Avital 3305L Domelight Supervision

As noted, system is an Avital 3305L. The car is a production sedan with no stock wiring. The car uses negative grounding on the door switches. For various reasons I decided to run the dome lights off a relay with B+ to 30 and 86, output to all domelights on 87, triggered by 85 (-). A gentleman had previously posted about his Dodge Ram with a BCM that also switched ground on the built-in relay in the BCM. I believe it was decided that the door trigger and domelight supervision could both go to relay pin 85. If so, do I also need to diode isolate the trigger and supervision?

I probably didn't explain my issue too well. I'll try again, with a pic! I'm not sure if the alarm cares if it sees ground from both the door trigger and supervision on #3 and #5 at the same time. For instance, opening the door while the alarm has the dome light on due to supervision.

Your diode is backwards - the stripe needs to go to the ground source. Otherwise your diagram looks good. You might also consider installing a reverse biased diode across the relay coil. Just connect the striped side to 86 and the other side to 85. This will help protect from voltage spikes caused when the coil loses power.

Thanks, lee.lopez I tend to have an aversion to correctly installing diodes! I'll make sure all my relays (especially those going to EFI components) have the built-in diode.