Hayward TriStar VS 950 Will Not Start Or Power Up: Step-By-Step Checks

What "Pump Will Not Start" Actually Means On This Model

On the TriStar VS 950, "will not start" can mean:

• Display completely dark and unresponsive.
• Display lit, but pressing Speed 1–4 or running a timer does nothing.
• Check System messages like "Pump failed to start" after the drive tries several times.

The drive expects a solid 230 V supply within a tight range. If it does not see that, or if the motor cannot spin freely, it will not start the pump and will often log an event.

Step-By-Step Troubleshooting

Step 1: Confirm the basics at the breaker

Owner-level:

1. Find the breaker feeding the pump and flip it fully off, then back on.
2. Verify no other heavy loads are tied into that same breaker if possible.

Tech-level:

• Confirm breaker size is appropriate for the pump nameplate current.
• Look for obvious signs of heat at the breaker or panel lugs.

If the breaker will not reset, you likely have a short or an internal drive fault that needs a pro.

Step 2: Verify line voltage at the pump

Tech-level:

1. With power on and proper PPE, remove the drive wiring cover.
2. Measure voltage between the two hot legs at the pump terminal block.
3. You should see roughly 230 V. Under 207 V or above 253 V is out of spec and will cause trouble.

If there is no voltage at the pump:

• Work back toward the panel: junction boxes, timer enclosures, or splices.
• Correct any miswired or open connections before touching the pump further.

If line voltage is outside the acceptable range under load, involve an electrician.

Step 3: Check terminal tightness and wiring layout

With power off:

1. Inspect each conductor at the pump terminals. Loose screws, stranded wire with stray strands, or half-inserted wires are common.
2. Confirm the ground connection is landed on the proper lug.
3. Make sure line conductors are routed through the "POWER" opening, and any control/comm wires use the "DATA" opening.

Owners can visually inspect; techs should re-land and torque connections as needed.

Step 4: See what the display is telling you

If the display is lit:

1. Check for any Check System messages.
2. Press a preset speed button and confirm the LED for that button lights.
3. Look at the main run screen for a commanded speed and watt draw.

If you command a speed and:

• Speed shows, watts stay at zero, and the motor is silent: the drive might not be sending power to the motor.
• A message like "Pump failed to start" appears: the drive tried several times and gave up.

Make note of any messages; they guide you toward electrical vs mechanical issues.

Step 5: Inspect and spin the shaft

With power off and locked out:

1. Remove the motor fan shroud at the back of the motor.
2. Use a hex key in the motor shaft socket to gently turn the shaft.

What you are looking for:

• Smooth, easy rotation: wet end is probably free.
• Stiff, gritty, or seized shaft: likely impeller jam, melted seal, or failed bearings.
• Free then suddenly tight: misaligned parts or debris inside.

If the shaft is locked, you need to open the wet end and move into the drive overload / stalled pump diagnostic workflow.

Step 6: Check the event log and diagnostics

Tech-level, with power restored:

1. Use the MENU button to enter the Diagnostics menu.
2. Scroll to line voltage, motor current, and power usage.
3. Review the event log to see whether any pump failed to start or overload events are stored and how long ago.

If the pump never even attempts to start, and there are no recent events, suspect control wiring or remote mode (covered in the timers/remote article).

Step 7: Rule out remote control mode conflicts

If this pump is tied into automation:

1. Enter the Configuration menu and find Remote Control Mode.
2. If it is set to Relay Control or Hayward control, local preset speeds are limited or disabled.
3. Confirm the external control actually calls for the pump.

If you want to test locally, temporarily set the mode to Standalone/Hayward and use a preset speed to command the pump.

Common Parts That Fix This Problem

Depending on what you find:

• Drive assembly if the unit has power and logic but never energizes the motor and other causes are ruled out.
• Motor and seal kit if the shaft is stiff or seized from a seal leak or bearing failure.
• Terminal block and wiring repairs when overheated or damaged connections are found.

Avoid guessing. If voltage, wiring, and mechanics all check out but the drive will not start the motor, replacement of the drive or entire motor/drive assembly is often the cleanest solution.

Model-Specific Notes

• The TriStar VS 950 expects 230 V only; feeding it with 115 V will not work.
• Preset speeds and Quick Clean are disabled when the pump is under relay control or talking to compatible automation, so local buttons may not start the pump in those modes.
• Internal protection will prevent repeated hard starts if the motor stalls; this is why you may only hear a brief "bump" or see a message after several attempts.

How To Prevent "Dead Pump" Callbacks

• Land wires cleanly and fully inside the terminals during installation.
• Use proper conductor size for the run length to keep voltage drop under control.
• Keep the drive and wiring compartment dry and protected from direct spray.
• Educate owners to call before they start flipping breakers repeatedly.