Compustar Issues on Sierra
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=87943
Printed Date: July 06, 2025 at 10:31 AM
Topic: Compustar Issues on Sierra
Posted By: twister4399
Subject: Compustar Issues on Sierra
Date Posted: December 28, 2006 at 4:41 PM
First of all thanks for all the advice this site has given me.
I am installing a 2W900FMAS on a 99 GMC Sierra. I am a first time installer but took the time to check all the truck wires before I got started with a DMM and soldered all connections. The problems I am having is that the remote start feature wont start the truck the fuel pump and all accessories turn on but it does not turn over. After checking the yellow output wire to the starter kill there is no voltage sent down this wire (possible bad brain?). The other issue is that the system will arm and disarm but the doors on the truck do not lock and unlock after checking the voltage at the brain for the + outputs for both lock and unlock there is nothing. Is there any suggestions before I ask the seller to exchange me brains.
The truck starts fine with the key and when remote started the security light doesn't flash so I am pretty certain the 555LW is hooked up correctly.
THANKS
Replies:
Posted By: twister4399
Date Posted: December 28, 2006 at 4:44 PM
Also if I start the truck with the key and have the remote start take over I can pull the key out and the truck runs fine. Hope I left enough info.
Posted By: JWorm
Date Posted: December 28, 2006 at 6:40 PM
The unit does not have (+) doorlock outputs. You either need to use a polarity inverter, or relays.
Did you learn tach?
Posted By: twister4399
Date Posted: December 28, 2006 at 9:33 PM
The wiring manual says it has + locks and yes the tach learn was done the siren chirped once after the button was pressed.
Posted By: JWorm
Date Posted: December 28, 2006 at 10:19 PM
Is it a CM3000a brain? Is so, it only has (-) locks.
I believe older units had (-) and (+) doorlock ouputs, but ones made in at least the last year have only had (-) outputs. I only started dealing with Compustar about 14 months ago, so I'm not sure when they did away with the (+) lock outputs.
Posted By: twister4399
Date Posted: December 29, 2006 at 1:25 AM
Well I just bought it but I think it might be an older unit because I was getting an error for reservation mode and when I popped the cover off there was the jumper that needed snipped for the automatic. I will check for a negative output tomm. if thats the case ill pick up some relays to change them to + output. Any thoughts on why there is no power from the yellow wire on remote start? I contacted my seller and they said they will warranty it but I probably wont be able to get it in the mail till next weeks so I will try and mess around with it.
Posted By: twister4399
Date Posted: December 29, 2006 at 10:20 PM
Ok got the relays for the locks and the remote start to work. Something in the programing was wrong I went and set it up to factory defaults and the truck started right up. Only issue is now is that I cant get the ignition locks off the doors lock when i press on the brake with the key in the on position then unlock when I turn the truck off. I also think I blew a stock truck lock and unlock fuse or relay because the door lock switches in the truck do not work and the stock key fob only unlocks the driver door and flashes the lights when the lock is pressed only the lights flash.
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