04 D2, my rear sunroof randomly opens slightly when I turn the car on, it happens at least 50% of time. The weirdest thing, some times I can hear it and close it and sometimes opens like a freaking ninja and close it when rain pours in

anyone has experienced similar issue? Any suggestion on how to diagnose/fix?

Thanks 🙏

 

Sunroof ECU, or the button is sticking. Could be water damage from a leaking sunroof.

 

thanks, any suggestion on how to fix it?

 

Do you have water stains on the headliner? That would suggest possible water trouble. One thing to always do with our trucks is to ensure good battery and charging systems. Electronics (all of our xCUs) MUST have sufficient power provided to them, They WILL behave unpredictably without that. One thing to check is your battery voltage before starting to see if you have any correlation between the 50% of the time that Regan shows up and a lower voltage. Another thing to always do is to disconnect and reconnect all of the connectors in the path of control of whatever device is misbehaving. In this case, your rear sunroof control switches, your rear sunroof lockout switch, and the sunroof ECU. I think the only way to get to the ECU is to pull the headliner (someone correct me if I'm wrong here). Do what you can get to easy first. Maybe your ECU is bad. The BCU controls the SR ECU, but I'm guessing that is just an enable/disable signal so probably nothing, but you can see if manual control of that signal changes anything. If you don't understand electrical systems, now would be a good time to commit to learning some of that. You can't own these without coming face to face with electrical problems.

 

@H20nSnow thanks for the detailed response. The headliner staining is a good question, I do see a few “wave” stains in the headliner but I always thought they were from instances when either PO or myself let a bit of rain in before realizing the SR opened. I have monitored the SR in close position when raining and can’t really see any wet spot in the HL, but this is in me assuming that a leaky SR will produce such spots, let me know if there is a better way to confirm leakage.

On the electrical prowess, I must confess I’m an ignorant, as you mentioned, I do need to spend some time learning. If you have any helpful resource or reference to share that would be great.

 

Some folks solve this problem with a caulking gun, and pulling the fuse.

 

I just went through the exact thing on my 04. Rear sunroof would open just about an inch when the ignition was turned on. It would do this about 20% of the time, and i couldn't find any pattern as to when it would happen; and just got in the habit of reaching up and hitting the close button every time i parked. When i did the headliner, I resealed the sunroof's, redid the drains, and taken both motors and cleaned those up. At that time, I had also taken the little sunroof ECU out and looked at the board. It was spotless. No corrosion, cold solder joints or anything that looked fried. I guess it doesn't matter how electronics visually look. if you can't check it out with a meter and know what each thing should read, you're just guessing that it works. I bought a used sunroof ECM off ebay for like $40.00 and put it in. Works like a champ now-not one single unattended opening. Very easy to put in as well, no headliner removal needed. Just remove the overhead map pocket tray above the visors and the ECU is held in with two screws, and is located in the area behind the switches.

 

@1dummy this is super helpful man, appreciated