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Low Voltage Relay Noise

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grey ghost 
Member - Posts: 1
Member spacespace
Joined: April 11, 2022
Location: Florida, United States
Posted: April 11, 2022 at 8:03 PM / IP Logged Link to Post Post Reply Quote grey ghost
I have a 2004 BMW Z4 2.5i, on which I installed some aftermarket DRLs. It is simple enough to wire them with an accessory wire signaling a relay, but I am not simple. I decided I wanted them to turn on when I unlock the car, but my car doesn’t have a factory alarm system, so the other lights don’t flash. This was also not too complex as I found a wire inside the Central Locking System module that gives a signal for about 20 seconds after unlocking the vehicle. So I wired two relays to the lights, one triggered by an accessory power and one triggered by the locking system wire. So far this is all within my capabilities.
The issue that has arisen is that the locking system wire doesn’t shoot straight to 12v when the car is unlocked, it takes 1-2 seconds to build up to 12v. My multimeter shows it increases incrementally for that 1-2 seconds. This caused the relay to make a very distinct buzzing sound while the power builds, and it is quite unnerving.
I have 2 possible ideas to resolve this issue, but both are not things I have much experience with. I believe I could run a diode straight from the Central Locking System to the lights, which would prevent backfeeding the locking system with the other relay (from the accessory power). The other idea is some kind of way to filter out the lower voltages from getting to the relay, not sure if a capacitor could achieve this or some other way of only letting 12v+ to reach the relay.
Any ideas are greatly appreciated and any information on diodes or capacitors, if I’m mistaken on what they’re capable of let me know.
I can try to draw some diagrams up later and post them maybe tomorrow.
Member - Posts: 9
Member spacespace
Joined: April 13, 2022
Location: Ontario, Canada
Posted: April 13, 2022 at 3:08 AM / IP Logged Link to Post Post Reply Quote hav007-roco
Take Lock unlock directly from switch in center. Depending on the unit I belive you double up arm/disarm and connect to 1 wire from switch connect.
Rocky Verma

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