I'd like to start by apologizing for my first forum post being such a long read. But I felt it necessary to give a full understanding of this ongoing issue...

Okay, so where to begin. Guess I'll just start from the top.
I've been working on a 99 Ram 1500 Conversion Van (Mark III) for my mother who recently inherited the truck from her previous employer whom was a quad that she cared for, for over 20 years, and he has now passed, leaving her the Van which is crazy clean garage kept under 100k mileage grocery getter.

I, being the good son I am, offered to do some minor repairs and upgrades for her over the mother's day holiday, primarily consisting of fixing the passenger window that wouldn't go up, that grew into doing both doors just because. Then doing a front to back, top to bottom, lighting upgrade converting the old incandescent to LED's inside and out. I installed Alla leds everywhere, coupled with load resistors on each corner to prevent any hyperflashing turn signals. Then moved on to the inside. Which I should mention has had significant upgrades done to it through the years, hardwood mahogany floors, entertainment center removed opening up the the cab ceiling, and several additional interior lights added throughout. All of which received new led's, 16 in total. Along with the instrument cluster and dash panel controls.

Then came the big reveal, and the even bigger surprise afterward once I realized that everything worked beautifully, everything that is, except the dome lights. ALL 16 of them were a no glow for the big showing. Head in hand, I reassured my mother that it was probably nothing major and I'd fix it the next day.

That was two days ago, and I haven't let up on that thing trying to figure it out. I have once again dismantled practically everything inside the Van and for the life of me just can't figure out what has failed and or how to bypass it. So here's a running list of things I've gone through and tried while troubleshooting this issue.

So for starters, my interior cluster and dash lights do work properly, dim etc. but turning the switch to full stop does not result in the lights being turned on overhead, and same goes for the door triggers. So I started with the obvious things like fuses. Checked the panel on the left side of the dash, and all ok, then moved under the hood, still no issues found, then on to the rear panel that the conversion company installed, and it was there I started seeing some oddities. The fuses were infact all good, but it was the onboard relay this panel had that I noticed was not activating.

I proceeded to start checking all the door triggers, and everything was checking out fine with a multimeter until I got to the passenger front door, which I apparently missed plugging back in while re-assembling it. Sadly though it did nothing to assist in fixing the no lighting issue. ..

So I then proceeded to inspecting the PCB were the relay of question was affixed, but again the multimeter came up empty and I was no closer to figuring this thing out. So I decided to attempt a bypass of said relay, and finally I got some favorable results, sort of. I did succeed in getting the lights on, by bypassing the onboard relay with one of my own, but that's where things quickly came unraveled again. Because of the door triggers reversing polarity NO/NC state, I found myself extremely confused on how to properly wire up this new relay that didn't result in the relay engaging with the doors and then not disengaging when the door closed because the triggers had swapped polarity, effictly locking my relay in its open state even tho the 85-86 pins were no longer powered.

So I once again tried to figure out the real problem, and soon noticed that with all doors closed, using the dimmer I could rotate to the ON position and the stock lighting relay would click on, so I begin checking each door trigger by opening the door, then turning the dimmer to see if it would engage the relay, and as it should be, each door prevented the override, all but one, the drivers door. So it being open did nothing in preventing the switch ON from triggering the relay. Indicating (I thought) that this must be the real issue. But opening the door up and checking the latch based door trigger for continuity it appeared to be functioning correctly. Latch closed = open circuit and latch open (ie. door open) = closed circuit. So once again I moved on, this time trying purely out of desperation, changing out the old switch for a new one. And once again, only disappointment followed.

And I think that just about brings us to the here and now. With me mentally exhausted and beat down by a vintage Dodge Van and hoping somebody, somewhere might somehow take the time to read my diary of defeat and despair, and maybe, just maybe offer up some insight that could result in this nightmare finally coming to an end.

TLDR: Interior lights wont work with doors or switch, all fuses OK, all options seemingly exhausted. HELP!

Solved: Jump to conclusion

 

That's part of the fun with working on conversion vans..... The factory documentation no longer applies..... So, tracing circuits and such gets really challenging......

Do the various switches and such merely supply the ground path for the relay control circuits? Or do some supply ground, and others supply power??

 

Well the door triggers are a bit odd, in that one side of the two wire arrangement is supplying + power and the other wire is neutral while the circuit is open, but when closed the neutral switches to ground and the + supply wire also switches to ground. The trouble comes into play when you try to use any one trigger as a access point into the trigger system, because only one of the two wires available actually ties to the other triggers, and of course it's the + - polarity changing one.

Altho now as I'm sitting here breaking it down in my head to explain it, I realise that if I were to just use the neutral wire from every trigger and diode isolate them to prevent cross talk, I think I could recreate a usable circuit that would at least toggle the lights with the triggers. But I wouldn't have the first clue how to include the dash switch override that prevents the lights from being on. The On toggle would be fairly straightforward because I did locate the wire on the switch that goes to ground when it's toggled, so it'd just be another diode isolated trigger along with the doors.

So yeah, if anyone might know how I could configure my relay to include the power override function I think I might just be able to fix this thing.
Thanks for your reply, it was more helpful then you might of first thought!

 

Hhhhmmm..... The switches should just complete a circuit, my *guess* is, that one wire will have 12 volts, and the other goes to ground, so, closing the switch completes the circuit, and triggers the relay.

 

Thread update, I did eventually work around the problem in a roundabout way that did finally result in a fully functional interior light. What I did that lead to that was bypass the onboard lighting relay with one of my own. Then to maintain the dome override function of the main switch I added one more relay with it's NO/NC state wired so that it rested on 12v that in turn feed the other relay it's 12v. So when the override was triggered the first relay would switch on toggling over to an open pole thus removing power from the door triggered relay.

Funny enough, it was in my doing that which lead me to discover the root of my entire problem. And that turned out to be the stupid dome override built into the main switch was overriding the lights the entire time, even tho it wasnt toggled to do so. So yeah my fight wasn't with the OE relay, it was the OE override! And I had no way of knowing that, until I had created my own circuit to handle its signal. So in the end I just left my new relay on the door triggers and then added a simple toggle switch at the dash that the trigger signal passed through, so if I did want the doors overridden, toggling the switch would effectively disconnect the trigger wire from the relay, resulting in a controllable lighting that only slightly deviated from the original systems controls.

My pride was a little wounded by the amount of time it took me to land at the finale conclusion, redeemed only by the fact that I did eventually solve the problem.
So if anyone were to encounter this thread in the future and try to glean some insight from it, I'd say to them: When there's no obvious reason the lights wont work, Start troubleshooting at the places that have the ability to turn off the lights (ie. triggers and overrides) , and work backwards from there. Might just save yourself some headaches and time.

Thanks for your feedback, hopefully fingers crossed this will be the last you'll see of me.... At least of me being the help'e instead of help'er

 

The important things are: 1: It now functions as you intend, and 2: you learned something. That sounds like a WIN in my book.