Hayward ProLogic Auxiliary Equipment Not Running
Quick Summary
- The ProLogic uses high-voltage electromechanical relays rated 120/240VAC, 300W, 25A. Do not exceed these specs — overpowered equipment will damage relays.
- Top relay bank: Filter, Lights, AUX 1, AUX 2. Bottom relay bank: AUX 3–6. If the relay is in the wrong socket (especially on P-4 or PS-4 models), the wiring harness may not reach the correct relay.
- The ProLogic will ONLY attempt to engage a relay if the corresponding LED is illuminated on the local display.
- Service mode bypasses all interlocks and automation — use it to test relay hardware independently of scheduling and safety logic.
- Relay replacement part: GLX-RELAY.
How ProLogic Auxiliary Relays Work
The ProLogic controls external equipment through high-voltage electromechanical relays mounted on the main PCB. Terminal F contains two relay banks: the top bank holds relays for Filter, Lights, AUX 1, and AUX 2 (relays 1–4). The bottom bank holds relays for AUX 3–6. Each relay is driven by a low-voltage coil signal from the main board — when the board closes the coil, the relay switches the high-voltage load side on or off.
When a relay LED on the display is illuminated but the equipment does not run, the fault could be anywhere: the relay coil is not receiving drive voltage from the board, the relay contacts are not closing, the relay is in the wrong socket, there is no source power at the relay input, or the problem is in the equipment or its wiring rather than the relay itself.
Step-by-Step Troubleshooting
Owner-Level Checks
Step 7A: Check the AUX relay LED
- Press the Auxiliary button on the local display that corresponds to the equipment in question.
- The display should show "[AUX Name] Turned On" and the corresponding LED should illuminate.
- If the LED fails to illuminate when you press the button: the display is not sending the command, or an interlock is blocking it. Proceed to the service mode test (Step 7B).
- If the LED illuminates: the ProLogic is commanding the relay on. Proceed to relay testing (Step 7D).
Check for interlocks
- Some AUX relays have interlocks configured — for example, the spa blower may be interlocked to only run when the spa is active. If the LED will not illuminate outside of service mode, an interlock may be preventing it.
- In service mode, interlocks are suspended. If the LED illuminates in service mode, exit service mode and press the AUX button — the display should explain why it is locked out.
Tech-Level Checks
High Voltage Warning
The relay load side carries 120VAC or 240VAC depending on how the equipment is wired. Use appropriate PPE and ensure you have a clear understanding of the circuit before probing. For 240VAC equipment, both load terminals (terminals 2 and 4) should be tested to ground.
Step 7B: Service mode test
- Press the Service Mode button on the local display. Service mode suspends all schedules, interlocks, and automation.
- Press the AUX button for the relay in question.
- If the LED illuminates in service mode: a control-level feature (interlock, schedule conflict, or safety logic) was blocking the relay outside of service mode. Contact Hayward tech support at (908) 355-7995 to identify and resolve the specific interlock.
- If the LED does NOT illuminate in service mode: the local display is not generating the relay drive command — replace the local display (matching the model number on the inside of the control door).
Step 7C: Verify whether the equipment runs in service mode
- With the AUX LED illuminated in service mode, does the equipment wired to that relay actually turn on?
- If yes — exit service mode and manually press the AUX button to turn it on. The display will explain any interlocks preventing operation. Contact Hayward support at (908) 355-7995 for interlock resolution assistance.
- If no — proceed to Step 7D to test the relay coil (low voltage side).
Step 7D: Test the relay low-voltage side (coil circuit)
- With the AUX LED illuminated, carefully remove the relay bracket to expose the low-voltage side of the relay.
- Using a multimeter set to DC voltage, test between the red and black wires on the suspect relay coil.
- You should see 20–25VDC when the LED is on (the main board is driving the coil).
- If no or low voltage: the main board is not driving this relay's coil — proceed to Step 7E to check the relay socket/wiring harness.
- If correct (20–25VDC): the relay coil is being driven. Proceed to Step 7F to test the high-voltage side.
Step 7E: Inspect relay socket and wiring harness
- The ProLogic board has two relay sockets: top and bottom. On P-4, PS-4, and PS-8V models, only the top socket should be populated — the bottom socket should remain open.
- Verify the wiring harness for the AUX relay in question is plugged into the correct socket. If it is in the wrong socket: power down, move the harness to the correct socket, and retest.
- If the harness is in the correct socket and the relay is still not receiving coil voltage (20–25VDC), replace the main board (GLX-PCB-PRO) — the relay driver circuit on the board has failed.
Step 7F: Test relay source power (line side — terminal 1)
- With power on and the AUX LED illuminated, use a multimeter set to AC voltage to test terminal 1 of the suspect relay against ground.
- For 120VAC equipment: terminal 1 should show 120VAC. If not, the breaker feeding this relay circuit has no power — correct at the panel.
- For 240VAC equipment: also test terminal 3 against ground — both should show 120VAC (legs of 240V supply).
- If source power is present, proceed to Step 7G.
Step 7G: Test relay load side (terminal 2)
- With the AUX LED illuminated and source power confirmed, test terminal 2 against ground for 120VAC. For 240VAC equipment, also test terminal 4 against ground.
- If no voltage is present on terminal 2 (or terminals 2 and 4 for 240VAC): the relay contacts are not closing — replace the relay (GLX-RELAY).
- If voltage is present on the load side terminals but the equipment still does not run: the problem is in the equipment wiring or the equipment itself, not the relay.
Frequently Asked Questions
The AUX 1 LED comes on but nothing happens. Where do I start?
With the LED on, test the low-voltage coil side of the relay first (terminal red/black wires) for 20–25VDC. If coil voltage is correct, move to the high-voltage side — test terminal 1 for source power, then terminal 2 for load power with the relay energized. If load power is present but equipment doesn't run, the issue is in the equipment or its field wiring.
The pool light relay LED comes on but the light won't come on. Could it be a bad relay?
Yes, but check source and load power first. Low-voltage pool lights (12VAC) are powered from a transformer, not directly from the relay — confirm the light transformer is receiving 120VAC on its primary and outputting 12VAC on its secondary. If the transformer is fine and the relay load side shows 120VAC, check the light fixture itself and the low-voltage cable from the transformer.
Can I replace just one relay on the ProLogic board?
Yes. The relays on the ProLogic board are individually replaceable — part number GLX-RELAY. Confirm which relay position is faulty before ordering. You do not need to replace the entire main board for a single failed relay unless the relay socket or driver circuit on the board is damaged.
What does "interlock" mean in the ProLogic context?
An interlock is a programmed logical dependency — for example, the spa blower cannot run unless the spa is in spa mode, or the cleaner cannot run unless the filter pump is on. Interlocks are configured in the ProLogic's automation setup and are suspended by service mode. If an interlock is blocking an AUX relay, the display will explain it when you try to manually press the button outside of service mode.