89 mustang Door Lock/Unlock

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=1637
Printed Date: July 21, 2025 at 7:00 PM

Topic: 89 mustang Door Lock/Unlock

Posted By: xlant
Subject: 89 mustang Door Lock/Unlock
Date Posted: July 01, 2002 at 7:35 AM

I'm trying to install an alarm, it is a Prestige Model APS-25KB, also name APS-250 at Audiovox.com. My only problem is the Door Lock/Unlock, The car is not keyless entry and I found those pink/green and pink / YELLOW wires, they are thick so I presume the car shouldn't have built-in relays. When the lock switch is depressed, I get +12VDC on the meter at these wires (Lock and Unlock)

The alarm instruction tells me that I have to connect two wires from the alarm control box to the above described wires (Door Lock Outputs), so I did, but nothing happens when I press the keyless' button of the alarm system. Do I need a relay and should the pulse coming out from the alarm control box be 12 VDC?

Replies:

Posted By: mobiletoys2002
Date Posted: July 01, 2002 at 8:37 AM

OK you will need two relays to interface whith these door locks. YOU have a reversaL REST A T GROUND DOOR LOCK SYSTEM IN YOUR CAR there are no factory relays your door lock motors get 12 volts positive from the switch and they also get negative ground from the switch.the two wires you found should rest at ground and when you lock the door they should pulse positive, and the other wire should do the same when you unlock the doors. To wire these relays you will have to cut your lock wire in half, and on one of your relays the switch side of that wire will go to pin 87a now the motor side of that wire will go pin 30. pin 86 will be from your alarm you will want to send this a negative pulse.pin 85,87 both get 12 volts positive.now do the same thing on the other relay with the unlock wire

pin 85/87 both get positive twelve volts

pin 86 will be the negative output from the alarm

pin 87a will go to the switch side of your wire you cut

pin 30 will go to the motor side from thesame wire

now do the same thing to wire the other relay using the second wire from theswitch remember the corect wires will pulse 12 volts when locked or unlocked and rest at ground posted_image

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Posted By: mobiletoys2002
Date Posted: July 01, 2002 at 8:49 AM

you have to be verry carefull with this type of door lock system .make sure you test these wires first.. the colors you said i think are correct but make sure before wiring this.. there should be five wires on your door lock switch one of these wires will show constant all the time the other 2 will show ground all the time regardless if you move the switch.. and then there will be two more one will show positive on lock the other will show positive on unlock.your alarm shouold be set to send a negative pulse to trigger these relays.good luck

Posted By: xlant
Date Posted: July 01, 2002 at 9:46 AM

Thanks ,

I think I got this. could I know what type of relays (how many pins on the relays) are required, there are so many in the market.

I guess I should disconnect the two wires from the alarm module to the door lock as they don't do anything at this time.

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P.Doucet

Posted By: mobiletoys2002
Date Posted: July 01, 2002 at 9:51 AM

YOU WANT A STANDARD SPDT (SINGLE POLE DOUBLE THROW RELAY),YOU CAN FIND THESE AT A RADIO SHACK OR ELECTRONICS STORE. THERE ARE 5 PINS ON THE RELAY YES YOU CAN DISCONECT THAT FOR NOW AS IT IS DOING NOTHING. GOOD LUCK