5th Bow Latching Motor

[flyhop]

CAUTION: Direct access of the motor really is a "last resort" kind of approach to fixing a convertible top. If the control module (computer) figures out that something is out of synch, it will disable the entire convertible operation. This includes the remote trunk button and the button that lowers all 4 windows at once.

This post is meant as a "how I fixed a problem as a DIYer and saved myself some time and money". My computer had already shut down my convertible, so messing with the latching motor wasn't going to do anything detrimental to the soft top.

Given that this is a simple on-off type motor, I won't promise that directly accessing it will shut down the soft top operation, but it's a good bet. To be really safe, I would remove the car's battery first so the control module is really OFF and may not register that something has been changed in the system.

Lastly, please bear in mind that the soft top operation is a complex dance of motors and microswitches, all of which are very precisely controlled by the control module or computer. If the control module notices a deviation or senses a problem, it will probably stop your soft top from moving.

So, be careful.

Work shown below if for a 1996 Saab 900SE 2.0L Turbo convertible

As has been described before, this convertible top is completely inoperable, meaning that pushing the "Roof" switch generates no movement, no motor sound, no nothing. The control module detected that the tonneau motor was removed sometime ago and has shut off all convertible top access.

The roof is closed, and the 5th bow is "locked" in place atop the tonneau cover. The issue at hand is that I need to remove the outer soft top for some restitching and readhere the rear window to the top. But with the 5th bow locked down, there's no way to remove the soft top. What I need is for the motor to unlatch the 5th bow and that's what this addresses.

And before anyone else posts, the emergency manual convertible top release only allows you to raise the roof. It does NOT release the 5th bow latch.

















From the WIS with help from John:
A DC motor opens and closes the latches that lock the fifth bow to the soft top cover. It is located under the cover and is connected to both fifth bow latches via control rods. The latch motor also operates the rotating covers at the front of the cover via torsion wires from the latches. The motor can be run in both directions by reversing the polarity of the motor connections. It is supplied with 12V from the control module when the locks are being operated, from pin 12 (K20) for locking and from pin 2 (K20) when unlocking. If the motor becomes blocked there is a current limiter switch in the control module.A microswitch in the left hand fifth bow latch detects whether the fifth bow is locked or not.
(Power from the TSAS control module goes to connector H10-15 which is a 10 pin connector above left hand wheel housing. Power from pin 2 (unlocking) goes to (8) on the ten pin connector and then to 1 on another connector to the motor).
The WIS statement above regarding reversing polarity means that 12v power can be supplied to pin 8 and grounding to pin 9 and will allow the motor to unlatch the 5th bow. 12v power to pin 9 and grounding to pin 8 allows the motor to latch the 5th bow. In my case, 12v power came from the luggage compartment's light.
NOTE: I changed the #4 fuse (interior lights/power antennae) from 7.5A to 10A just for this exercise. The latching motor pulls a good bit of power and blew the 7.5A fuse on the first try.

[Darren900]

Nice post! I especially like the "Fat Finger" label

[Vespa]

flyhop, you are a MacGyver of Saab 900NG convertibles. I'm working on a 5th bow locking assembly this week and I may be using your info to play with the motor while I figure out how the locking mechanism on the right side goes together.

Thanks for your pictures and hard work!

[Synapse]

Hey Thanks man !!! I had the same problem, and your solution worked like a charm. Soon as I touched the hot wire to it, FIXED! Joined the site just to thank you!

[Vespa]

Originally Posted by Synapse

Hey Thanks man !!! I had the same problem, and your solution worked like a charm. Soon as I touched the hot wire to it, FIXED! Joined the site just to thank you!

Synapse, did you find a loose power wire to the locking motor under the tonneau cover or perhaps a connector problem?

[Synapse]

Just the other night my top was somehow didnt lock down all the way and only gave me a soft top error. Motor would not budge (acted broke). About a 1/2 inch gap from the top and the plastic part it locks down too. The part around the back seat wasnt flush either, you could see gears. The rear glass was dipping. But it was locked somehow.

The Flyhop method allowed the top to unlock in the back and reset its self. It raises and lowers fine now.

[saabchilten]

this is borerline hijacking here, but didn't you tell me that you found your tonneau flaps in your trunk, vespa? means some part of your motor broke before the previous owner removed the strikers and disconnected it. whether jammed or connectors, i don't know. you'll have to test it yourself.






flyhop, i demand pictures when you get the canvas replaced! hope the eventual reprogramming goes well, and i want to see what my top will look like when the day comes i have to replace my canvas.

[john bernard]

flyhop ... those jumpers that you used to jump power? are they the leads from your multimeter?

[flyhop]

John,

Yes, those are my multimeter leads. Just used what was close at hand.

[Vespa]

I'm cautiously optimistic at this hour. I thought I'd let you all know of my progress in hopes that my solution will save time and money for you.

Similar to what flyhop has shown, I robbed power from the battery but did it in a more external way. I have some 20' jumper cables and ran them from my battery back to the tonneau area. I have the tonneau flipped up and 5th bow back (the first couple phases of putting the top down).

I went to Radio Shack and got an in-line automotive style (1 1/4" x 1/4") round fuse holder and a pack of 4 slow-blow 8 Amp fuses (they didn't have 10 Amp). I put the fuseholder w/ fuse in-line with one spade on the motor side connector and connected that to an alligator clip. A plain alligator clip to the other side. I started out not knowing what side would cause the motor to rotate out. I didn't pay attention so flog me for that but I don't think that's an issue in testing.

I clipped one alligator clip to one side of the jumper cable clamp and took the wire from the fuse holder and briefly tapped it to the other clamp. Big sparks but no movement. As I tapped the wire to the clamp I could hear the motor click faintly but no physical movement of the exposed center gear or the ratchet arms. I reversed direction, same result.

Now I unbolted the gearbox/motor assembly from the tonneau (10mm wrench I think, 4 bolts) and took the assembly over to my bench. I took the two long screws out (about 6mm but I used an SAE socket that was similar since 6 seemed too small and 7 too large). The motor came off and I started pulling it apart. Before I did I noticed that the motor and the gearbox moved freely when not engaged together.

The motor is not a complex thing but be very careful about the two thin springs that can pop out. The two springs push the brushes against the armature. I noticed that the armature (where the brushes contact) looked very dirty. I took about six or seven q-tips w/ denatured alcohol and cleaned it up until the black was mostly gone and the surface shiny copper.

I re-assembled the motor, re-attached it to the gearbox and had a go at it w/ the jumper/alligator cables and fuse. First try, no movement (RRR!). Flipped around polarity..."bzzzzt" out the arms went! Flipped polarity again, "bzzzzt" smooth as silk.

Maybe I'm lucky in that disassembling the motor and gearbox did something but I think it was the motor being an issue.

I will be putting things back together tonight and will test it. Only thing keeping things from being complete is that the pin I got at Ace to replace the missing one on the right latch/rod is a metal clevis pin I cut down. The original was made of plastic and I'm sure it was to shear off if binding to keep things from grinding to a pulp. Will have to replace that in the near future.

I'll keep you all posted but had to put this in while it was fresh in my head.

I have pics of some of this but my old 2MP Kodak is crap for close up focusing. I'll try and get them uploaded here when I'm all done.

[Vespa]

Good news first: It works! The latches move fine now. Only problem is that the function is reversed. I'm not sure what happened.

Did I put the motor case on backwards? If the magnets were reversed it would act like this, right? Seems like I did it correctly I think the magnets were at the back of the motor (away from the shaft) and I believe that's how I put it on.

I don't think I could have reversed the brushes around either. I'm pretty sure I put the motor/ratchet arms back where they were when I started but that shouldn't have made a difference, right?

Could the connector go on backwards... nope, just checked.

What am I missing?

[flyhop]

Great news about getting things to work right. I think your method for accessing the motor was easier than mine, but remember that I had the top that would not operate and the 5th bow was locked to the top of the tonneau. No way to get to the latching motor for me.

As to reversing the motor, I do not know. I would certainly try to switch the magnets around, but I can't see what difference this would make. I can't imagine that the gearbox/motor connection is reversible, but not having pulled it apart myself, I can't say for sure.

Try both and see what happens.

p.s. would it make a difference if the magnets were put in upside down? I may be showing my ignorance of how motors are assembled here (seems like the magnet would be keyed to fit in the spring, but magnets do have a polarity to them. If they could be put in upside down, would that affect the direction of the motor?

[john bernard]

Vespa

You might not like to do this, but I suppose a cheap and dirty trick would be to cut, switch and splice the wires from the ten point connector to the latch motor.
Remember that power to 8 should unlock, power to 9 should lock

[Vespa]

Originally Posted by john bernard

Vespa

You might not like to do this, but I suppose a cheap and dirty trick would be to cut, switch and splice the wires from the ten point connector to the latch motor.
Remember that power to 8 should unlock, power to 9 should lock

Yeah, I might go that route. I'll try and extract the pins and flip them around first. If that fails I'll probably change out the connector at the motor side.

There's a type that seals on the back side of the wire as well as near the inner edge of the connector that keeps liquids out. Wish I could remember the name so I could source them. Black connector, green seals.. hmmm

I'll make sure I check voltage readings at those pins while I have my wife flip the top lever. Am I measuring from chassis ground to the pins (positive) or between the two pins and I should get positive on the active pin relative to the other?

[Darren900]

Originally Posted by Vespa

There's a type that seals on the back side of the wire as well as near the inner edge of the connector that keeps liquids out. Wish I could remember the name so I could source them. Black connector, green seals.. hmmm

The connector is most likely either made by AMP (Amphenol) or Deutsche as they make some of the highest quality sealed connectors in the world. I don't think either company will sell to you directly, so go through a supplier like www.digikey.com

[Vespa]

I almost forgot, I live in farm country central. I can hop over to an implement dealer. They GOTTA have that connector I'm thinking of. Raven spray systems use it.

Or, I can just cut the wires and wirenut them together! So pro.

[john bernard]

Edit: In normal operation, ie thru 10 pin connector, grounding is done by and thru the control module to chassis
You could use wire nuts it'd work. Or be elegant and use a crimped butt connector (Autozone or Napa)

[Vespa]

Here's something interesting. While playing around with the latch assembly tonight I decided to grab an old 12V power supply I had laying around. It was rated for 3 Amps max. I still used the 8 Amp slow-blow fuse from yesterday just in case the one in the power supply was too large (I didn't bother checking to see what rating it was).

Anyhow, the 3 amps was plenty to force the motor to move the latches so that saved me some time. yea

I still have the reverse direction issue but everything else is ready to go. I'm not sure how I'll pop the pins out of either connector. I'll have a closer look at what's holding the male pins on the motor side tomorrow and see if I can get them to come out gracefully with a small precision screwdriver.

Kind of wish they were molex, like on a PC power supply. I've got one of those pin poppers!.

[Vespa]

Got it! Weather Pack. That's the name of the connector type. This place has them:
http://www.pegasusautoracing.com/pro...asp?RecID=5706

I'll try to get a pair locally first.

[flyhop]

I'm still scratching my head over what could have caused this motor to operate in reverse.

But you're in it for the solution, so if switching the wires works, do it.