Automotive Relay Product Guide

Automotive relays come in many shapes and forms. The most basic consisting of an electromagnetic switch.
The term "relay" is sometimes also used to describe small electronic controllers such as glow plug controllers etc. which also contain electronic circuits

*Function*	*Typical terminal designation*	*Operation*
Normally Open 4 pin relay 12v 20A 4 pin relay 12v 30A relay with detachable bracket 12v 30A relay with inc blade fuse 12v 40A relay NO 4 pin 12v 70A heavy duty 4 pin relay 24v 20A 4 pin NO relay	30 Supply Input 87 Supply Output 85 Coil ground or -ve 86 Coil trigger	A control circuit between pins 85 & 86 eg, with light duty control switch and wiring , may be used to switch a second circuit with heavier current load via wiring between pins 30 and 87
Heavy Duty Automotive Relay 12v 200A relay 24v 100A relay	30 Supply Input 87 Supply Output 85 Coil ground or -ve 86 Coil trigger	Normally open relay often used on construction plant for starter circuit control
Double Make & Break	30 Supply Input 87 Supply Output(1) *87b* Supply Output(2) 85 Coil ground or -ve 86 Coil trigger	Similar operation to the standard 4 pin Normally Open relay but has a second terminal in parallel to the output terminal.
Changeover Relay 5 pin 12v 20A/30A relay 12v 30A/40A relay 24v 10A/20A automotive relay	30 Supply Input 87 Supply Output when relay off. *87a* Supply Output when relay on. 85 Coil ground or negative. 86 Coil trigger or positive from switch.	A control circuit wired to pins 85 & 86 eg, with light duty control switch and wiring , may be used to relay switching of a second circuit with heavier current wired to pins 30 and 87 when control circuit is OFF , changing to pins 30 and 87a when control circuit is ON
Flasher Relay SAFU003 direction indicator relay SAFU005 flasher relay 4 pin with C terminal for trailer lights warning lamp	31 Ground or Negative 49 Supply Input battery +ve 49a Supply output to column switch then to indicator lamps. *49b* Second output to direction indicator lamps *49c* Third output to direction indicator lamps	The flasher relay or direction indicator relay pulses power to indicator lamps causing to flash on and off at between 60 and 120 flashes per minute in normal operation. *Always check pin position configuration of relay is correct before fitting*
Fuel Pump Relay	1 Ignition Coil (negative pulse) 15 Ignition supply from ignition switch 31 Ground or negative 50 Starter motor cranking signal 85 ground for coil may be switched via engine computer. 30 Battery +ve Supply 87 +ve Supply output to fuel pump. *Wiring terminal designation may be vehicle specific, consult manufacturers specification.*	The fuel pump relay may supply power to the fuel pump for a couple of seconds to prime fuel system then shuts off until control circuit via engine control computer grounds coil of relay to switch on again if engine rotation signal is present from crankshaft position sensor or distributor pickup. Fuel pump relays are vehicle specific in application.
Glow plug controller relay	*(L)* dashboard preheat warning lamp *(85) or (31)* coil negative *(86) or (15)* from ignition switch , coil trigger +ve. *(30)* Battery B+ +ve supply (87) +ve output to energise pre heat plugs (glow plugs) *Wiring terminal designation may be vehicle specific, consult manufacturers specification.*	The glow plug controller is typically a timer relay which allows diesel glow plugs to heat up for approx 10 seconds to provide pre heating of air in the engine pre combustion chambers to allow easier cold starting. May also have post heat functions. Operation may also be controlled by engine control unit on later vehicles.
Time delay relay	*Wiring terminal designation may be vehicle specific, consult manufacturers specification.*	Time delay relays may be used for such applications as wash wipe interval, heated rear window, time delayed motor operation, bus door operation.