2000 Lexus GS400, Compustar 900AS, Door Lock Relay?

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=146050
Printed Date: May 12, 2025 at 5:21 AM

Topic: 2000 Lexus GS400, Compustar 900AS, Door Lock Relay?

Posted By: tank181
Subject: 2000 Lexus GS400, Compustar 900AS, Door Lock Relay?
Date Posted: February 29, 2020 at 11:51 PM

Hey guys,
Sorry for the noob stuff I'm about to ask.

I am installing a Compustar 900AS into a 2000 Lexus GS400. I have a question about the door locks. after researching on here it looks like the door locks are "Type B" 3 wire (-) negative. The Alarm-R/S lock/unlock outputs both have 250Ma, 800mS negative (-) outputs.
Do I need a relay for the door locks?
Would wiring up the aftermarket alarm to operate the factory alarm in unison work with a relay on the door locks?
(seen here: https://bananags.grantham-international.com/GS_DIY/ALARM/index.html )
Lastly, would it be ok to wire the factory alarm arm/disarm outputs from the Compustar (negative (-) 250mA, 800mS) on the factory disarm wires with diodes?

Thanks in advance.

Replies:

Posted By: tank181
Date Posted: February 29, 2020 at 11:52 PM

The Vehicle has a transponder enabled immobilizer.

Posted By: djdeito
Date Posted: March 01, 2020 at 4:56 PM

what bypass will you be using with your compustar 900AS system?

Posted By: tank181
Date Posted: March 02, 2020 at 3:03 PM

Blade-AL

Posted By: tank181
Date Posted: March 02, 2020 at 3:24 PM

I have included some wiring schematics driectly from the OE manual on the door locks and door ecu for reference. posted_image

Posted By: djdeito
Date Posted: March 03, 2020 at 2:19 PM

The 1N4004 diode accross the relay pins 86 and 85 are necessary if you use a relay with no built-in diode protection. If you use a relay with built-in diode protection, note the polarity and wire the relay accordingly.

posted_image

Posted By: tank181
Date Posted: March 05, 2020 at 3:34 PM

Awesome, Thanks!

Regarding the previous post, will that configuraton allow the aftermarket alarm and factory alarm to work in unison? or will this configuration sort of "disable" the factory alarm? I am asking this because there are other functions tied into the OEM key fob (alarm) such as window and sunroof open.
(window/sunroof close is tied into the keyed door entry)

Regarding the following picture;

What do you guys think about this configuration? (see picture)
Will this type of connection work with an alarm/Remote start?
What can go wrong with this type of connection?
That connection was something that a person with an identical car did to make the factory alarm work with the aftermarket alarm he installed, but that was nearly 20 years ago.
posted_image