SOLUTION: 4th gen Personal (aka Map) Light mod

rando · 2004-11-17T19:49:34+00:00

The narrative below describes how I mod'd my map lights to change their behavior, when switched, from ON/OFF to ON/DOOR. A new switch can easily be added to extend this solution to provide ON/(OFF/DOOR) functionality. This is a continuation of this thread with a more appropriate title so people can find it. If you make this modifcation to your truck you may damage your body ECU, start your truck on fire, or otherwise cause damage or injury to people, property, or the universe. The modification described worked for me but I cannot guarantee that it is safe or that it will work for you. By reading beyond this point, you agree to proceed at your own risk and accept full liability for your actions and their consequences. The information provided here is for informational purposes only. I do not endorse this modication nor recommend that ANYONE actually perform what is described. With the personal light assembly (a.k.a. map lights, sun glass holder, homelink, etc) removed from the truck, I removed the two map light switches. These slide out at either end of the assembly. Each switch is a two position SPDT type with 3 female contacts -- 1 contact is unused. What I did was tap the unused contact on each switch and wire it to the body ECU ILE circuit. This allows me to switch each of the map lights between ON and DOOR mode. When in DOOR mode, they now behave exactly the same as the back seat or storage area lights in DOOR mode. The first thing I did was add an ILE circuit extension to the personal light area. The easiest place to tap ILE is behind the driver's dash/door pillar (two screws). The roof wire bundle runs through there. Within that bundle is a white with blue stripes 3-wire ribbon. The center wire in that ribbon is ILE. Alternatively, the same wire can be tapped at connector 1A pin 8 located at the driver's side fuse panel. Either way I would have had to remove the pillar cover so it made more sense to just tap it in there instead of at the fuse block. I ran a length of wire from the tap point back to the personal light area (with connectors on both ends so that I can easily remove everything if needed). First fish the wire foward towards the rearview mirror, then over to the pillar, then tuck it back under the headliner. Next I needed to tap the personal light switches. This is easy because the switches plug in/out of the assembly. I used a short strand of 18G wire for each switch. One end of each wire is stripped back about 1/4 inch and pushed up into the unused switch contact. The switch is then plugged back in to the peronsal light assembly. I took some care to route the new wires such that they could not wiggle loose from the switch. I don't want them popping out and starting a fire, damaging my ECU or blowing a fuse. I should probably glue these down just to make sure they never move. The other end of the wires are joined to together into a connector that plugs into the new ILE circuit I added above. That's it. When switched to what was previously OFF mode, my map lights now turn on/off automatically with the rest of the interior lights. When switched to ON mode, they come on as long as the dome relay is active (original behavior). I don't really need an OFF mode but to add one I would just need to put an ON/OFF switch in series with the new ILE circuit. This new switch would be labeled DOOR/OFF and would work in conjuction with the built-in map light switches to provide an ON/(DOOR/OFF) capability. The biggest risk of this modification is that ILE circuit is now sinking the additional current from the map lights. Though everything appears to be working fine, it's possible that this may lead to premature body ECU failure or even a fire. Since the ILE circuit is protected externally by the 10A dome light fuse I assume (but can't be sure) that this circuit is safe. Adding the map lights adds about 1A to this circuit, probably still substantially less than 10A total. Then again, looking at the size of the ILE wire, it's hard to imagine that 10A can flow through there for very long -- who knows? A safer solution would involve a couple of transistors. PROCEED AT YOUR OWN RISK!!!!

Thread starter rando
Start date Nov 17, 2004

Denise James

New member

Oct 18, 2019

#101

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