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Discussion Starter #1
I've got a 2001 Saab 9-3 SE convertible. It started having problems throwing codes for lock up solenoid and incorrect gear ratio. I now believe that the transmission overheated and it blew because it was definitely blown when I took it out. I got another transmission from a Saab that had been in an accident with 55,000 miles and I put it in. I took it for a drive today and it immediately started having the same issues also the crossmember in the engine bay that goes across over the radiator was so hot it's called in my hand when I touched it I shut the car down immediately I had only driven it for a few minutes it's throwing incorrect gear ratio again. I don't want to blow this transmission so I'm not going to drive until I figure out why it has to be an electrical issue I had checked all the pins for resistance going from the TCM and the dad come up okay. I'm going to check them again soon as I can find the information with the PIN numbers and the ohms. Also the input and output sensors could be the problem but I would find it so difficult to believe that they were bad on my old transmission and on the new one I swapped in I would find it easier to believe that there is an issue with the wires going to Those sensors. Oddly enough on this new transmission they had ripped off one of the plugs that went to one of those sensors and I had to cut it out of my old wiring harness and wire it in which makes me think that maybe just maybe that plug was the issue all along but I don't know that seems to Lucky. So if anyone has any good advice I know I have an electrical issue I did change the TCM and it made no difference whatsoever if I can't track it down I'm going to have it towed to the dealership but I put a lot of time and effort into this car and I'd really like to be able to figure it out myself so any help is greatly appreciated thank you so much.
 

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Discussion Starter #2
I'm going to the junkyard to see if I can grab another TCU and the wires going from the TCU all the way up to the transmission see if I replace those if it'll solve the issue I'm starting to wonder why the cars and going into limp mode with something is catastrophic and if it could have anything to do with the ECU if this fails and I can't get any information I think it's time to have the car towed I've had good luck with Valenti of Watertown in Connecticut they seem to really know their stuff normally with something like this I would probably go to a transmission shop but I have faith in them and I'm going to speak with them first to see if they feel confident that they can solve this any help would be greatly appreciated
 

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Have you had it plugged into Tech 2? Tech 2 has a battery of tests it can run against the TCM and the gearbox itself which will help identify any problems with the electrical side.

On my '01, I found that something (person, animal) had damaged some of the wiring to the transmission near the coolant bottle. Have you inspected the chassis side wiring? Did the replacement gearbox come with the PNP switch, or did you reuse the old one? Did you reuse the old torque converter?

Incorrect gear ratio happens when the input speed sensor and the output speed sensor do not match with predefined maps... By seeing the input speed is X rpm and the output speed is Y rpm, the TCM knows what gear it's in. The error means the solenoids have selected gear A, but the speed sensors indicate the transmission is in gear B. That means either the speed sensors are wrong (VERY unlikely), the solenoids are not working properly (possible) or there is a mechanical problem (most likely, IMHO). My '01 had this issue - it could not shift into 4th, would throw the error then go into limp home. I tried everything (new solenoids, valve body, you name it) before replacing the transmission... the replacement worked perfectly out of the box.

Here is a 3rd party document on the AW 50-42 - it should have everything you need to troubleshoot. The link is good for 30 days:

https://1drv.ms/b/s!AqwvoBt9ZBp2gfhxyItzJetUJUoj6w
 

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Discussion Starter #4
Thank you for your reply I have not run it on the tattoo that's the one thing I haven't done and I wish I could hit maybe going to the dealer so that may be happening but there is one thing that I was told could be the cause of the problem I use the wiring harness that came with the new transmission or the used transmission. The wiring harness had one of the speed sensor connectors ripped off. I took one of my speed sensor connectors off the old harness and crimped it in I was told now that I need to take those wires and reconnect them with a solder and it shrink wrap and that may be the issue. This is a used transmission so it could be mechanical I opened up the transmission and changed all the solenoids to brand new. So I don't think it's going to be a solenoid issue. What is the PNP switch you talking about the range switch the neutral safety switch. I feel like it could be an electrical problem with the connectors that go back to the TCM because that's the only part That Remains the Same although it is possible that this transmission has the same exact problem as the old one I feel that's unlikely so I'm going to start by soldering those wires together and see if that makes a change the next I was going to try to change the wires going back to the TCM then after that it's got to be scanned because I don't think I can take it much further thank you so much for your info it's greatly appreciated.
 

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Discussion Starter #5
I did use the torque converter that came with the used transmission it came out of a car that was hit in the front lately it had 55,000 miles on it when I opened up the valve body everything seemed to be pristine the Plastics were in great condition around the wires it really appeared to be a pristine transmission.
 

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Sounds like you're doing all the relevant things. Tech 2 can read the speed sensors directly, so that'd be a good place look. Do you get the same gear error in all gears, or only some?
 

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Discussion Starter #7
I believe it's happening in all gears when in drive. If I'm gentle on the gas and baby it through first second and third it almost seems like the car is driving okay. But if I hit the gas hard the problem becomes immediately evident because the car hesitates and doesn't know what to do no matter what gear its in. I put the car in first gear and drove it and it seemed to be normal in first gear. The car doesn't always want to go into reverse right now it seems I have to put it into drive first and then back it down to reverse to get it into reverse that may have something to do with the neutral safety switch on this used transmission that I just put in. That only seems to be compounding the problem. From what I understand if the neutral safety switch was bad the car wouldn't go in the gears but as far as the car not knowing where it is that has to do with the speed sensor and not the neutral safety switch so I'm trying to fix that problem first and then if I need to fix the neutral safety switch I'll do that. I can't really drive the car because it quickly gets so hot that I know if I drive it too long I'll blow this new transmission. So I'm going to start with soldering these wires together. If that doesn't work I'm going to try to grab some wires from the TCM to the unit and switch those out and if that doesn't work I believe it's time to get somebody with a Tech 2 on it and see if they can tell me why this thing is driving me crazy. I really love this car so it's breaking my heart that no matter what I do I can't get it back on the road. It seems like this cars just been a really unlucky car somebody abused it really badly and I've done more working on it then driving it since I bought it three and a half years ago I'm embarrassed to say how much money I've sunk into this car and that's what me even doing the work myself. But I really appreciate you guys helping out it means a lot so thank you.
 

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The PNP switch ("range sensor") is instrumental to the proper functioning of the transmission. If it's damaged or misadjusted, all sorts of weird things can happen, including damage.


The range sensor tells the TCM what gear is SELECTED by the shifter, and then the input/output speed sensors tell the TCM whether the hydraulics worked properly or not. Everything has to work exactly right for the transmission to not destroy itself. If the shifter is in D, but the PNP switch indicates N the TCM will improperly signal the solenoids and all hell breaks loose. It only takes a couple overheats to ruin a good transmission.


Tech 2 can show all of these things - it can show what gear is indicated by the PNP switch, it can show what solenoids have been commanded to what position, and it can show what the speed sensors are indicating. You can get a very complete picture of the transmission with it.


If you are not sure 100% about the electronics (TCM, wiring, PNP, sensors) I would not drive the car. Screwed up electronics can ruin an otherwise good transmission.
 

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Discussion Starter #9
I agree I'm going to throw in my old range switch cuz I didn't have a problem with it that I know of. And I'm going to go ahead and side of those wires together see if that does anything and I'll let you know hopefully I'll get to do it today thanks again
 

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I was asked to come over here from the 9-5 forum since I went through some of these issues with my 5-speed transmission a while back. I don't know a whole lot about the 9-3 and the 4-speed so bear with me.

First, on the 5-speed the "short to B+ or ground" error code on the linear solenoids is almost always a failure in the TCM. There are so many of those on the 5-speed 9-5's and almost every one has been fixed by replacing the TCM. However, shorts in the wiring can cause failures of those drive circuits so you need to check for shorts. But on the AW55 9-5's there have been a number of failures of the TCM that apparently happen for no real reason

Second, the speed sensor can be wiring but often is a failure inside the transmission. The TCM knows what gear the transmission is in and can compute the ratio between the speed of the input shaft and the output shaft. If it doesn't match it'll throw the incorrect gear ratio code. If it doesn't see any output from either of the sensors it will throw the no signal code. The "NSS" or range selector has really nothing to do with this, that just tells the transmission controller how you want it to behave (e.g. put the transmission in low) but the TCM is going to be looking at what it "is" doing when it is shifting to make these measurements. But if the sensors are working and the wires are good this is likely a mechanical failure.

The Tech 2 will allow you to look at the speed sensors to see if there are signals or you can use an oscilloscope to look at the raw waveform from the sensors. you can also check at the sensor to make sure that the bias voltage is being applied to the sensor (I think it is 12V)

I don't know what the specs are on the solenoids, but you can check them from the TCM end by attaching a good ohm meter to them. On the AW55 the linear solenoids are something like ~5 ohms and the on/off solenoids are ~10 ohms. Cheap meters won't measure that low so you need a good one. A tech 2 can also activate the solenoids individually if you like.

One of the things I learned when I was dealing with my issues (mine was a short to B+/Ground in the shift solenoid) was that it wasn't dependent on time it was dependent on the number of shifts that the transmission did. If I drove a few miles in stop and go traffic it would fail in 10 minutes. If I got on the highway cold and drove for 100 miles it wouldn't fail, but if I got off the highway and started in stop and go traffic, within 5 minutes it would fail. you have to be really observant on what is going on with the solenoid issues to try to figure out/reverse engineer how the transmission is behaving. (if you want to look at the trials and tribulations of what I went through look here: https://www.saabcentral.com/forums/showthread.php?t=245766&highlight=P0785)

What leads me to believe you have a wiring problem(and maybe a TCM problem) is that you have two of these codes at the same time and you've changed the transmission but still see the same errors (very low probability!). If you put the new TCM into the car and didn't check the wires you could well have "blown" that because of a short. TCM's are reasonably cheap and much easier to change than the transmission. I'd get my hands on another TCM and scope out and make sure you don't have any shorts between wires and shorts to ground in the wiring harness. On the 9-5 there is a large connector under the battery that connects the transmission harness to the chassis harness and that can get corroded. Don't know what you have on the 9-3 but I'd be checking stuff like that.

Good luck!
 

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Discussion Starter #11
Thank you Uncle miltie that was some really good info. I did grab another TCM so I have a third one now that hasn't been put into the car and I'm not going to put it into the car until I check the wiring like and said my car has been done over I've restored it to almost perfect condition so there's definitely no corrosion underneath the battery but that is a good point to check. Like I said one of the speed sensors was ripped off so I'm going to make sure that that wiring is soldered and then I'm going to go back and check the wiring from the TCM again I have someone coming with a check to so after I do those two things it's going to get red with a tattoo and hopefully that will put me closer if I have to put another transmission I will I'll put in 10 more but I don't want to do it until I know it's going to sell the issue. Thanks again for your time Uncle miltie I appreciate it
 

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I apologize for the end of that message I should have read it over before I sent it in I'm actually at the junkyard working on a car pulling some parts from a Saab for my car. It's supposed to say I have someone coming with a Tech 2. Hopefully I will get some good information when they scan the car. My apologies
 

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One of the things I learned when I was dealing with my issues (mine was a short to B+/Ground in the shift solenoid) was that it wasn't dependent on time it was dependent on the number of shifts that the transmission did. If I drove a few miles in stop and go traffic it would fail in 10 minutes. If I got on the highway cold and drove for 100 miles it wouldn't fail, but if I got off the highway and started in stop and go traffic, within 5 minutes it would fail.
I would guess this happens because the codes are typically X errors over Y time. On surface streets the solenoids are constantly in action, so X:Y is very high. At constant cruise, the solenoids are in one position so X:Y is very low.

What sucks about the "incorrect gear" error is that it could be mechanical or electrical, and the only way you can know is by monitoring the TCM & solenoids to see whether they are acting correctly or not. You can drill down a bit without Tech 2 by using the shifter to see if isolating out a gear changes the behavior, but ultimately you will need to reference commanded gear vs solenoid vs speed sensor. As noted, Tech 2 also allows you to activate the solenoids individually so you can listen for a reaction at the valve body. I could not have found my "incorrect gear" / no 4th gear problem without Tech 2... Tech 2 allowed me to prove all the electronics were working, thus pointing to a mechanical fault.
 

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Discussion Starter #14
I've been told by a saab mechanic that a bad abs sensor can cause this problem.im assuming I don't have any bad abs sensors since I have no codes for and or brakes but it definitely got me thinking what else that I haven't considered could play a part in this.im hoping when I get to scan the car I'll get some clues to point me in a direction but I keep wondering if the ecu could play a part .im assuming that the ecu is overseeing the tcu to know what it should be doing but I have no proof of this.if anyone knows what role the ecu plays in the operating of the tranny or any thing else that can play a part please fill me in.i just ordered a copy of the wis and I'm buying a tech 2. So hopefully with those I'll be able to find out what's happening. im also going to read through uncle Miltie's woes with his 95 to see what he went through to solve his problems as he is amazingly well versed with Saabs especially 95s.thanks again for all the help.
 

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Discussion Starter #16
When I was told that a bad ABS sensor could mess with the transmission it was believable. I can definitely understand how if the transmission is using the ABS wheel sensors as part of their inventory of information a bad one could lead to a problem. The source for this information was a Saab mechanic who not only worked in a Saab dealership on Saabs all through the 90s and 2000 s but now owns a Saab only shop so he's definitely reputable and knows his stuff. I found far stranger things happen as a mechanic. I wasn't trying to say that the ECU can make the transmission do anything or can cause it to have any problems I was just wondering what if anything the ECU gets for information from the TCU. At this point I think I boiled my problem down to a couple possibilities especially after I read Uncle milty's thread and what he went through with his transmission has TCU and his transmission harness. In a nutshell he had a bad harness and he had to replace not only the harness and the TCU. After replacing the harness the car drove fine for a while he had already changed the TCU but he had to do it again it's unclear if this is because of the bad harness and him changing TCU prior to changing the bad harness or if the TCU was bad that he had changed . So what I've come up with is my car is throwing the po730 code which means incorrect gear ratio and what that means is it cannot read the two speed sensors correctly. This was the same code at through for the other transmission along with a TCC lock up solenoid code. So one of two things is happening. Either there is a problem with the harness of the new transmission and the car is unable to read the speed sensors correctly which is very possible because the new harness came with one of the speed sensor connections ripped off. I had to wire a new one in and it may not be wired in well enough to read correctly since it only needs to have a 10% discrepancy between the two sensors to throw that code. The other possibility is the problem never was with either transmission and is strictly a wiring issue which would lie somewhere between the connection for the transmission harness and the TCU itself. So at this stage I'm going to try and clean up the connection to the speed sensor solder it. If that doesn't work then pull the battery for an hour change the TCU again and if that has no success then it's time for the tech and to glean any information I can from it. There's always a possibility there's something wrong with this transmission but before I swap it out again I want to make sure as much as I possibly can that that's a good choice and not just swap it out because I can't figure out what's going on. The thing that's bothered me about this transmission and the original transmission is that in both from the problem was intermittent. And as far as I'm concerned other than people saying well when it gets hot the fluid gets thin and that can cause the transmission to act up yeah I get that but what about when the transmission is hot and it works fine for a half an hour then doesn't work fine for a half an hour I would say that doesn't apply. The real issue here is Heat. I believe that whatever the problem was with the original transmission it cause an overheat and actually did destroy the first transmission. The second transmission the one that's currently in it begin to heat up very quickly when I started the car I shut it down before it was able to get hot enough to do damage. But for that reason I can't really run the car very long to try to determine any of this because I don't want to do damage to the transmission mechanically. So I only have a few minutes to determine if anything's been successful after the changes which only makes it more difficult. It's funny I've read so many people's threads on their transmissions and that they've taken them to dealers or shops and they had to have their Transmissions replaced because of similar issues and I wondered to myself how many of those shops replace the transmission then realize that wasn't even the issue fix the issue which was electrical but never told the customer about it because they didn't want to let him know that the Transmissions was never at fault in the first place I don't know how high the number is but my guess is it has happened. It's quite interesting that everyone I speak to just says oh you got a bad transmission swap it out and my answer is always I wish it was that easy. As much of a pain as it is to swap a transmission it's much harder when you've got a ghost in the machine and you're trying to figure out the unknown I take a transmission swap over that any day. My car is just Gathering dust in the garage I've already missed the spring which is my favorite time to drive the car. I've accepted that the car is not going to drive again until I overcome this and I have no way of knowing how long that will take but I'm doing everything I can it's very frustrating. I don't know what it is about Saabs that makes people go to extreme lengths to keep them on the road but I've definitely surpassed anything logical and it's just my love of the vehicle that keeps me pushing on. That and the fact that I just don't give up and won't give up. I've certainly met my match though. I've never owned a car in my life that I spend more time working on then driving. Well thanks again I always appreciate all your guy's help it's so nice to have a group of people who are like-minded that you can speak with to get information and help I definitely know why they call us Saab nuts. LOL
 

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ABS does not interact with the transmission. My response was mostly sarcastic. The transmission is entirely self-contained, and provides outputs to the ECM for gear selection and torque limiting. The ECM is also isolated from the ABS system except in that the ECM gets road speed information from the ABS system and, if equipped, torque limiting information for TCS. This is all documented in WIS. You could rip the ABS system out of the car and everything but the speedometer and TCS would still work.

I dont know what type of sensors the transmission uses for speed input, but if they are VR sensors (like ABS sensors) then a bad signal could be misinterpreted by the ECM as the wrong speed, since amplitude varies with frequency. A Tech 2 can graph the input and output sensors for monitoring.

P0730 does NOT mean the TCM cant read the sensors correctly. What it means is that the wrong gear has been sensed. It COULD be a problem with a speed sensor, but it also COULD be a mechanical fault. The only way you're going to know anything ever is by plugging in a Tech 2 - or, I suppose a scope - and watching sensor outputs. Tech 2 seems like the better option since it gives you access to other monitors and activations from one place. A Tech 2 will also let you get malfunction codes from the gearbox which may prove useful. That P code is no doubt from a generic OBDII tool.

Get aTech 2. Seriously
 

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Best of luck. Hopefully a tech2 will reveal the issue.


this P0730 is the one dtc I hope I never encounter. I just inquired about a nice 9-5 for sale near me at a very good price, and it's only got one issue P0730.
 

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Discussion Starter #19
As far as I could tell the speed sensors on the transmission are exactly the same as the ABS sensors there just magnets. And I agree with you a Tech 2 is needed. I actually just started to thread yesterday looking for help on purchasing one. I picked up a Dell d630 laptop I haven't received it yet. But I'm hoping that that laptop will be sufficient to work with the Tech 2. Thanks for the information definitely good information.
 
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