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Remotely Open Sliding Doors With No Relays

5953 Views 6 Replies 5 Participants Last post by  xenon2000
Wanted to post my latest Odyssey project in hopes of helping someone wanting more options. I found several diagrams for controlling the power sliding doors using an aftermarket remote, but they all involved several relays and some timing modules. They all basically used the same wirings that are located at the back of the rocker switches on the dash but in slightly different ways. I did not like any of these solutions and came up with my own. My thought was I would use the same logic that the factory keyless module uses to trigger the door to open and close.

I started the project by reverse engineering the way the factory keyless worked and it turned out that it was a little more complex than just grounding a wire. I connected a logic analyzer to the wire from the factory keyless and got a two pulses of 0.3 seconds on time and 0.06 seconds off time. I attached an output of this diagram where channel 1 is the Grn/Blu wire that triggers the door and channel 2 is the Grn/Org wire that gives the status of when the door is in motion.

To recreate these 2 pulses I designed a circuit that uses two 555 timers. The first timer(U1) is a monostable and will turn on the second timer(U2) on when power is applied. The first timer is just long enough to only let 2 pulses out of the second timer. The second timer is an astable. The PNP transistor(Q1) is important because it will only apply power to the timers when grounded for the duration of the 2 pulse cycle. This design characteristic gives approximately no current draw when off. It only draws current(<20mA) when timing.

It is important if you make this circuit you may need to change the values of R2 and C1 if they do not work for you. There are many variables and I had to tweak these last minute after I finished. If set properly you should only get 2 full pulses. You can clearly see this with the LED connected on the output which is an excellent debug feature.

One limitation of this design is it only allows my one AUX output to control both doors. I have made a compromise just before I finished and added a switch that allows either door or both to be selected. I have it set to driver side door now and when more kids come along I will set to both doors. Keep in mind if your remote has multiple AUX outputs you can build two of these circuits and have full control.

For the connections you will need to find a Grn/Blu wire for the driver's side door and a Grn/Blk wire for the passenger's side door. You need to monitor the voltage on these with a DMM to watch if the voltage goes to 0V when you operate the door. The door lock wires share these colors and are on the same harness.

Hopefully someone else out there would also like to have a solid state design like this and try it themselves. I would be happy to answer any questions.

Application should be for 1999-2004 EX models.


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