center spade (exciter ground).

Runs one direction only: check exciter voltage on each relay or contactor. GREEN is retract. Extend is BLUE on contactor units, and probably white with black trace on relay units. If you have 10.5 VDC or more and no click, the relay or contactor is bad. If there is no voltage, look at the plug, switch or harness.

Relay unit supply|Red and black at least 10 gauge, from vehicle battery. Fuse or breaker at least 60 A. Up to 60 A at 10.5 VDC. Go larger if the run is over 6 ft.

Common failures

Voltage drops under load: corroded cable ends or a weak battery.

Missing or loose port plate ground stud cable.

Solenoid clicks but motor does not run: bad solenoid contacts or bad motor.

No exciter voltage: fault upstream in the switch, control panel or harness. On auto-level systems, use the Auto-Level troubleshooting guide.

These motors can draw up to 160 A. Keep tools and rings clear of the large terminals when shorting them.

EQUALIZER|Basic Trouble Shooting Motor & Solenoid for Equalizer Hydraulic Pumps (Equalizer Systems, via myrvworks.com)