09 corolla rear defogger/ trunk pop

I have a 09 Corolla. Do I need to use a relay for the rear defogger? The diagram says ( - latched @ 10 pin plug pin 2 switch or white 40 pin plug pin 38) Also would I need a relay for the trunk release to work as well? diagram says( trunk hatch pin (green)dash white pin plug) or ( trunk hatch release @ kick panel ) or (release motor 5 pin @ kick panel) ?? Any help would be appreciated!

rear defrost TAN (-) @ defroster switch in dash. no relay needed trunk release PINK (REV) @ driver kick harness to back. relay needed Alternative: trunk release GREY (-) Pin 20 @ Driver kick. white 22pin plug no relay required.Ted

2nd Year Tier 1 Medical School

Still installing as a hobby...pays for groceries

Compustar Expert

Ok I got the defroster working. However with the rear trunk I tried the "No relay required" technique @ pin 20, 22pin plug and got nothing! That wire doesn't seem to be (+) or (-) at either time. Maybe the relay method with 5 wire? IF so how would I go about connecting?

are you popping the trunk with the oem remote? worst case use the reverse polarity trunk wire in the kickpanel and wire up a relay. 85 - negative trunk release from unit 86 - constant 12v fused 5 amp should be sufficient cut trunk wire in half 87- constant 12v fused with 86 87a- car side of trunk wire towards front of the car 30 - load side of trunk wire towards back of the carTed

2nd Year Tier 1 Medical School

Still installing as a hobby...pays for groceries

Compustar Expert

Yes im using OEM remote to activate trunk pop. I will use the relay system. I'll let u know how it goes! THANKS!

U got a diagram for this?

above post has the wiring instructions.Ted

2nd Year Tier 1 Medical School

Still installing as a hobby...pays for groceries

Compustar Expert

Ok so 86 & 87 can be tied together with a 5 amp fuse going to +12 constant? Cut trunk wire in half, now one end of trunk wire should be connected to the +12 as well? 87a & 30? Im sorry im too confused with this. Step by step if possible please?

Also which relay type should I use? SPDT or SPST?

The relay must be a SPDT. 

Circuit explanation :

The relays' pins 30 to 87a are normally closed ( internally connected inside the relay ) and make a normal complete circuit

for the Trunk Motor solenoid circuit.  The car and it's Trunk Release will operate normally.

When the after-market system executes a Trunk Release, it outputs a one second (-) pulse on it's Trunk Release wire.  This

wire is connected to the (-) side of the relays' coil, Pin 85.  The (+) side of the relays' coil, Pin 86, is connected to +12V constant.

This pulse makes the relay's coil energize for one second.  When the relay energizes, it moves an internal armature, breaking

the connection between Pins 30 and 87a and making a 1 second connection between Pins 30 and 87.   

At this point, the vehicles' trunk release system is disconnected ( Pin 87a is open and no longer connects to the trunk release

solenoid ) and the +12V signal from Pin 87 is sent out Pin 30 to the cars' trunk release solenoid.  The trunk pops.

At the end of one second, the after-market systems Trunk Release output ends, the relay de-energizes, the internal armature

returns to it's normal, at rest, position and Pins 30 to 87a are re-connected.  Everything is back to normal.

The reason the cars circuit must be opened ( rather than just applying +12V to this wire ) is because the car's circuit rests

at chassis ground.  Applying +12V without first breaking the wires' connection to the cars' control circuit will just blow the fuse in the after-markets (+) Trunk Release circuit.

Here is a nice relay operation explanation :  http://www.bcae1.com/relays.htm   The circuit you are adding with the relay

is called a 5 wire Alternating 12 V Positive circuit.  Here is a link :  https://www.the12volt.com/relays/relaydiagram3.htmlThe above diagram is for door locks so your circuit is basically just the unlock side, using the (-) Trunk Release as controland the cars trunk release motor solenoid wire instead of the Unlock wire shown.

Soldering is fun!