Installed a keyless remote car alarm to my 83 300D. I am amazed on my well it works on a 26 year old car. This is what I did:

1) Fix all the doors vacuum actuators, make sure I can central locked everything.
2) Installed an actuator on the driver's door to control the vacuum switch.
3) Hook up all wires to left/right running lights.
4) Hook up door wire to driver's door only. I cannot find a signal for all the doors open/close signal.
5) did not bother with starter kill relay.

The central lock will operate approx 10 times until the vacuum tank is exhausted.

Question: Anyone can advise on how to hook up door signal centrally without using diodes to combine signals?

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.