[sirfallsalot]

Aaaaahhhhhh!!!!! Does anyone have an actual wiring diagram of the interior lighting on a 2020 T250?

I've read a few threads about adding various switches and/or relays to change the way the silly cargo lights are controlled. In at least one of these threads it says that the lights are ground switched to turn them on/off, and that the 12V power is always on. Not true in my van. I measured power at the light itself, and the blue/white wire at the light is hot (12V). Black is ground. When I depress the pushbutton switch at back doors, the 12V blue/white wire at the light turns off (interestingly, the wires to the back door switch are blue/white on one side, black on the other. No idea what it's actually switching).

There is a 3-position switch at the cab light above the windshield. Here's how it behaves:

"O" position: The the cab/dome light is always off. Open/close the front doors and the cab and cargo lights both stay off. Open the cargo doors, or unlock the cargo doors with remote, and the cargo lights come on but the cab light stays off. Leave cargo doors open & light stays on for 30 minutes, then turns off until door is closed/opened (door switch activated), or unlock again with remote.

"I" position: both cab & cargo lights are always on, even after closing and locking all doors with remote. In this position they will go off in 30 minutes.

Middle position: all lights come on when passenger or cargo doors are opened. Leave the doors open and they turn off in 30 minutes. Close the doors & they go off in a few seconds.

Any time the cargo lights are on, you can turn them on/off with the switch at the back door. After they go off due to timer, switch at back has no effect.

So I have no idea how this thing is wired up.

What I want to do is have it work as it does above, but also be able to turn the lights always-off (no matter what), or always on (no matter what. Timer be damned. If I kill the battery it's my own fault).

After typing this, I think the smart solution is to use a DPDT 3 position switch:

• "O" position: always on (power and ground supplied directly from battery)
• "Middle" position: always off (power/ground disconnected)
• "I" position: stock config (power and ground supplied by existing wiring)

Then add a dimmer between switch and lights so that I can dim any time the lights are on.

Now I just need to figure out exactly where to cut the stock wires, and where to source the 12V (CCP I suppose).

Also, it would be nice to understand how the rear switch is wired. Will it still work after I install the DPDT? My kingdom for a wiring diagram!

UPDATE: I found a wiring diagram. See attached. For the 2020 T250 (148" med roof), there are 2 wires in the wiring harness running from behind driver to back of the van, that are white with blue stripe. Apparently both wires connect to the BCM. When the lights are on, one of the wires has 12V and the other appears to be floating at about 3V. If I toggle the switch the floating line is grounded. So, I believe that the 12V output is feeding power to all of the cargo lights under BCM control, and the other is just signaling to the BCM that you want to turn the lights off. I cut the wire with 12V, and cargo lights went off as expected. Now, I will install a SPDT on-off-on switch (3 connectors). To the left connector I will connect the 12V output from the BCM. To the middle connector I'll connect the power to the lights. To the third connector I'll wire 12V from the battery (fuse block connected to the CCP). Thus, the switch will allow "always on", "always off", and "BCM driven".

 

[tngw1500se]

The guy at ford who designed the cargo light operation should be fired. I just unplugged all 4 lights, covered the wires with tape and rewired them using two "3 way" switches and one "four way switch". They don't come on with any door opening but there's a switch in the step. I'm going to run them off the house battery.

I installed the step switch on the right side on the plastic step. If you remove the step, you'll see there's plenty of room behind it.

 

[GunnyR]

The guy at ford who designed the cargo light operation should be fired. ....

😂🤣😂

I've installed a house battery and in the middle of installing my own lights. I'll leave the factory lights in operation.... for the moment!

The other guy that has to go is the guy who engineered the cargo light wiring raceway clips. I've broken nearly all of them in the last few days. Stopped at my local dealer and they want $6.00 each for them!

Semper Fi,
Jeff

 

[me&z]

Aaaaahhhhhh!!!!! Does anyone have an actual wiring diagram of the interior lighting on a 2020 T250?

Disclaimer: I'm an ME, not a EE. Sparky stuff scares me.

I have, however, read all 435 posts on cargo lights more than once. As near as I can figure out, it all got changed for 2020. So the helpful information about adding a switch onto a specific fuse no longer applies. Not a solution, but at least explains why the information you've tried doesn't work. I think the cargo lights now run through the BCM (maybe, remember, I'm not a EE).

I just removed the middle lights completely. Easy to do. The clips are on the short ends of the lights and harness disconnects from the main harness easily enough. Eventually I'll probably get frustrated enough to take the rear light out too. Not there yet. Did I mention sparky stuff scares me?

 

[njvagabond]

Disclaimer: I'm an ME, not a EE. Sparky stuff scares me.

I have, however, read all 435 posts on cargo lights more than once. As near as I can figure out, it all got changed for 2020. So the helpful information about adding a switch onto a specific fuse no longer applies. Not a solution, but at least explains why the information you've tried doesn't work. I think the cargo lights now run through the BCM (maybe, remember, I'm not a EE).

I just removed the middle lights completely. Easy to do. The clips are on the short ends of the lights and harness disconnects from the main harness easily enough. Eventually I'll probably get frustrated enough to take the rear light out too. Not there yet. Did I mention sparky stuff scares me?

I am an IE so I even less understanding about electricity! After 4 reads of the BEMM and not finding a fuse for the cargo lights I found the table showing the BCM outputs.

I suppose all things electric are going this way. Less cost, more control and most importantly for Ford, beyond the reach of (most?) people for self repair. It looks like the modem that sends your data home to the mothership in Dearborn is now powered through the BCM. I guess too many people were pulling fuse #32 to disable it. My guess is if I can find it (under headlined?) and unplug it there will be other "unintended" consequences. My hope is that it doesn't communicate if I don't enable FordPass. Also hoping it won't be a parasitic draw. Unfortunately I think the horse has left the barn, never to be retrieved, in terms the consumers digital and repair rights.

 

[tngw1500se]

😂🤣😂

I've installed a house battery and in the middle of installing my own lights. I'll leave the factory lights in operation.... for the moment!

The other guy that has to go is the guy who engineered the cargo light wiring raceway clips. I've broken nearly all of them in the last few days. Stopped at my local dealer and they want $6.00 each for them!

Semper Fi,
Jeff

I was going to wait until I decided on a ceiling and just leave them alone until then but I couldn't stand it! Sometimes on. Sometimes off. They have a mind of their own. I ran new wires to all four of them and put in switches. Got power from CCP 1. I absolutely hated them!!! I put the back two on one switch and the front two on another. I wired an LED strip as the main source of light while camping. We call the factory LED's "Cleaning Lights" now.

If you can, don't try and pull all the clips out. Sometimes I was able to slide the plastic raceway to the side and out of the remaining clips. I broke two.

 

[GunnyR]

Hah! I'm a Retired Marine. Trust me, I can screw up a crowbar in a sandbox! Not much scares me other than plumbing and tile. Auto electric merely frustrates me.... a lot So my solution to improve my lighting was to simply add my own cargo lighting running off a house battery. Problem solved!

I found the P/N for the cargo light wiring harness raceway retaining clips: BU5Z13A506A.

 

[njvagabond]

I was going to wait until I decided on a ceiling and just leave them alone until then but I couldn't stand it! Sometimes on. Sometimes off. They have a mind of their own. I ran new wires to all four of them and put in switches. Got power from CCP 1. I absolutely hated them!!! I put the back two on one switch and the front two on another. I wired an LED strip as the main source of light while camping. We call the factory LED's "Cleaning Lights" now.

If you can, don't try and pull all the clips out. Sometimes I was able to slide the plastic raceway to the side and out of the remaining clips. I broke two.

I like that plan. Maybe because I can actually understand it.

 

[sirfallsalot]

Disclaimer: I'm an ME, not a EE. Sparky stuff scares me.

I have, however, read all 435 posts on cargo lights more than once. As near as I can figure out, it all got changed for 2020. So the helpful information about adding a switch onto a specific fuse no longer applies. Not a solution, but at least explains why the information you've tried doesn't work. I think the cargo lights now run through the BCM (maybe, remember, I'm not a EE).

I just removed the middle lights completely. Easy to do. The clips are on the short ends of the lights and harness disconnects from the main harness easily enough. Eventually I'll probably get frustrated enough to take the rear light out too. Not there yet. Did I mention sparky stuff scares me?

Aaaaahhhhhh!!!!! Does anyone have an actual wiring diagram of the interior lighting on a 2020 T250?

I've read a few threads about adding various switches and/or relays to change the way the silly cargo lights are controlled. In at least one of these threads it says that the lights are ground switched to turn them on/off, and that the 12V power is always on. Not true in my van. I measured power at the light itself, and the blue/white wire at the light is hot (12V). Black is ground. When I depress the pushbutton switch at back doors, the 12V blue/white wire at the light turns off (interestingly, the wires to the back door switch are blue/white on one side, black on the other. No idea what it's actually switching).

There is a 3-position switch at the cab light above the windshield. Here's how it behaves:

"O" position: The the cab/dome light is always off. Open/close the front doors and the cab and cargo lights both stay off. Open the cargo doors, or unlock the cargo doors with remote, and the cargo lights come on but the cab light stays off. Leave cargo doors open & light stays on for 30 minutes, then turns off until door is closed/opened (door switch activated), or unlock again with remote.

"I" position: both cab & cargo lights are always on, even after closing and locking all doors with remote. In this position they will go off in 30 minutes.

Middle position: all lights come on when passenger or cargo doors are opened. Leave the doors open and they turn off in 30 minutes. Close the doors & they go off in a few seconds.

Any time the cargo lights are on, you can turn them on/off with the switch at the back door. After they go off due to timer, switch at back has no effect.

So I have no idea how this thing is wired up.

What I want to do is have it work as it does above, but also be able to turn the lights always-off (no matter what), or always on (no matter what. Timer be damned. If I kill the battery it's my own fault).

After typing this, I think the smart solution is to use a DPDT 3 position switch:

• "O" position: always on (power and ground supplied directly from battery)
• "Middle" position: always off (power/ground disconnected)
• "I" position: stock config (power and ground supplied by existing wiring)

Then add a dimmer between switch and lights so that I can dim any time the lights are on.

Now I just need to figure out exactly where to cut the stock wires, and where to source the 12V (CCP I suppose).

Also, it would be nice to understand how the rear switch is wired. Will it still work after I install the DPDT? My kingdom for a wiring diagram!

OK then. Now that we know that everything changed for 2020, does ANYBODY know where the main wires are that feed power/ground to the 4 cargo lights on a 2020 T250? Each light has a white/blue wire and a black wire, but I can't find where they are all sourced from, and I really hate the idea of unwrapping the entire wire loom to figure it out.

 

[tngw1500se]

OK then. Now that we know that everything changed for 2020, does ANYBODY know where the main wires are that feed power/ground to the 4 cargo lights on a 2020 T250? Each light has a white/blue wire and a black wire, but I can't find where they are all sourced from, and I really hate the idea of unwrapping the entire wire loom to figure it out.

If yours is a cargo van, there is a plug behind the black plasitic wiring cover on the drivers side for the front pair. It goes to both front lights. I removed that harness. The lights come out "kind of" easy with a straight screwdriver pushing in on side to release the molded in clip. I just rewired all four into two sets (front and rear). The front one are controlled with three residentaial style switches. One in the step and one in the "kitchen", the third is back by the bed. I used two 3-way switches and a 4-way. I run them off the house battery. I may add a fourth 4-way up by the e-brake handle.

 

[sirfallsalot]

If yours is a cargo van, there is a plug behind the black plasitic wiring cover on the drivers side for the front pair. It goes to both front lights. I removed that harness. The lights come out "kind of" easy with a straight screwdriver pushing in on side to release the molded in clip. I just rewired all four into two sets (front and rear). The front one are controlled with three residentaial style switches. One in the step and one in the "kitchen", the third is back by the bed. I used two 3-way switches and a 4-way. I run them off the house battery. I may add a fourth 4-way up by the e-brake handle.

View attachment 148452

Oh, you mean the wiring cover that I broke most of the brackets off of when trying to remove it? Yes, cargo van, and I found that plug. I was hoping to find the single source of power to that and the back lights, so that I only have to add the DPDT in one spot. I'm not creating a true "camper" out of my van, so I don't really need 3 or 4 way config. It's my daily driver, so most of the time the van will be my "pickup/work truck". Then I'll also use it to haul my dirt bike, go to the hardware store, blah blah. So, I'm just configuring it so that I can camp in it with cot & sleeping bag. I bought a porta-potty, propane heater, added a roof vent/fan, and put a 750W inverter in. Once paneled and insulated it'll be good enough for camping a night or two when needed. Otherwise I have a 24' Class C RV for "real" camping (OK, glamping) ;-)

 

[me&z]

Yes. Plug for the middle lights are behind that pita to remove, hideously large wire race way. I only broke 2 of the clips. Mostly because Z took over and is more patient than I am.

I have NOT spent any time on this, but quick glance at the plug makes it appear that the wires are coming from the rear. Which kind of makes sense to me because of the shut off button on the D pillar. I'm thinking power goes all the way back there first and then comes forward.

When the weather improves, I might poke around that momentary switch. Might be some place back there to install a hard shutoff. When you need light, those are nice and bright. But when camping I just want them to stay off.

 

[tngw1500se]

Yes. Plug for the middle lights are behind that pita to remove, hideously large wire race way. I only broke 2 of the clips. Mostly because Z took over and is more patient than I am.

I have NOT spent any time on this, but quick glance at the plug makes it appear that the wires are coming from the rear. Which kind of makes sense to me because of the shut off button on the D pillar. I'm thinking power goes all the way back there first and then comes forward.

When the weather improves, I might poke around that momentary switch. Might be some place back there to install a hard shutoff. When you need light, those are nice and bright. But when camping I just want them to stay off.

I understand wanting them "off" but I also wanted them "on" while working on the van. The FN things would go off right in the middle of doing something. Made me go up and turn the key on and off to reset them. That's why I rewired the whole Ford light mess to the house battery.

 

[me&z]

Full on would be nice too. But only if, as you did, wired to a house battery which we don't have.

 

[tngw1500se]

Full on would be nice too. But only if, as you did, wired to a house battery which we don't have.

I can understand not wanting to have them stay on without a house battery, "Back in the day" older cars would allow us to leave the dome light on and run the battery down. Been there done that! I guess we were expected to be more responsible vehicle owners back then. If I were running them off the starting battery (without "time out"), I'd consider using two instead of four. I'd think two would light the van up nicely inside using half the power. For camping, I'd still add a LED strip light set. The factory LED's are such an X-Ray light and LED strips make you look so professional to fellow campers, especially in states that have legalized weed.

 

[me&z]

We just have a few Harbor Freight flashlights in the van. You know, the ones they give out for free. Between the magnet and the hook, we can position any where we need. We only use van for travel and sleeping so have no need for very much light. If it's dark, we're in bed

I did mask them off and have Z spray paint them because the original color clashed with our window shades.

 

[njvagabond]

We just have a few Harbor Freight flashlights in the van. You know, the ones they give out for free. Between the magnet and the hook, we can position any where we need. We only use van for travel and sleeping so have no need for very much light. If it's dark, we're in bed

I did mask them off and have Z spray paint them because the original color clashed with our window shades.

My wife just hung one of those from our IKEA chandelier with stylish but insufficient flame bulbs that hangs over the dining table which has now become the pandemic jigsaw table. Engineers! I refuse to paint it to match.

 

[BobATX]

So is the original poster correct and if I find the white with blue stripe wire with 12 v at the switch in the back I can cut that wire and place an On(oem)/Off switch in?? I don't care about always on.

 

[sirfallsalot]

So is the original poster correct and if I find the white with blue stripe wire with 12 v at the switch in the back I can cut that wire and place an On(oem)/Off switch in?? I don't care about always on.

No, I don't believe so. The switch at the back doesn't have 12V. It's a momentary switch that grounds the white/blue wire when pushed, and lets it float (at somewhere around 3V) when not pushed. This is an input to the BCM, which looks for a transition of that signal (from 3V to GND and back to 3V) as a command from you to turn the other white/blue wire on (12V) or off (0V). You need to find the white/blue wire that is the 12V output of the BCM, and put an on/off switch on that. The easiest place to find it is right behind the driver seat, where there are only 2 choices of blue/white wire in the harness. Strip a small amount of insulation from one of the two, and measure the voltage with the lights on. If 12V, that's the one to cut & switch (always-off or on-via-BCM). If it's 3V or GND, check to other white/blue wire.

 

[Transit Trader]

Aaaaahhhhhh!!!!! Does anyone have an actual wiring diagram of the interior lighting on a 2020 T250?

I've read a few threads about adding various switches and/or relays to change the way the silly cargo lights are controlled. In at least one of these threads it says that the lights are ground switched to turn them on/off, and that the 12V power is always on. Not true in my van. I measured power at the light itself, and the blue/white wire at the light is hot (12V). Black is ground. When I depress the pushbutton switch at back doors, the 12V blue/white wire at the light turns off (interestingly, the wires to the back door switch are blue/white on one side, black on the other. No idea what it's actually switching).

There is a 3-position switch at the cab light above the windshield. Here's how it behaves:

"O" position: The the cab/dome light is always off. Open/close the front doors and the cab and cargo lights both stay off. Open the cargo doors, or unlock the cargo doors with remote, and the cargo lights come on but the cab light stays off. Leave cargo doors open & light stays on for 30 minutes, then turns off until door is closed/opened (door switch activated), or unlock again with remote.

"I" position: both cab & cargo lights are always on, even after closing and locking all doors with remote. In this position they will go off in 30 minutes.

Middle position: all lights come on when passenger or cargo doors are opened. Leave the doors open and they turn off in 30 minutes. Close the doors & they go off in a few seconds.

Any time the cargo lights are on, you can turn them on/off with the switch at the back door. After they go off due to timer, switch at back has no effect.

So I have no idea how this thing is wired up.

What I want to do is have it work as it does above, but also be able to turn the lights always-off (no matter what), or always on (no matter what. Timer be damned. If I kill the battery it's my own fault).

After typing this, I think the smart solution is to use a DPDT 3 position switch:

• "O" position: always on (power and ground supplied directly from battery)
• "Middle" position: always off (power/ground disconnected)
• "I" position: stock config (power and ground supplied by existing wiring)

Then add a dimmer between switch and lights so that I can dim any time the lights are on.

Now I just need to figure out exactly where to cut the stock wires, and where to source the 12V (CCP I suppose).

Also, it would be nice to understand how the rear switch is wired. Will it still work after I install the DPDT? My kingdom for a wiring diagram!

UPDATE: I found a wiring diagram. See attached. For the 2020 T250 (148" med roof), there are 2 wires in the wiring harness running from behind driver to back of the van, that are white with blue stripe. Apparently both wires connect to the BCM. When the lights are on, one of the wires has 12V and the other appears to be floating at about 3V. If I toggle the switch the floating line is grounded. So, I believe that the 12V output is feeding power to all of the cargo lights under BCM control, and the other is just signaling to the BCM that you want to turn the lights off. I cut the wire with 12V, and cargo lights went off as expected. Now, I will install a SPDT on-off-on switch (3 connectors). To the left connector I will connect the 12V output from the BCM. To the middle connector I'll connect the power to the lights. To the third connector I'll wire 12V from the battery (fuse block connected to the CCP). Thus, the switch will allow "always on", "always off", and "BCM driven".
View attachment 149065 View attachment 149066

I had a hard time understanding Hein's wiring diagram as I am not real electrically inclined, so I had my friend "Filter Guy" on the DIY Solar forum draw a diagram for me and walk me through making it real. I now have Hein's good switch in my dash and the dimmer on the wall and everything works perfectly on both the van's batteries and my LifePo4 house batteries: