Sun Roof Problem

[fjstl]

I completed a search and found nothing on this topic.

I have a 98 ls 400 with 80k. When I press the button to open the sun roof, it remain open. When I press the button to close it, it closes but then immediately reopens when it reaches the closed point. Noe, in order to close it, I have to keep tapping the button and it will eventually reach the close state and remain there.

Has anyone experienced this problem?

[SKperformance]

You have a problem with the motor and its sensors.

Either a wire is broken in the roof or the motor needs replacing.

[Threadcutter]

I completed a search and found nothing on this topic.

I have a 98 ls 400 with 80k. When I press the button to open the sun roof, it remain open. When I press the button to close it, it closes but then immediately reopens when it reaches the closed point. Noe, in order to close it, I have to keep tapping the button and it will eventually reach the close state and remain there.

Has anyone experienced this problem?

fj:

With all due respect to everyone, I believe your motor (all by itself) is probably working fine, given that it does open and close the sunroof. I've never seen any electrical schematics for the sunroof system, but I would tend to think that there are sensors/switches that open up to "signify" an "end of travel" condition. In other words, even if you continue to press the button/switch for a particular direction after the sunroof has reached it's mechanical limit(s), the internal limit switch will open up and not allow the flow of current to the motor any longer for that direction of travel. This automatically overrides manual control and prevents the motor from being overloaded/overcurrented/burned out because it's at the end of it's mechanical travel.

For the time being, I would leave it (the sunroof) closed and do some research on what the electrical control system actually "looks like" from a schematic persective. After you've done that, you'll probably have to pull the headliner to gain access to the limit switches. My guess is that there's a front/closed limit switch that isn't working properly. Don't be surprised if the switch/sensor is actually located in the back area of the sunroof opening. It might even be that the reason is that the drains are clogged & (rain)water has gotten into the limit switch and damaged it. I do concurr with SK that it probably is either sensor(s) or loose/broken wire(s). I wouldn't take the headliner off & go on an "easter egg hunt" until I had reviewed the schematics.

TIZ

I think if you're a little patient & do your homework, this will probably actually be a cheap, easy fix.

[fjstl]

I completed a search and found nothing on this topic.

I have a 98 ls 400 with 80k. When I press the button to open the sun roof, it remain open. When I press the button to close it, it closes but then immediately reopens when it reaches the closed point. Noe, in order to close it, I have to keep tapping the button and it will eventually reach the close state and remain there.

Has anyone experienced this problem?

fj:

With all due respect to everyone, I believe your motor (all by itself) is probably working fine, given that it does open and close the sunroof. I've never seen any electrical schematics for the sunroof system, but I would tend to think that there are sensors/switches that open up to "signify" an "end of travel" condition. In other words, even if you continue to press the button/switch for a particular direction after the sunroof has reached it's mechanical limit(s), the internal limit switch will open up and not allow the flow of current to the motor any longer for that direction of travel. This automatically overrides manual control and prevents the motor from being overloaded/overcurrented/burned out because it's at the end of it's mechanical travel.

For the time being, I would leave it (the sunroof) closed and do some research on what the electrical control system actually "looks like" from a schematic persective. After you've done that, you'll probably have to pull the headliner to gain access to the limit switches. My guess is that there's a front/closed limit switch that isn't working properly. Don't be surprised if the switch/sensor is actually located in the back area of the sunroof opening. It might even be that the reason is that the drains are clogged & (rain)water has gotten into the limit switch and damaged it. I do concurr with SK that it probably is either sensor(s) or loose/broken wire(s). I wouldn't take the headliner off & go on an "easter egg hunt" until I had reviewed the schematics.

TIZ

I think if you're a little patient & do your homework, this will probably actually be a cheap, easy fix.

[SKperformance]

The sensor is located on the cam of the motor , that is how it know when to stop by revolutions.

[1990LS400]

The 1998 model year LS400 sunroof has a feature called "pinch protection" which is supposed to reverse the sunroof if an obstacle is detected. I don't know how this feature works and I am surprised that the eleven pages about the sunroof in my 2-volume 2000 LS400 repair manual set does not mention it.

I wonder if something (e.g. the wind deflector) is binding or if the sunroof is out of adjustment.

Was the sunroof working properly and did this problem just start happening? Has the sunroof glass been recently replaced?

I suggest inspecting the wind deflector to make sure it is retracting properly and that the arms on each side are not bent. Also cleaning all the sunroof mechanism (e.g. the rails) you can see might be good start -- I happened to do this just last week on our 2000 LS400. Perhaps have someone close the sunroof while you watch from the outside while you watch to see if anything is causing binding or excess friction.

[Threadcutter]

The sensor is located on the cam of the motor , that is how it know when to stop by revolutions.

S:

Makes perfect sense, Thank You for the clarification. The pinch protection in all likeliehood monitors the motor current and "end of travel" sensor. If there is an "overcurrent" condition AND the end of travel sensor hasn't "tripped" yet, then it is assumed that there is a "jam" (like finger(s) or hand(s)) in the openeing.

If a person were to install a replacement motor, then what is the procedure for aligning the motor/cam so that the panel is fully closed when the cam/sensor shuts off the motor? My guess is that there is a setscrew that one loosens to manually rotate the cam on the mainshaft until everything is properly aligned.

It could also be that the rails & ballscrews just need a good lubricating. This could cause the "system" to think there is a "pinch" condition, when it's really just a lack of lubrication. Coincidentally, I did mine about 3 weeks ago with aerosol (using a "straw/tube") white lithium grease. It goes on in liquid form, the solvent flashes off, leaving white lithium grease. Works well, but have some paper towels handy.

[fjstl]

Threadcutter, what is the name of the product you used?