528t for fans and electric water pump

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=96923
Printed Date: June 14, 2025 at 4:27 PM

Topic: 528t for fans and electric water pump

Posted By: S10Fan
Subject: 528t for fans and electric water pump
Date Posted: September 06, 2007 at 9:29 AM

I need a little help with a 528T.

I’ve used 528’s in the past and had zero problems getting them wired and functioning. This is probably a simple deal I’m just not getting it. I need the 528 to activate another relay(s) when ignition power is cut off. The additional relays will keep an electric water pump and 2 radiator fans running for the max 90 seconds. I’m also planning on installing a diode between the ignition source and the fan/pump relays.

Any wiring help would be much appreciated, Thanks!

Replies:

Posted By: hotwaterwizard
Date Posted: September 08, 2007 at 3:55 PM

It is a Pulse timer You have to give it a pulse. You could have a relay latch when the ignition is on then pulse it when the power is turned off with the momentary to pulse circuit from this site. The use the 528 drop the power after 90 seconds.

Here is what I came up with.

posted_image

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: S10Fan
Date Posted: September 09, 2007 at 8:16 AM

Out of frustration I plundered forward. Also have a couple spare 528’s. LOL.
Anyway, here’s what I wired up,

Red-12V+ fused
Black-12V-
Yellow-12V+ fused
Black Stripe- Ignition fused
Brown- To Fan/Water Pump Relay (with diode)
Blue Loop- cut
Orange- not used

When I turn off the ignition the fans and water pump stay on for the desired amount of time. The fans and water pump also work as desired with the ignition on. So far so good.

I printed out your diagram for future reference. Thanks!

Posted By: hotwaterwizard
Date Posted: September 09, 2007 at 1:16 PM

I don't have the benifit of having one of these to experiment with.

In fact I have never even seen one. I understand how they work though.

The first part of the pulse is provided when the power is applied and the second is provided when the power is turned off. Cool. I didn't think about that solution, Well done! posted_image

Is this what you did?

posted_image

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: S10Fan
Date Posted: September 09, 2007 at 2:41 PM

Exactly!

I must admit though, the 1st half and 2nd half of the pulse thing was pure luck. Actually, until you posted your response I never thought of it in that manner.

Thanks!

Posted By: 69elco
Date Posted: October 27, 2007 at 2:36 PM

Hi,

I just tried this... The timer times out after ignition on and ignition off. What am I missing?