relay behavior

Don't waste 1 diode across coil + to 86 and - to 85, band to 86.

I find the above ambiguous. I assume Howie means the (spike quenching) diode across the coil is not wasted. (IE - keep it even if it doesn't seem to help.) That quenching diode across the coil will need to be an 1N4004 or 1N4007 to be safe. The voltage ratings of 1N4001-4003 are generally too low. gargouille, when you say you have feedback, what problem is it causing? I presume you have #30 (else #87) to a +12V source; #87 (else #30) to your lights; #86 to the same or other +12V source, & #85 to the grounding alarm trigger?

I meant theOP is wasting his time, terminal 85 if used as the coil NEG will always show a POS. It's simply current through the coil diode and never advise anything but 1N4004 because it's the most readily available and it's PIV is enough to quench the relay spike.

My suspicion too, hence my what problem? question. IE - a voltage present on an open circuit is not feedback (it is a source....).

Bloody iPad my last post should read current through the coil. The only 1amp diode I use and never advise anything but.... Sorry about that.

hello again, as you can see on the picture, my test light gives me a positive feedback on the red wire that is connected to the wires that are sending the signal from the alarm CPU. the cpu sends a 200MA ground signal when activated. im using this as a remote activated light. my issue is that a +12 battery voltage is sent back to the cpu of the alarm . for clarity, the yellow wire is going to the device beeing lighted up, the purple and yellow/black are fused on +12v and the red receives the signal from the alarm cpu. thank you once again for your time. EricEric

Yes - that is quite normal. Unless the ground side of the coil (85) is grounded, it will have the same voltage as its other side (86) - namely +12V. That is not "feedback". It is simple circuit theory. Just make sure your relay coil consumes less than 200mA (ie, a coil resistance higher than ~70 Ohms).

Hook up your test light exactly like you have it in the picture above. The test light will be on. This is normal, and correct, for the way you have the relay wired. Activate your alarm trigger. The test light should go out while the trigger is being received. If it does, even just briefly, the circuit is working. I'm wondering if you're receiving a 'pulse' trigger, which is very brief, and you're not getting the activation you expect? Perhaps you are expecting what the industry calls a "validity trigger" which is where the (-) pulse is sent for as long as you hold the button down on the transmitter? If so, consult your installation manual for instructions on how to program this characteristic. I don't understand what the "problem" your experiencing with your circuit is. The difference between a pulse and a validity trigger is all I have for now. If this isn't the problem, try to explain exactly what your circuit isn't doing "correctly". Because the way it's wired, and what your seeing with your test light is correct. The anti-spike diode these guys are having you do has nothing to do with solving your issue.

Davep you're quite correct. I believe our OP has tested before trying, nothing wrong with that but lack of subject knowledge has given us the original question. And yes Davep I know you and I are opposite sides of the "to diode or not question"

I was thinking of high-resistance paths etc until Howie mentioned the spike issue. IMO that was brilliant - I have often seen problems caused by spikes whether thru the power distribution or inductive etc coupling across circuits. It should be obvious that because the OP mentioned "feedback", I assumed it was a feedback problem. It wasn't until later that I got suspicious. As to "2D or not 2D?" (2 diode or not 2 diode), I have certainly read & heard of many non-dioded disasters (and I have heard a few non-dioded kicks!) but I can't recall ever having issues. I am surprised however that some product instruct the use of diode protection "if" relays are to be driven. (IMO in that case they should be included in the product - especially when very few would drive anything other than relays! )