Stock Reverse light circuit sensitivity?

[parb]

I tapped into the reverse light circuit for my leitner chase lights. I use a relay to protect the circuit from high current.

I've noticed that both the reverse lights and my additional lights come on but after a second or two the reverse lights come off. I have both my wolfbox and my chase lights tapped into the same circuit for the reverse light detection.

My theory is that the control box for the reverse lights is measuring current draw and is turning off the reverse lights due to to high current consumption. A protection mechanism. It is speculation though based on sewing this behavior on the headlight circuit when current went up and the display threw an error message.

I think the relay consumes 160mA and it's just about the only thing I can think of that explains the behavior. I'm going to remove the chase light relay control to verify this.

There is nothing else wonky going on? Nothing screwy like the reverse lights using pwm signaling or something like that?

Have people been successful hooking up relays to lights in our cars, or is it just me getting challenged?

I'm going to try a flyback diode across the coil to see if it's coil noise making the circuit misbehave.
If that doesn't work then I think I'll have to try to a pfet transistor to get a high impedance control signal for the relay to reducw the current draw on the brake light circuit.

I have yet to see automotive ssr relays but maybe I just haven't looked enough?

Or maybe just tap into the trailer brake circuit, it should be designed for higher current applications.

Anyone else been playing with lights and relays? Found anything unusual?

 

[RyanT]

Hey Parb,

How have you gotten on with this?

 

[parb]

Thanks for pinging me. It's user error.
I wired the additional lights directly into the reverse light circuit and the extra 1A of load was too high. Wired in the relay correctly with diodes to prevent reverse current to the backup lights in case I use the switch.

It's all good right now.
I can make a diagram for how to wire if it's helpful.
The backup light circuit definitely needs a relay, higher current results in the lights working for a few sconds and then turns off.

Hot tip, test for 10-15 seconds or so. I tested for just a few seconds and that was a mistake.

 

[RyanT]

That's good to know, thanks for sharing!