Hey guys, posting this in this group, in case someone with a 7.3 Superduty has done this before. I'm having trouble getting my 4x4 lights to work on my cluster. For background my truck started out as a 2wd 2002 7.3 Excursion. I have installed a manual transfer case in it. I'm trying to get the cluster to show the 4x4 lights when the transfer case is shifted into 4HI or 4Lo. I've got the pigtail plugged into the transfer case and have tested that when it's shifted into 4Hi it grounds out one pin and when shifted into 4Lo it grounds out another.

I've gone through the harnesses and have found the following:
The cluster harness does have the Brown/Yellow and Light blue wires, which are supposed to be the wires used for activating the lights. I read on another post where a guy said to simply tap into those wires with the transfer case wires and the lights should work. That does not happen on mine. When I put ground to those pins, nothing happens. I found pigtails above the glovebox where the 4x4 module would go and on one of those pigtails are the same brown/yellow and light blue wires. I'm assuming those are meant to go directly between the 4x4 module and the cluster, to illuminate the lights.

I do have another 2002 Excursion 4x4 parts truck that I've been trying to use parts from as I need them. I pulled the 4x4 module from it and plugged it in. I scanned the modules with my scanner and the truck now recognizes a GEM module, which is technically the 4x4 module, however that module now has a bunch of codes, as its missing the connection with an auto shift transfer case. I'm not sure if trucks that had a manual transfer case from the factory had 4x4 modules? On the wiring diagrams, it appears that they did not.

I did connect directly to the cluster via my scan tool and commanded the 4x4 lights to come on to verify that they work, and they work fine.

So my question is, what else can I try? Is the VSM or the PCM any different between 4x4 and 2wd trucks? I do have the VSM and the PCM from the parts truck available that I can try. I just don't know if any programming is required. I know people have had to get the dealer to programmed used VSM's when theirs fail, however the two Excursions are pretty much identical, one is just a 4x4, so the options should be the same on the VSM's, except for maybe the 4x4 option?

Some also mentioned that one of the 3 plugs in the engine bay that connect the body to the frame is supposed to have those two wires for the transfer case lights. I checked on my truck and I do not have those wires. I'm assuming it's because Excursions never came with a manual transfer case, so the under hood harnesses are slightly different.

Any input would be greatly appreciated

 

Quick update, I figured it out. Had to change the As Built programming on the cluster. I checked the cluster from my 4x4 parts truck and tried grounding out the Light Blue and Brown/Yellow wires and the lights worked on that cluster. So I figured it must be a programming issue. Luckily it’s very simple and only has one line.
My original 2wd cluster the line was 8980-000-FF69
the 4x4 cluster the line was B980-0000-FF99.

After I changed the programming on my 2wd original cluster to match the 4x4 one, the lights started working! There may be another change there as the 2wd cluster is a MPH cluster and the 4x4 cluster is a km/h cluster, but since I don’t know what the hex values actuslly mean, I just copied it to match the 4x4 cluster

 

Good job. Sounds like you have this stuff wired, no pun intended. When you get bored swing by and figure out why my 99's 4x4 doesn't work anymore.

 

glad there was a fix, when I converted my 03 to 4x4 i never heard of forscan or as built. it was 2010 though,
lived for many years with no 4x4 light.