09 corolla rear defogger/ trunk pop

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=137868
Printed Date: May 12, 2025 at 12:07 PM

Topic: 09 corolla rear defogger/ trunk pop

Posted By: thespinman82
Subject: 09 corolla rear defogger/ trunk pop
Date Posted: December 04, 2014 at 2:43 PM

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!

Replies:

Posted By: tedmond
Date Posted: December 04, 2014 at 5:11 PM

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.

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Ted
2nd Year Tier 1 Medical School
Still installing as a hobby...pays for groceries
Compustar Expert

Posted By: thespinman82
Date Posted: December 05, 2014 at 2:18 PM

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?

Posted By: tedmond
Date Posted: December 05, 2014 at 3:11 PM

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 car

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Ted
2nd Year Tier 1 Medical School
Still installing as a hobby...pays for groceries
Compustar Expert

Posted By: thespinman82
Date Posted: December 05, 2014 at 4:00 PM

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

Posted By: thespinman82
Date Posted: December 05, 2014 at 4:04 PM

U got a diagram for this?

Posted By: tedmond
Date Posted: December 05, 2014 at 7:59 PM

above post has the wiring instructions.

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Ted
2nd Year Tier 1 Medical School
Still installing as a hobby...pays for groceries
Compustar Expert

Posted By: thespinman82
Date Posted: December 06, 2014 at 12:18 AM

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?

Posted By: thespinman82
Date Posted: December 06, 2014 at 12:20 AM

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

Posted By: kreg357
Date Posted: December 06, 2014 at 5:56 AM

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 : https://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.html
The above diagram is for door locks so your circuit is basically just the unlock side, using the (-) Trunk Release as control
and the cars trunk release motor solenoid wire instead of the Unlock wire shown.

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Soldering is fun!

Posted By: thespinman82
Date Posted: December 06, 2014 at 11:12 AM

Posted By: thespinman82
Date Posted: December 06, 2014 at 11:13 AM

Would that pic be correct??

Posted By: kreg357
Date Posted: December 06, 2014 at 11:27 AM

Yes, but the cut vehicle trunk solenoid wires must be connected to specific relay terminals. The vehicle trunk solenoid wire side that goes to the trunk solenoid is connected to Pin 30. The side of the wire that comes from the front of the car goes to Pin 87a.

posted_image

same as this :

posted_image

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Soldering is fun!

Posted By: thespinman82
Date Posted: December 06, 2014 at 1:15 PM

Thanks for clearing this up for kreg 357!

Posted By: tedmond
Date Posted: December 06, 2014 at 6:24 PM

good guy, Kreg posted_image

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Ted
2nd Year Tier 1 Medical School
Still installing as a hobby...pays for groceries
Compustar Expert