Weird relay problem

My thought kind of mimics auex.  If there's not enough current to trigger a relay, there's not enough to trigger that kind of relay regardless of whether the relay is being used in a "traditional" or polarity reversing role.  If someone knew of a relay that was designed to trigger at much lower currents than "standard" SPDT auto relays I might try that.  Otherwise, it's getting cold, I'm sick of lying on my back under the dash, and using the 3rd aux output more or less takes care of the issue.

Thanks guys, it was a learning experience and I owe both of you a big thank you!

In regards to not enough current to trigger the first relay why would it trigger "booster" relay? Hey it can be true and is. In fact I have seen many scenarios where one didn't work but two did! Not all relays are the same but we hardly see the different wierd ones when we are working with aftermarket stuff. I have worked with all kinds of brand of relays and have found that some will engage the coils with as little as 100ma and others don't budge untill almost 500ma. Most systems are designed to push a relay of about 300ma (a number you've probably seen many times in wiring manuals), however there can be a deterioration of that output over time. And once again I speak from experience. Although somewhat rare you may see a vehicle who's locks or "other" worked fine for a few weeks or even a few months to only find its way back into your shop. The average tech will swap out the unit and all is well. The educated tech will want to investigate and soon they will find that although they still see an output from the unit it seems to be a little short of the mark. So they add an "amplification " relay (the proper term) and Ta Da everything works great again.

So Brian, since you have already changed relays (by the way you don't need to change the wiring, either way is O.K. for this application) the question is did you end up going up in amperage or staying the same? Is your output deteriorated to the point of no return, or can you step down to a lower amperage and get things to work again?

There is one other  thing you might try---a spike diode across the coil. Place a 1 amp diode with the cathode (stripe side) attached to the 12V(+) on your coil contact and the anode (long side) to the negative trigger wire from the unit where it connects to the relay. I know it looks like it doesn't do anything this way but it is correct.  

I can't say for sure why your lights stopped flashing, all indicators say they shouldn't have. The last thing you might do (not to offend) is check your connections. Not just visually. I have techs who tell me "yeah I got 12V going to my line", or "yeah my door wire is connected", but they never put their hands on the lines or pull them off to check physically the contact they believe they have. Most fixes are usually the easy overlooked item so don't give yourself a headache thinking too much into this. Look for the easy stuff. Let logic prevail. 

sometimes dei units fry the terminal coming out of the module, pull the white wire ( pin and all ) out of the module, use a small screwdriver to scrape any residue of the t\module terminal, then take and unplug any of the other wires in that harness that is not being used and remove it and put it in the parking light slot and give that a try.

The current (~6ma) measured with your multimeter while it was in series with alarm output is not the max achievable current of this output.  That was merely what was being drawn at that moment.  Current only draws what is required, so at any given time the measurement is going to give a reading which reflects what the output's connected device is doing......So if you measured this wire open or even through the coil of a relay it is not telling you that 6ma is all it puts out.

I read all posts twice and I have been wondering ...Do you also have Parking lights hooked up to this wire?  If so, do they work?  Also......what is the jumper on the DEI unit set at (-) or (+)?  or is the jumper missing?  (That is what I suspect might be the problem.)

If you have more devices (lights, or relays) hooked up to this wire, you need to isolate them from each other using diodes.

Good Luck