How To Keep Cooling (and Other) Systems Running After Power Is Off

Cooling Systems Components

Would you like to have certain systems, like your cooling system or turbocharger oiling system, to continue running after power to the vehicle is turned off?

The solution is found is in a time-delay relay. Jeremy Stoermer from Holley shows you below how to make it happen, but take note of the solid-state relay block that essentially replaces 4 relays and all the related wiring. More on these relay blocks below, but these solid-state units can easily control electric fans, water pumps, nitrous solenoids, auxiliary lighting, and any other electrical accessories that would normally require a relay.

The Time-Delay Relay

The time delay relay used is capable of adjustable time delay allowing you to control any device. It utilizes the popular Bosch-style connections and is frequently used in automotive sound and security installations. It easily switches 30 amps of current and peaks of 30 amps with minimal draw on the coil.

  • Standard automotive style relay
  • Adjustable time delay off with 2 seconds to 3 minutes timer with internal potentiometer
  • 20 amp / 30 amp rated contacts
  • SPDT – Single pole Dual throw
  • Low 1volt (1k Ohm) trigger voltage
  • More info and pin configuration below.

► Get it on eBay: 30 Amp Programmable Time Delay Relay

How To Incorporate Time-Delay Relays into MSD’s Solid State Relay Blocks

Follow along as Jeremy shows you how the MSD’s Solid State Relay was used with a time-delay relay to keep engine cooling fans running for a period of time after the engine is shut down.

In case you need it:

How To Wire An Automotive Relay

A 4 or 5 pole relay is a simple and effective solution to switching power to high current devices and loads. Here’s how to wire one up.

Frostbite Fan/Shroud Electric Relay Kit

This relay kit will allow you to custom configure your fans as pusher or puller resulting in increased cooling performance and a reduction in noise/vibration in your engine bay.

► Get it from Holley: https://www.holley.com/…/FB403

30 Amp Programmable Time Delay Relay

The time delay relay used is capable of adjustable time delay allowing you to control any device. It utilizes the popular Bosch-style connections and is frequently used in automotive sound and security installations. It easily switches 30 amps of current and peaks of 30 amps with minimal draw on the coil.

Features and Specifications

  • Standard automotive style relay
  • No mounting tab
  • Delay Off Version
  • Momentary pulse to trigger latching (Requires the removal of 12 volts on the trigger to initiate timer, with constant 12 volts relay is latched like an ordinary 5-pin relay, no timer)
  • Low 1volt (1k Ohm) trigger voltage
  • Adjustable time latching from 2 seconds to 3 minutes with an internal potentiometer, the time delay extends or delays the termination of the relay
  • Built-in diode to stop timer feedback issues
  • Internal green LED to indicate status
  • Non-removable cap
  • 20 amp / 30 amp rated contacts
  • SPDT – Single pole Dual throw
  • 12 Vdc rated coil with minimum 8 volts to trigger
  • Power consumption @ 12Vdc 120 mA
  • Idle current draw .002 mA
  • Conventional 87, 87a, 30, 86, and 85 pin locations
  • SPDT Change Over NC/NO (form C)
  • Compatible with most insulated and non-insulated terminals and relay sockets
  • Dimensions 1-1/4″ (W) x 1-1/4″ (D) x 2″ (H) with terminals

Pin configuration

  • Pin 30 – Must have constant or accessory 12 volts all-time, as this is what powers the circuit on the relay
  • Pin 85 – Ground
  • Pin 86 – Single-pulse (+12 volts) to trigger time delay off (Constant 12 volts can be applied and once +12 volts is removed relay will stay latched for duration of timer.)
  • Pin 87a – +12 volt output (Normally closed contact – on except when time delay is active)
  • Pin 87 – +12 volt output (Normally open contact – on for duration of set time)

► Get it on eBay: 30 Amp Programmable Time Delay Relay

MSD Solid-State and High Current Solid-State Relay Blocks

Clean up and simplify your wiring with MSD’s Solid State Relay Modules. The units are a simple and easy way to wire multiple circuits in your car without the hassle of bulky analog relays and fuses.

MSD Stand Alone Solid State Relay Block

This module takes the place of 4 standard relays and eliminates unsightly wiring. Four independent channels can be activated using either power or ground. Each channel is capable of handling 50 Amps for up to 8 seconds or 20 Amps of continuous current. With 4 channels providing up to 200 Amps of momentary or 80 Amps constant combined power, you can easily control electric fans, water pumps, nitrous solenoids, auxiliary lighting, and any other electrical accessories that would normally require a relay.

LED status indicators ensure proper wiring and operation of each channel. Should a problem arise, the relay block has built-in automatic over-temp, short circuit, and overload protection. The 7564 can easily be mounted using the supplied hardware and mounting tabs that can be rotated 90° to accommodate various mounting locations. Its compact and clean design will make your wiring project a breeze.

► Get it from Holley: https://www.holley.com/…/7564

Features:

  • 4 Channels, Up to 20 Amps continuous each and 50 Amps for 8 seconds
  • Clean, easy install with minimum wiring
  • Over temp, short circuit and overload protection
  • Diagnostic LED’s
  • Multiple mounting options
  • Activate with power or ground
  • Channels can be run in parallel for devices requiring more than the single-channel rating
*AmperageMax On Time
20Continuous
253 + Hours
303 + Hours
3512 Minutes
4035 Seconds
4512 Seconds
508 Seconds

MSD’s solid-state relays have been an extremely popular solution to clean up automotive wiring and create a simple, reliable, electrical solution. However, the new line of high-current relays expands upon the original’s capability with four 35 amp channels for even more functionality. The units are easy to install, each output can be triggered by switched power or ground, and they offer a combined output of 140 amps.

MSD High-Current Solid State Relay Block

This high current module takes the place of 4 standard relays and eliminates unsightly wiring. Four independent channels can be activated using either power or ground. Each channel is capable of handling up to 35 Amps of continuous current, providing up to 140 Amps of power. It also has the capability of Pulse Width Modulation (PWM). With a PWM input, you can control the output at a rate of 15 hertz and a duty cycle of 50-90%. Controls electric fans, water pumps, nitrous solenoids, auxiliary lighting, and any other electrical accessories that would normally require a relay.

LED status indicators ensure proper wiring and operation of each channel. Should a problem arise, the relay block has built-in automatic over-temp, short circuit, and overload protection, as well as a channel reset. The solid-state high current relay can easily be mounted using the supplied hardware and mounting tabs that can be rotated 90° to accommodate various mounting locations. Its compact and clean design will make your wiring project a breeze.

► Get it from Holley: https://www.holley.com/…/75643-HC

Features:

  • Operates from 7-Volts to 20-Volt supply
  • 4 Independent Channels, 35 Amps each continuous or 100 Amps for 8 seconds
  • Combined total continuous current rating of 140 amps
  • Channels can be run in parallel for devices requiring more than 35 Amp single-channel rating
  • Clean, easy install with minimum wiring
  • Over-temp, short circuit and overload protection
  • Diagnostic LED’s and status indicators
  • Multiple mounting options
  • Single wire activation by switching power or ground
  • Available in Red or Black
  • A PWM signal can be used in the Solid-State Relay Module with a maximum frequency of 150 hertz and a duty cycle range from 50% to 90%.
*AmperageMax On Time
35Continuous
403 + Hours
4530 + Minutes
5012 Minutes
6035 Seconds
8012 Seconds
1008 Seconds