New-to-me 2005 E350 Club Wagon, full factory headliner with overhead lighting. I did not receive a factory key fob with buttons so can't really determine if the RKE is present or activated. (There is no separate RKE module present, not the type on my 2003 E250 with PDL, PW etc.) I'll be installing an aftermarket relative low-tech alarm with PDL activation, naturally this alarm is triggered by the dome light door switches. When any door is opened then closed the dome light stays on for a timed period interfering with properly activation of the alarm. Naturally once the dome light has timed out the alarm would works perfectly but I'd prefer to not be forced to wait for the dome light to extinguish.

Is there any relay or other device responsible for this event or is it all controlled by the Vehicle Security Module? If that module's the culprit is there a way to deactivate it through the ECM at the dealer level (or with something like AutoEnginuity software?

TIA

 

The diagrams show the door switch inputs going to the instrument cluster. I didn't keep looking, but probably the instrument cluster communicates over the communication network to the body module which more than likely drives the light bulbs themselves.

How does this alarm system work? Do you have a key fob that arms it? Why do you need the domelight to arm the system? What if you close all the doors, the domelight goes out and arms the system, and then you turn around and need back in? You have a keyfob to disarm the system? Do they not want the system to arm unless all the doors are shut? Is that the reason for the domelight thing?

The reason I am asking, all the door switches are grounding switches. I believe they ground the wire going to the instrument cluster to turn the domelights on, and tell other things the door is ajar. If you wanted to experiment, and the cluster was not too bad to get to, could you wire a relay in, put a hot wire on one side of the coil, and put the door switch wires on the other side of the coil with diodes so they would not cross-talk. Anytime a door opened and grounded the coil, the relay would pick and you could hook it's contacts to your alarm system.

 

This alarm is completely independent, a self-contained device that is armed/disarmed by its own RF transmitter remote(s). There are three separate grounding switch inputs available; I use only one of those and it's tied to the dome light. Once armed the alert will sound if the dome light is turned on. This alarm has a PDL feature that is tied into the circuit powering that feature through the door lock/unlock buttons.

FWIW if the dome light is on the alarm will not arm---this is why the delayed off is an issue.

Your idea about tying into the door switch wire leading into the cluster makes perfect sense---I'll give that a try as its not that hard to access the cluster rear-mounted wiring connectors. IF the signal leading into the cluster works 100% in sympathy to the dome light switches on the door jambs that would be the perfect solution.

This is an image of the alarm "brain" and its available connections:






Thanks Franklin---good points you raise.

 

This is where I went to get the diagrams. BBB Industries- Premium Alternators, Starters, Power Steering Products | TSB's & Wiring Diagrams

They make you fill out a form now before they let you in, but it has never amounted to anything. I emailed them and said I would like an account, they brushed me off and said they were not set up yet. So I just have to fill out the form each time I want to go in and look something up.

 

Looking at the instrument cluster connector C220b there are two circuits that might figure into this delayed off dome light situation, #1004 & #1008. For now I'll pull the cluster out and probe the two connectors (C220a & C220b) to see if there is a direct feed from the door switches that don't work through a timing relay.

If I find something there I'll be able to connect my alarm that'll still be activated upon a front door opening. I don't really need the side or rear door switches to trigger the alarm as I'll be installing electronic dead bolt locks that are engaged/disengaged by the alarm.

 

So if anyone's interested I've solved this problem somewhat easily. Following the EVTM's schematic I found three points the door triggers and main light switch call for dome light illumination. Removed the actual cluster, probed those points on the cluster connectors discovering I had continuity to ground at each point appropriate to doors opening/closing and full counter clockwise rotation of the headlight switch ****.

From here I'll use a single relay which can be triggered by any of the three inputs which will send power to the only dome light above the front seats. Rear lighting will be on a completely separate electrical feed and switches mounted in the front cabin and one each in a side door and another in a rear door.

Thanks to Franklin for an earlier "lesson" I confirmed the schematic with my actual van, not relying on wire color alone. In fact one wire marked as Rd/Pk looked entirely red until a different light was used. Even then the difference in color was so slight it could have easily been missed.

Thanks again all----the help here got me to a solution!

 

I would make sure you use diodes or 3 separate relays to hook the 3 single inputs to one input. If you tie them all to one relay, that means they are also being tied to each other, and that may foul things up. One switch grounding will ground all 3 inputs at once.

 

There were my thoughts as well----since the inputs I've found lead into the cluster's microprocessor I don't want to interfere with its operation. I'm guessing the calls for dome light most likely are a separate part of that microprocessor but won't take a chance.

At bare minimum diodes will be in-place, relays a very strong consideration.

Thanks again Franklin!

So an update if its of interest to anyone.........

Tapping into the door switch trigger wires (2, one each for left front and one for right front, right side hinged doors and rear doors) and main headlight switch leading into the cluster I was able to join all three into a single grounding connection which powers a small relay. This relay then feeds the only dome light left, mounted above the front seats.

There doesn't seem to be any ill effects, the dome light working 100% in sympathy with doors open and closed. FWIW another reason apart from the alarm being armed this was necessary is working out of the van with doors constantly being opened and closed the dome light and its control module would experience much higher than normal usage, something else I won't have to fix in the future.