This is actually my second XC90, as I leased an '04 a LONG time ago, but I did no work on it so I didn't really KNOW the truck. I plan to do anything needed that I can handle.

Most everything works, save a few typical issues: Alarm service required and anti-skid warning messages, and two error codes for either the evaporative emissions purge valve or the pump. I've read a bit about all of them but first up is the sunroof.

I care somewhat about the sunroof working, not so much about the alarm, at least not enough to pay for a new one and go to the trouble of replacing it. I read a thread that suggested that if you pull fuse 26 under the steering wheel, the alarm system would not try to work and the sunroof might get power once again. I tried that. The fuse wasn't blown, but it didn't fix anything: I still get the error message and I still have no functional sunroof. I also checked the sunroof motor fuse at the driver's door end of the dash, and the fuse is good. Interestingly, the red blinking light on the dash when you lock the vehicle still works. I would have though that was part of the alarm system and with the fuse out, would not work, but it still does.

Like I said, I would be pretty happy if I got the sunroof to work, and if I could do that without buying a new alarm module, perfect. Any thoughts on why pulling the fuse works for some but not all? Surely there must be some way to bypass the alarm's interaction with the sunroof.

Are there any online manuals or schematics? I've seen some links, but they've all ended up being dead.

Thanks in advance...

Here's a quick picture of my new daily:

 

Actually I just read that fuse 26 is the siren, not the alarm system, so that explains why the red LED still blinks when the alarm is armed.

I also read in the same spot that fuse 28 is the sunroof. The little panel with the diagram on the driver's end of the dash said the sunroof fuse was in there, I'm sure of it. That's the one I checked, but maybe I need to check fuse 28. I'll check that out tomorrow...

 

Somtimes when the siren module goes bad it prevents the sunroof from working - I have fixed that by replacing the siren module on a couple of cars. I have heard that if you simply disconnect the siren module that can restore sunroof function, but never tried that solution.

 

I wonder if I can disconnect it without drilling out the fender liner rivets, etc.

 

Well, internet info on fuse location is just all over the place. I mentioned the sire fuse at #26 under the steering wheel, and reading somewhere that #28 was actually the sunroof fuse. Now I find a site with diagrams for all the fuse boxes, but it says that the siren fuse is actually #8, and there is nothing at #26 (mine definitely had a fuse at #26) while #28 is a power passenger seat fuse. They also say that the sunroof fuse is #15 in the fuse panel on the end of the dash, which is what my car seems to have (or at least the sticker says so). What gives? Did fuse locations jump around that much over the 1st gen years?

 

Yes the fuse for the siren module is in position 8 - on the CEM. Note the BUS wire (with the square wave drawn above it) goes from the siren to the sunroof module to the upper electronic module - If a bad signal occurs in the siren module on the bus wires - it can create problems with the sunroof or remote lock/unlock. The UEM is mounted to the back of the inside rear view mirror. If you have a bus wire in the Siren module that has a short to ground - taking the power away/removing the fuse will not change that. What happens is the backup batteries in the Siren module corrode and leak onto the circuit board causing those problems.

 

Actually that does make sense now, thank you. Looks like I need to yank that module, even if I don't spring for a new one.

 

Has anyone had any luck bypassing this module? Only 3 wires... 2 are power probably? 3rd is trip maybe? Can we trick the car into thinking the module is there as to not leave a warning on the dash?