how to test negative output on rs?
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=120054
Printed Date: July 09, 2025 at 7:42 PM
Topic: how to test negative output on rs?
Posted By: sniperess
Subject: how to test negative output on rs?
Date Posted: February 11, 2010 at 10:36 AM
I want to simulate a button push so I can turn on my rear defogger/defroster. It's a momentary push button switch in the control panel which communicates with the ECU and triggers some relays and stuff. I figured the safest way to not mess with the ECU wiring and everything is to have a relay "push" the switch, as if I manually pushed it.
85: AUX output on RS (-12v @ 250mA)
86: +12v
30: one side of switch
87: other side of switch
my logic is if I pulse on AUX output, it will energize the coil and 30/87 will short momentarily, as if I pushed the button.
So I wired it up and everything, but doesn't seem to work. I tested my relay by using a different +12v/-12v to energize the coil and it worked, it "pushed" the button.
How can I test that my AUX outputs are working? I'm not sure what setting to set on my multimeter and/or where to put the probes.
I got the system installed at a shop, just want to hook this AUX up myself. Little bit of learning is good, plus it will allow me to further customize later on (when it's warmer).
I have a 2009 Mitsubishi Lancer with CompuStar CM5200 alarm/starter.
Replies:
Posted By: x1le
Date Posted: February 11, 2010 at 11:01 AM
red prove to 12v, black to aux wire. When triggered, voltage should drop to 0.
Posted By: tedmond
Date Posted: February 11, 2010 at 4:08 PM
shouldnt voltage be 12v when triggered? red to constant 12v, black to (-) aux output from compustar. when aux is activated, dmm will read 12v. ------------- Ted
2nd Year Tier 1 Medical School
Still installing as a hobby...pays for groceries
Compustar Expert
Posted By: tommy...
Date Posted: February 11, 2010 at 4:59 PM
What unit is it...Are you using the correct wire...or on some units you have to press and hold for 3-5 seconds to activate aux... Oh and use the direct current setting...Normally a straight line with 3 dots underneath...The normal switch setting is 20v...
------------- M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
Posted By: x1le
Date Posted: February 11, 2010 at 5:35 PM
tedmond wrote:
shouldnt voltage be 12v when triggered?
red to constant 12v, black to (-) aux output from compustar.
when aux is activated, dmm will read 12v.
you're right, i'm not thinking 
Posted By: sniperess
Date Posted: February 11, 2010 at 6:51 PM
It's a CompuStar CM5200 alarm and remote starter. I got it installed at a shop, and I DO NOT have an OP500, but I was playing with the programming menus with 2-way remote. Do I need OP500 to activate the AUX?
Posted By: sniperess
Date Posted: February 11, 2010 at 6:57 PM
so... it should read 0v until AUX is activated? Anyone know what settings I should use? I have the programming tables and all.
Posted By: t&t tech
Date Posted: February 11, 2010 at 7:24 PM
Yes the meter should read 0 volts when the aux is inactive, and twelve volts when the aux is activated! The programming, someone else will assist there!
------------- COMMIT YOUR WAY TO JEHOVAH AND HE WILL ACT IN YOUR BEHALF.
PSALMS 37:5
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