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Discussion Starter #1
Hey guys,

A while back I picked up a clean 54,000 mile 1995 900 with a soft top that didn’t work. I’ve been working with a Saab specialist to fix it, but seem to be hitting a wall on progress.

  • When I bought it, the release lever had already been pulled
  • The original SID that was in the car was totally dead when I bought it. Switched it for a good used convertible unit and it now works as it should
  • Car must think the top is down - trunk button on drivers door and key fobs don’t work
  • The rod out of the tonneau motor was majorly twisted just before the u-joint, as if someone had tried to wrangle it out. We installed a good salvage motor with a reinforcement kit
  • The softtop computer showed no signs of life, so shop swapped in a good one which cleared two fault codes
  • Shop said Tech 2 indicated potentiometer issue, but not where. Replaced potentiometer on tonneau motor with new Genuine sensor, no change
  • Shop said they could get 5th bow to move with a tech 2 but not anymore. When it did move the readings were backwards for up and down
My understanding is mostly second hand/what the shop is telling me, but from what I’ve pieced together on this forum the next culprit seems to be the 5th bow micro switch. Is that logical?

Anyone run into this before? I want to help the shop as it’s the only one in 300 miles willing to touch and reprogram it, but have already thrown a lot of parts at it.
 

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Bobsaabit may be a better source (where is jakejm79?). I'd say you want to look everything over carefully for evidence of amateur repairs.

Alternately, you may be able to source a good used top that works properly. Yes, that would have made more sense back before you invested money in the current top, but don't let the sunk costs fallacy get you.
 

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Try physically disconnecting the 5th bow latching motor.
If the top works while eliminating that potential major problem you'll know how to progress.
 

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Check this link for a great troubleshooting guide. http://www.saabservices.com/cvtop data/ng900cv top diagnosis and troubleshooting.pdf

I also attached a programming guide. Between a new SID, potentiometer and TSAS you probably need to reprogram the top and sid.

TSAS goes through initial system checks before it will allow the top opening or closing process to start. A trunk, front latch, or top storage bag open/close sensor issue will stop everything from working. you mention a trunk latch issue, the shop should be able to read if it is showing trunk latch open which will stop top from working. You can read all the top related sensor readings with tech2 to ensure the front latches are open and the top storage bag is in the open/ready position as well.

You can also step through the entire opening process activating each function one at a time with tech2 to pinpoint problem. Did you check TSAS fuse, harness connections and looked for obvious tears or cuts in the harness? Make sure switch is good as well, the top switch contacts inside can scorch and disintegrate.
 

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Discussion Starter #6
Thanks for the advice everyone. I showed this to the shop and they were able to isolate it down to a failed 5th bow sensor. Once that comes in we should be set! Will come back with the result.
 

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Discussion Starter #7
Update - the shop was not able to fix the 900 and has returned it to me. Here’s what I know:

  • Replaced tonneau cover motor & potentiometer
  • Replaced 5th bow switch
  • Following codes are still present: B1870, B2025, B2030, B2046, B2035, B1308, B1186
  • SID gives Check Latches alert
  • Shop said they could get the 5th bow motor to go up with the Tech2 but never back down
  • Shop thinks top computer could be bad
  • Checked all grounds and they were all OK
Any ideas? I’m feeling up a creek on this one.
 

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Any ideas? I’m feeling up a creek on this one.
Should be able to get a top computer in a junkyard for $25. They are rarely pulled at the u-pulls since they never go bad. I don't think I've ever seen anyone have to replace one. Might be some on Ebay.
 

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It'll be tough to troubleshoot at home without a tech2. I'd buy a clone as you will probably use it a lot more than you expect to keep your 900 happy. More than likely the top needs to be reprogrammed, especially after multiple people have worked on it and the potentiometer was changed. Reporgraming the 900 involves stopping it at various stages of the opening process and setting various parameters with Tech2 so they are all in synch. For example if it's not programmed correctly the TSAS might not allow the raised 5th bow to go down because the tonnaue poteniometer was not programed and the TSAS is getting a reading that the tonneau cover is not in the full open or fully closed position. It assumes the top will hit the cover so it stops the process. The shop should have been able to read the tonnau cover position when they were trying to lower the bow so it might not be that particular issue - but if any of the reprogramming sensors are far off - they can stop the TSAS from openign or closing.

Without a tech2, work on each error in the opening sequence one at a time. Check the windsheild latches first. The TSAS checks all sensors/settings before it allows the top opening process to start so if one latch is sending a closed signal, TSAS will not proceed with top opening or closing. Does the top physically align with the guide pins on the windshield when it is resting in the closed position? The receiving holes should be centered (or reasonably close). I think there are micro switches on the side of each latch, check them to see if they are bent, have bad contacts, connectors are secure, etc. Also be sure that when you engage the latches they are pulling the top down with some force so the top seats correctly against the windshield.

It can't hurt to swap the TSAS and they are readily available. Assuming the shop had some idea what they were doing, you might be dealing with one of those annoying very low probability problems like a wiring harness issue. Check the pins in the TSAS connectors carefully and I'd spend some time tracing the harness away from the TSAS looking for kinks, crushing, cuts, etc. Pull all the carpet out of the trunk and remove the driver side back seat panel. Part of the harness will loop around the trunk to the tonnaue cover motor, emergency release switch, tonneau close latch motor, side latch switches. Others up to the top's motors/sensors and a main lead up to the SID. I can' recall but it must have a connector under the drivers A-pillar. Check all connectors and pins, and wires. Maybe you had a hungry rodent or a prior owner with sloppy wiring skills who hacked into the top harness by mistake.

A tech2 would make it easier as you can activate or read each part of the puzzle. Step through the opening process until you hit a roadblock. Fix that problem and step through again until you hit another roadblock. I think one of the attachments shared listed each step in the top opening process. You can work through each step without a tech2, but it'll be a bit more involved.
 

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Discussion Starter #11
Thanks everyone for your feedback!

I made an interesting discovery tonight that I’m wondering if it could have caused some of the multitude of issues for the Dallas shop.

The car was totally dead tonight, and the battery could not be brought back with a jump. On top of that, it was entirely the wrong size for car and was so small it was able to slide around! For such an electric intensive top, could this tiny, old battery have caused the shops their headaches?
 

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They probably had the battery on a charger when working on it - even the correct size battery will drain quickly when you have tech2 attached and are playing with the top. That said, Saabs can have a lot of electrical gremlins caused by a battery with diminished capacity.
 
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