How to fix the mouse belt

These are the steps I used to replace the passenger side ribbon on my '90 Testarossa.

Background: A friend got out of the car too quick and bumped into the mouse while it was still moving. It stopped working and the seatbelt light came on.

I will break this into two sections within this thread. The first section is the trim removal. The second will be the ribbon spool replacement.

Here's how I removed the trim. Start by removing the front screws on each of the sun visor brackets. Don't remove the rear screws.
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Carefully pull down the outer edge of the sun visor panel while pulling the inner edge out from under the overhead console.
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Removed!
This is the panel's backside and shows why you don't want to touch the rearmost screws for the sun visor.
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Reference for reassembly: this is where the inboard screw goes into
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Outboard screw goes here. You can use an eyeglass screwdriver to align the hole when reinstalling
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Lift the leather tab to reveal the only screw for the pillar trim panel
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This is the hole for reinstallation
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Now you are ready to carefully pry the pillar panel off. Here is the backside for reference. The panel clips install on this panel in the two slots.
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Close up of where the rearmost clip lives:
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Forward clip lives here:
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Next post will show the where the clips are pushed into.

 

Here's where the clips are pushed into:
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You will damage the clips so don't worry about them. They are inexpensive and easy to replace.
The Ferrari P/N is 40048100. What a pain to find them and once I found the part I couldn't get this from my parts source. I ended up going to O'Reilly's and getting these:
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Black is the Ferrari part. The GM clip is superior. It is inexpensive, easy to source, locks into the aluminum panel and will not rotate out. It is slightly wider and a little more pliable than the Ferrari part too. I couldn't reseat the Ferrari part no matter how I tried to align it. The GM part is slightly longer so it was way easier to line up and gently press in.

Now that you know what the clips look like (and live) it is time to pry. Buy an interior trim panel removal tool and do the rearmost clip first. Be gentle, the Ferrari clips have no collar to pry from. You'll carefully pry between the aluminum trim panel and the steel mounts on the body.

Success! Don't try to remove the panel yet --still have some tabs to clear. The first is here at the rear of the pillar trim panel (at the lowest part). There is a tab that slots into the red circle below. Just lift the rear of the panel up about an 1" and pull the rear of the panel inboard to clear the door trim piece.
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These are the tabs at the front of the pillar:
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Hold onto the pillar trim panel and slide along the pillar to remove. You only need to slide it 2" to clear these tabs.
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The pillar panel is finally off. The next panel is a piece of cake. And here is the backside for reference:
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Just three screwed down tabs. What is barely pictured is the top, long trim piece, that runs along the quarter glass. This is attached to this trim panel and stays attached.

First you carefully pull forward the seal expose the leather wrapping around the flange.
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Then unfold the leather from around the flange.
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This piece pulls car forward to expose the other two tabs to unscrew.
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Unscrew all three tabs and pull the forward edge of the trim panel inward, removing the panel.

This wraps up the trim panel removal and its reassembly. Next post will be replacing the ribbon itself. I'll get to this soon.

 

Here is the next section on how I replaced the ribbon. To remove the motor assembly switch off the battery, disconnect the white connector and remove the two nuts/two bolts circled below:
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My B Station switch was broken making it easier to do the repair in the car (more on this later). If yours is intact, mark the locations of the nuts holding the rail to the body, then remove them. They run the perimeter of the rail.
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In order to get the ribbon out you need to separate the B Station switch from the B Station. Mine was done for me by the broken ribbon. Below you can see the broken plastic portion of the switch inside the metal rail:
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I then started to remove the remnants of the B Station switch to rapid prototype a stronger piece by removing this clip:
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Compress the clip ends and push rearward: Image Unavailable, Please Login


With the clip removed there was no give. I noticed a set screw in the rear of the assembly:
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I didn't want to further damage the plastic pieces inside the B Station. Since the switch still worked it just needed to be held up into place. After thinking about the effort vs. reward of removing the pieces to print a replacement... keeping it simple wins. I will make a bracket to support my B Station switch. The switch works fine it just lost its mounting tabs.

To continue you need to disengage the "mouse" from the ribbon. Use the red button to unclip the seatbelt then use the black button to move the "mouse" away from the clip on the ribbon end.

Then pull the motor assembly off the studs and down. Be careful because there are small parts that you need to keep track of. Slowly pull the ribbon out until you see this:
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These plastic pucks will be covered in white grease and are easy to lose. I only had three. Be very careful with these. A complete assembly looks like this:
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Take these pucks off for safe keeping. The motor assembly can be moved further away from the rail now. Next remove the three bolts holding the motor to the mounting bracket. This gives you access to the spool cover which comes off with three tabs:
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Speaking of differences my pictures show slightly different parts. I will point them out as I go. My car has the upgraded parts from the recall service. The donor parts are from an original car.

When you remove the spool cover you'll see the white spool held on with one nut over one of these retainers. Old style is above. The recall performed cars come with the unit below. Remove the nut and retainer.
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Then you can remove the spool with reverse pliers. Mine was jammed due to the broken ribbon. I ended up buying a motor assembly from an Alfa Spider to see how to take it apart.
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Slowly lift up the spool and you'll see how it works. The ribbon goes through the guide and is fed into the spool. The ribbon is held into place with two different sized notches. You can't install the ribbon backwards since the notches index to the spool. Image Unavailable, Please Login

The guide has a pin which slots into the spiral groove of the spool. This feeds the ribbon.
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This picture shows the guide. The original is nylon. The updated part is cast metal. There is no need to remove this so I didn't snap a picture of the updated part. Same shape, just different material.
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Next unwind the ribbon and remove the spool. Then you can slide the ribbon out of the B Station switch. The ribbon is far more flexible with the update. The original part is noticeably stiffer. The ribbon clip that goes into the mouse is also different. The newer version (on the right) has a different profile and different spacing for the white pucks.
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My replacement ribbon (thanks Tim!) was an original part so the clip was different. After noting the orientation I pressed out the pin holding the original clip and replaced it with my later part. The next thing I needed to replace was the missing puck.

I had no luck getting a salvaged part. I wanted to get back to driving so I made a replacement. I grabbed a similar nylon to cut out my puck. I drilled the 1/16" hole first, then used a hot blade to cut it out. I filed and sanded it down, getting it close to the originals. Here is the part I made (right most puck).
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Now I was ready to install the ribbon. Make sure the direction is right before feeding it in. The ribbon only goes on one way. I added a light coat of silicone grease to the ribbon and to the back side of the spool. I fed the ribbon through the B Station switch assembly, though the guide and pulled enough through to feed the ribbon end into its notches on the spool. Feed it around a few grooves to make sure it is somewhat locked into place. Then pull the excess ribbon out through the B Station switch while slowly placing the spool onto the motor's drive. Make sure to not force the guide's pin into the groove. Wiggling the spool helps it to sit correctly. Once the spool is seated you can lightly install the retainer and nut to hold it in place. Don't tighten since you want to be able to manually spool it.

This is where this writeup is going to get confusing. I did this repair without removing the A Pillar trim from the car. I just had it popped off its two interior clips. I didn't know how to fully remove it and have a fear of interior clips. I dread dealing with them. Especially ones I couldn't source and mounted on thin aluminum panels. But a member, that I hold in high regard, asked me to detail the process on how to remove the interior panels --so I ended up facing that fear. It was only after I got the belt working that I took the A Pillar trim off.

You can repair the ribbon with the rail still installed but I wouldn't recommend it. Just take the interior panels off. It really isn't a bad job. I wish I would have stepped up to my fear sooner. This job is best done on a bench. Either way the next step is feeding the ribbon into the rail.

I put some more silicone grease and installed the pucks. The one I made blends in with the rest.
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Then carefully feed this clip into the rail. They go into the rearmost slot.
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Feeding it in.
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I ended up running the ribbon all the way out to the A Station (by the side mirrors). I thought the sequence of winding the spool was critical since the car either starts with the belt at the A switch or B Station. I realized, after the fact, it doesn't matter and the car "resets" the position of the ribbon itself. I tightened the nut on the spool, installed the cap. I then mounted the motor assembly back into its bracket and then back into the car.

 

Going back to differences. The motors are the most noticeable change. They are much larger with the updated parts:
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Motor brushes are far larger with updated electronics:
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Since I was convinced the "mouse" needs to start at the A switch I removed the case of the motor to manually wind the ribbon. Here are some detailed shots of the motor:
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I used the motor shaft to adjust the position of the ribbon and reinstalled the motor case. I then connected the harness but needed to address the broken B Station switch. I ended up making a bracket to support the B Station switch.

I took 26 gauge sheet metal and bent up a bracket that holds the switch up into the B Station. The B Station switch is pure design obsolescence.

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So with that switch addressed. I clipped the "mouse" into the ribbon and was ready for a test run. I turned on the battery switch and heard the seat belt tensioner run. I opened the door and the "mouse" barely moved. I triggered the switches and nothing happened. Closing the door did nothing. I then disconnected the battery again (30 seconds) and tried again. It moved halfway then stopped. I was pretty convinced the repair failed. But the slight glimmer of hope was it was getting slightly better. So I disconnected the battery and repeated this sequence 10-15 times. The belt finally started going through its full motion . It is because of this that it doesn't matter where you start the belt. You don't need to have it start at a specific point. It will eventually correct itself.

After this I lubed up the rail where I noticed it was hanging up with silicone grease. I installed the interior panel and it has run many more cycles since. I now watch passengers when they open the door and make sure they wait until the mouse belt stops moving. Lesson learned.

I couldn't have done this without 302Tim. I couldn't find this ribbon and you bailed me out. Thank you so much for your generosity. My car works because of you.

 

I looked into doing a conversion; it is straight forward. Fortunately the mount is already on the B pillar. The time consuming part is sourcing all the trim (I was able to find most of it).

But ultimately I wanted to keep the car as is. The car is nostalgia and these belts will never come back. It looks cool to see them pulled forward. And it is so cheesy to see them run. I love it.

 

You're welcome. I am happy this helped.