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Printed From: the12volt.com
Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=1577
Printed Date: May 11, 2025 at 5:52 PM
Topic: Scanner
Posted By: iimm_Matt
Subject: Scanner
Date Posted: June 28, 2002 at 11:15 PM
Ok, I've spent my entire friday night trying to wire in this freaking scanner!! Please help! The scanner has three wires: +12 volt, ground, and ground when on (you ground this wire to turn on scanner). I've got the +12 volt and ground wires hooked up, but here is my problem: My alarm doesn't have a "ground when armed" output. Secondly, the starter kill wires (as best I can tell) are ground when DISARMED!!! So the only output I have is the exact opposite of what I need!!!! I've tried wiring it through a relay, with the starter kill wire on 85, +12 constant on 86, ground on 30, and the activation wire on 87a. THIS DOESN't WORK!!! why?????? How can I do this?
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Matt
Replies:
Posted By: Velocity Motors
Date Posted: June 28, 2002 at 11:54 PM
Are you sure that the alarms starter disable wire is a + output ?? Most of the systems that I've worked on has a ( - ) starter disable output. If the unit that you have is indeed a ( + ) output you will need to convert the signal coming from that wire to a ( - ) by wiring a relay . I would test the wire that you think is ( + ) with a DMM and if it's not a ( + ) then hook up this wire straight to the GROUND WHEN ON wire of the scanner. ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: mobiletoys2002
Date Posted: June 29, 2002 at 12:25 AM
when you say this does not work do you mean that the scanner turns on when you turn your car off but not when you arm the alarm.you will need a diode on that ground when armed output from the alarm.if the diode is not there the scanner will come on everytime you turn the car off defeating the purpose of it coming on with the alarm.
Posted By: GlassWolf
Date Posted: June 29, 2002 at 12:26 AM
neg. trigger is usually the door-pin trigger, or external sensor trigger from what I've seen.
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-GlassWolf
Pioneer Stage-4, Orion, DynAudio, Fi
Posted By: mobiletoys2002
Date Posted: June 29, 2002 at 12:29 AM
well your relay wiring you posted is wrong that is why that did not work if your alarm was putting out a positive when armed then yes that would go to pin 86 but ground would go to pin85, pin 87 would go to ground and pin30 will go to the yellow wire on the scanner
Posted By: iimm_Matt
Date Posted: June 29, 2002 at 7:15 AM
No, I'm not sure that the wire is putting out positive when armed, but I am SURE that it is putting out a ground ONLY when DISarmed. I don't have a DMM.... help! ------------- ------------
Matt
Posted By: iimm_Matt
Date Posted: June 29, 2002 at 7:17 AM
My relay was supposed to not rely on +12 volt output when armed though. I thought the way I wired it it would be energized when the alarm was OFF because the starter kill wires are grounded when DISARMED.....
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Matt
Posted By: iimm_Matt
Date Posted: June 29, 2002 at 7:19 AM
One more thing to clarify: when I have the scanner hooked up to my starter kill wires, it is ON when the alarm is DISARMED and OFF when the alarm is ARMED. ------------- ------------
Matt
Posted By: mobiletoys2002
Date Posted: June 29, 2002 at 7:53 AM
what kind of alarm is this that you are hooking up the scanner to,and what color is the wire that you are connecting the yellow scanner wire to. post back with info
Posted By: Velocity Motors
Date Posted: June 29, 2002 at 7:59 AM
Hey Matt, do you have a light tester ? If so, place the light tester clip on a ( - ) ground and then place the probe end on the starter kill wire from the alarm. Now arm the system, if the light stays on, then you have a ( + ) output starter disable wire. In this case you will need to wire a relay to convert the (+) signal to a ground signal that the scanner can use. Relay configuration : - 86 & 87 : GROUND
- 85 : Starter Disable wire from alarm
- 30 : To scanner (-) Ground When On wire
Only wire a relay like this if the starter disable wire is in fact a POSITIVE output wire. If you tested this wire with your light test and the light did not go on after you armed it, make sure you have a good ground and test it again. If after the second test the light still did not go on, then you have a negative output starter disable wire. To test a ( - ) output starter disable wire, place the clip of the probe to a 12 volt constant source and arm the system. Use the probe and test the starter disable wire from the alarm and the light should go on. ONLY do this after you have done the test above to verify that you have a ground output on the starter disable wire just to be sure. ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: iimm_Matt
Date Posted: June 29, 2002 at 12:38 PM
It's a "Ford" dealer-installed alarm.... crappy yes but all it's got for now. Should I do these tests on the "Key" side or the "motor" side?
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Matt
Posted By: iimm_Matt
Date Posted: June 29, 2002 at 1:13 PM
OK, I think the starter kill just breaks the circuit. When I tried the light bulb test on the "key" side of the alarm while it was disarmed, the starter turned over. When I tried it there with the alarm armed, nothing happened. When I tried the light bulb test on the "motor" side with the alarm armed or disarmed, the starter turned over. Could it be that the starter motor rests at ground and the alarm is just breaking this circuit??? I really, really, don't want to wire the scanner so that it just comes on when the car is off.... HELP!
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Matt
Posted By: iimm_Matt
Date Posted: June 29, 2002 at 7:38 PM
Someone PLEASE help!
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Matt
Posted By: Velocity Motors
Date Posted: June 29, 2002 at 9:59 PM
Hey Matt, you don't want to tap into the starter wire at all for this curcuit. The wires that you are testing for the starter disable relay would be pin # 85. This wire you will need to attach to another relay in the configuration that I had posted a few posts ago. Also, you better watch out with that probe and using 12 volts to test wires.... your going to burn something out. Always use ( - ) first to test wires. If it is indeed a 12 volt wire then verify it's circuit by placing 12 volts to it not the other way around. ------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: iimm_Matt
Date Posted: June 30, 2002 at 9:49 AM
What do you mean? The akarm has a built in relay, I guess, because I can't find a relay anywhere....... ------------- ------------
Matt
Posted By: Velocity Motors
Date Posted: June 30, 2002 at 10:25 AM
You wrote : " I've tried wiring it through a relay, with the starter kill wire on 85, +12 constant on 86, ground on 30, and the activation wire on 87a. THIS DOESN't WORK!!! why?????? How can I do this?" Use # 85 on this relay that you had from your first post and then attach to another relay in the configuration : 86 & 87 : GROUND 85 : Starter Disable wire from alarm 30 : To scanner (-) Ground When On wire------------- Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: iimm_Matt
Date Posted: June 30, 2002 at 2:19 PM
OK, I'm going to try this now...sorry I'm having such a hard time, it's really the first time I've dealt with anything like this (meaning relays...) Thanks for all the help... Just to clarify I'm going to take the starter disable wire and put it on pin 85, put ground to 86 and 87 and the scanner wire on 30.. right? ------------- ------------
Matt
Posted By: iimm_Matt
Date Posted: June 30, 2002 at 3:43 PM
OK, I went and bought a light tester, and found out that the starter wire doesn't put out 12 volts when armed......It is grounded when DISARMED, and not when armed, but doesn't put out 12 volts....so how can I wire a relay so that the starter wire provides ground (therefore energizing the coil) which would switch off the scanner, then when the ground is gone the coil is at rest and the scanner would come on because it would be on the normally closed pin on the relay..... that makes no sense but hopefully someone understands..... Thanks!
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Matt
Posted By: iimm_Matt
Date Posted: July 01, 2002 at 7:58 PM
OK, I wired a relay as in my last post and it KINDA works.... if you touch a ground to the side that the starter disable is connected to, the LED shuts off... It will then stay off until you arm the alarm, and then come on as it should.... The only thing is that it doesn't turn back off when you disarm the alarm.... any help? ------------- ------------
Matt
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