97 Mark VIII... sunroof inop

My moonroof fuse was blown.  Replaced fuse.  When I hit the button I get a few, rapid, relay-type clicks coming from the roof, then it blows the fuse again.  Along with the clicks I get flickering interior lights.  Obviously overamping.  Something is wrong... stuck moonroof, bad motor, crusty wiring?  Who knows.

Anyone have alldata or similar that could give me a few pointers before I rip out a headliner needlessly?

There should be an access panel in the headliner above the rear seat for the sunroof motor. I'd try looking at the motor while someone else runs the switch to see what happens.

In reply to Will :

I'll give it a shot.  It blows fuses fast, so I'm not sure it will tell me much.  At least now I know where it is and I can get a multi-meter and check some things.

My guess is that the sunroof is stuck and the motor is skipping. I  would be extremely cautious as you could be stripping the motor gear or sunroof tray gear. 

Can you remove the motor and try to manually operate it? Or try to remove the sunroof panel and inspect the cables? 

It is definitely not skipping.  I get about 3 electrical clicks in the span of a quarter of a second and the fuse is blown. 

Process so far.

1. replace fuse, try, fuse blows after 1/4 second and a few ticks
2. pull motor off track letting it dangle from the roof and watch the gear when I hit the button.  No motion, just the same clicks and another blown fuse.
3. unplugged motor and tested it on the bench... works great.

So I'm guessing it's not a stuck track (and there is no way to test that theory without a complete disassembly.)  Since the motor didn't move when I tested it in the car, my guess is that something upstream is shorted, which would explain why the motor tests OK on the bench, but not plugged into the car dangling from the ceiling.

My next step is to leave the motor unplugged and try the switch again.  If the fuse blows, I know I likely have a short between the switch and the motor.  If it doesn't blow, I'm totally stumped.  Problem is... I'm out of fuses and stuck at work until at least 8

Any chance that had a manual override with a crank somewhere? If so, see if you can crank it open/closed or is it bound up? Step by step removal link if it helps

Find a car with a similar shape of roof.  Cut out a repair panel a bit bigger than the stupid hole in your cars roof.  Weld it in place.

Win.

I just had the sunroof and headliner out of my 740 Volvo.  I'd forgotten how fragile and stupid they are, but it worked well enough to get it closed, so that's good enough for me.

In reply to Steve_Jones :

That link does help, but I'm not sure I need/want to replace the whole thing.  Something is causing the fuse to blow instantly, so I don't think it's a mechanical issue, especially since it blows the fuse even with the motor removed from the track.

I haven't found any override possibility.  The only thing I could think to do is chuck up the drive gear in a drill and shove it in the hole, but I don't think it's designed to be removed from the gear box.  Perhaps a junkyard gear box might donate it's gear.

I think it's time to at least partially pull down the headliner.  There was a mouse nest in the trunk so it's entirely possible that the little douchpickles got up there and chewed something.

Does it blow with the motor sitting on the bench? I'd agree it's electrical, could even be the switch itself. 

Check continuity between the switch end of the wires and the motor end, with both disconnected. Also, check continuity between the two wires at one of the ends. I hope what I typed makes sense.

I made a small drawing on my phone. 

Assuming there are only two wires. Check continuity between A - C, B -D and then also A - D. 

Steve_Jones said:

Does it blow with the motor sitting on the bench? I'd agree it's electrical, could even be the switch itself. 

Don't know yet.  Ran out of fuses and I'm stuck at work for a while.

Slippery said:

Check continuity between the switch end of the wires and the motor end, with both disconnected. Also, check continuity between the two wires at one of the ends. I hope what I typed makes sense.

It makes sense.  Problem is, there are 9 wires to cover all the power, ground, and limit switches.  I'm trying to find a wiring diagram so I can see what I'm testing.  There is also a moonroof module with two plugs on it that I can't figure out what it does.

This is for a 98, so I can't promise it's 100% accurate for a 97. But here are the relevant pages from the factory EVTM.

THANK YOU!