82’ Mercedes Keyless Entry Install

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=65726
Printed Date: May 13, 2025 at 2:54 PM

Topic: 82’ Mercedes Keyless Entry Install

Posted By: jamesdean
Subject: 82’ Mercedes Keyless Entry Install
Date Posted: November 06, 2005 at 6:42 PM

hey everyone

i have decided to invest in a keyless entry system in my first generation w126 Mercedes 300SD. It has vacuum powered locked run by a pump in the trunk. I bought the Valet 712t from Circuit City for $60.

I am having a little trouble install it. I have it wired up to the vacuum pump in the spare tire well. There are three wires on the plug for the pump...
ground...
yellow-12v (when unlocked)...
blue-12v (when locked)

I have 6 lock/unlock wires

Violet - unlock #87 normally open (input)
Blue/black - unlock #30 common output
BROWN / black - unlock #87a - normally closed
violet/black - lock #87 normally open (input)
WHITE/ black - lock #87 normally closed
GREEN/ black - lock #30 common output

I have it wired like this:
posted_image

Now, when i press the unlock button..the pump will cycle..unlock the locks but then keep running and re-lock them

when i press the lock button nothing happends.

can Anyone help?

Thanks

Kris

Replies:

Posted By: jamesdean
Date Posted: November 06, 2005 at 7:32 PM

i have also tried this method of wiring:

posted_image

it worked but only for either locking or unlocking.

Posted By: jamesdean
Date Posted: November 06, 2005 at 7:33 PM

my first method of wiring would work but the polarity on the one wire is wrong..its -12v and i need +12v

maybe this was a waste of my $.

Posted By: jamesdean
Date Posted: November 06, 2005 at 9:00 PM

never mind...i discovered that up until 1985 there was no actuator in the driver's side....it would be pointless to install a remote locking system that only could lock 3 doors.

Posted By: jamesdean
Date Posted: November 07, 2005 at 8:08 PM

OK I just recently found out that I can add an electric actuator to the driver's side door and make this work.....I just need (a lot of) help wiring up this unit to the vacuum pump. I turn to you guys..as i am no expert in this field. I have understanding--to a certain degree but nothing as much as the professionals.

Thanks again.

Kris