I'm new in the sense that I've never posted anything before but I have read countless hours of posts here to fix my XWD and I just thought I'd share everything I learned to perhaps help some other hapless soul with a similar problem. My car is a 2008 Aero 9-3 XWD with the 6 speed manual tranny.
Service XWD first beeped up on my dash last July after I dumped the clutch a bit in a gravel lane. Once I got out on pavement, I instantly noticed intense torque steer. It was midsummer so I didn't need it that bad so I just drove it with the Service XWD message always on. I had also just bought a Nissan Titan so I was planning on fixing the problem in my spare time and selling the car.
I took the car to Merchants tire and asked for the code that was tripping the Service XWD light. 100 bucks later they told me the transfer case was cracked and had leaked all the fluid out which fried the transfer case. Code was U0001 which is a BUS communication code. I didn't see the connection between code and transfer case so I took it to Amco for a second opinion. I attempted to explain my doubts about the alleged transfer case being the problem as there's no electronics in the transfer case to throw a code. I also reiterated that they needed a scan tool that could communicate with all the cars modules, not just the main ECM. They said they understood exactly what I meant and that they had the right tools so I paid them their 90 buck diagnostic fee. Came back to pick it up and they told me that there were no codes whatsoever and that they were certain the transfer case was the problem. They gave me a $3300 price and asked if I wanted them to go ahead and do it. They had no explanation of what was making the Service XWD light pop up.
I didn't trust their analysis so I took the car up to my neighbor who has a small shop with a lift. We picked the car up, turned the ESP off, and started it up. The driveshaft going from the transfer case to the rear differential turned fine, the transfer case didn't seem to get hot and made no odd noises. (the back wheels turned as well actually, but I believe that was only because with no load on the tires any tiny bit of friction between clutch plates in the rear differential would turn the tires, even with clutches disengaged) My neighbour asked if they had checked the transfer case fluid level. I assumed they had but he went ahead and checked it through the fill plug (the exhaust goes right past the plug and makes it a PITA to remove but it's doable). Turns out fluid level was right below the plug. We did discover a small crack in the transfer case cover so I decided I'd drain the fluid, jb weld the crack, and fill it back up. By this point I was quite certain this had nothing to do with the XWD not working. I had to order the fluid online, so when it came in a week later I drove the car on jack stands and pulled out the drain plug. It did seem to have a fair amount of fluid in it. The crack went from the corner of the transfer case cover to one of 4 bolts holding the cover on the side on. After I pulled the bolt, the crack didn't even go past the gasket on the inside of the bolt. I cleaned it up good, put a bit of jb weld on the crack for good measure, and filled out back up. The bottle of fluid wouldn't fit up in there so the only way to fill it is to get a small hose in the fill hole, thread it out from under your car, attach the hose to the bottle, and slowly squeeze the bottle to force fluid into the transfer case.
My neighbor put his snap on reader on my car but there was no option for Saab on it. He referred me to another local shop that had the correct scantool. Took the car there. Their reader showed code u2170 no communication with rear control module. They said the haldex control module was probably bad but it could be a wiring problem. I checked the fuse in the trunk fuse compartment and the xwd fuse was good. They gave me a wiring diagram of the BUS system. I went home put the back of the car up on jacks, and removed the main plug going into the haldex rear control module, which is mounted on the side of the rear differential. I had to buy the service manual of some sort from mitchell1 in order to find out where the bus lines from the haldex module went to. The bus lines went the haldex module to the esp traction control module located right behind the battery in the engine compartment. Pins D and K on the haldex plug under the car are the BUS lines. Pin F should have 12v if the car is on. I jumped pin D and K with the end of a bent paperclip shoved in each. I crawled out from under the car and checked for continuity between pin 13 and 14 on the traction control module plug. (this way you can check both data lines at once without having to have super long test cables to reach from the engine compartment to the rear differential, as well as 2 people) I had continuity with the paper clip in and didn't have it with the paper clip pulled out.
I was pretty certain that the haldex module had failed. I found a company online, called BBA Reman, that rebuilds automotive electrical components. It seemed legitimate, so I called them and it turns out that they have successfully repaired haldex modules before. I pulled the haldex module, which has 2 bolts that are really hard to get to. I finally got it off by holding the Allen wrench in a pair of needle nose vise grips. After BBA got the part, they tested it and it was dead. They were super helpful and found me a new one for $675 but it would have to be programmed to the car using a tech 2 scan tool. Also, there is a control valve that must be replaced with the module because they are factory calibrated together. Found a local shop that said they had a tech 2 scanner so I went ahead and ordered it. Once the module came in, I called the shop to schedule them to put the control valve and module in and program it. Apparently the guy I had talked to on the phone was new or something because the shop didn't have a tech 2 and the closest one I could find was an hour and a half away at a Saab shop. Called the shop and they do indeed have a tech 2. Get off work early one day and make the trip with module in hand. The control valve is behind the haldex module, and can simply be pulled out by hand once the module is removed. We got the new module and valve in, hooked the car up to tech 2, and programmed the new module. Tech 2 said the reprogram was successful. I started the car and waited, very nervously, to see if the service XWD light came back on. Sure enough, Service XWD beeped back on the dash.
I nearly cried.
The only good news was that code u2170 was gone and replaced with code c0407, which reads rear control module hydraulic pump motor open circuit. Paid the shop $180 for the install and reprogram, and headed home. I did some more reading on forums and figured it had to be either a bad hydraulic pump motor, or possibly simply low clutch fluid pressure. Read that the resistance on the pump motor should be about 16 ohms, so I crawled under the car and tried to test the plug that went from the pump to the haldex module. I couldn't get anything to show up on my tester but it was pretty hard to hold the plug and 2 test probes in 2 tiny holes. I removed the pump from the rear differential by removing 2 small bolts with Allen heads. There's 2 even smaller star head bolts that hold the motor cover on the motor and pump assembly, but you don't need to remove these. The pump is a bit stubborn to remove but it will come if you pry it with a screwdriver a bit. Be careful to not damage the o rings that seal the pump in the differential. One of war removed I could test it a bit better and found that there were only 2 ohms of resistance on the 2 wires going into the pump motor. I removed the 2 tiny star head bolts and pulled the cover off the motor. It looked ok but I did notice a bit of magnet chips on the motors rotor coil thing. I wiped a couple tiny pieces of magnet off the rotor and wiped out the inside of the motor cover. It turns out that one of the magnets attached to the inside of the motor cover had a small chip in it. I put it back together, and figured I'd hook it up to a battery to make sure it didn't work before ordering a new one. Turns out it did run once jumped to a battery so I figured the only thing causing the service XWD light could be low differential clutch fluid pressure. This made a bit of sense because a little fluid had ran out while we were changing the control valve. Autozone didn't have the clutch fluid, so I needed to order it online. I figured I'd put the pump motor back in so that dirt wouldn't get up in the differential if I needed to drive the car before the clutch fluid came in. Put it back in and hooked up the plug to the haldex module. When I started the car to to pull it off the jacks, lo and behold the only thing to bleep up on the display was Check OK. I figured it'd come up in a couple seconds, but even after I took a 3 mile drive the service XWD hasn't reappeared. Previously it would always appear within 5 seconds of starting the car.
I guess a piece of magnet in the hydraulic pump motor was keeping the motor from running right. I wonder if both the hydraulic pump motor and the module went bad at the same time or if the module was even bad at all. I think it was bad because 1, BBA said it didn't turn on at all, and 2, code u2170 disappeared after installing a new module. I suppose when I dumped the clutch, a gravel flew up and damaged either the module amd/or pump motor. I got it going earlier today, so it took me nearly 6 months to figure out. Hope this helps someone somewhere. There is really not much information on these cars out there, other than these forums. Never could've figured it out without you all, so thank you!
Moral of the story. Don't trust big shops if their diagnosis explanations make no sense. Also, don't burn out on gravels, no matter how much fun.
Service XWD first beeped up on my dash last July after I dumped the clutch a bit in a gravel lane. Once I got out on pavement, I instantly noticed intense torque steer. It was midsummer so I didn't need it that bad so I just drove it with the Service XWD message always on. I had also just bought a Nissan Titan so I was planning on fixing the problem in my spare time and selling the car.
I took the car to Merchants tire and asked for the code that was tripping the Service XWD light. 100 bucks later they told me the transfer case was cracked and had leaked all the fluid out which fried the transfer case. Code was U0001 which is a BUS communication code. I didn't see the connection between code and transfer case so I took it to Amco for a second opinion. I attempted to explain my doubts about the alleged transfer case being the problem as there's no electronics in the transfer case to throw a code. I also reiterated that they needed a scan tool that could communicate with all the cars modules, not just the main ECM. They said they understood exactly what I meant and that they had the right tools so I paid them their 90 buck diagnostic fee. Came back to pick it up and they told me that there were no codes whatsoever and that they were certain the transfer case was the problem. They gave me a $3300 price and asked if I wanted them to go ahead and do it. They had no explanation of what was making the Service XWD light pop up.
I didn't trust their analysis so I took the car up to my neighbor who has a small shop with a lift. We picked the car up, turned the ESP off, and started it up. The driveshaft going from the transfer case to the rear differential turned fine, the transfer case didn't seem to get hot and made no odd noises. (the back wheels turned as well actually, but I believe that was only because with no load on the tires any tiny bit of friction between clutch plates in the rear differential would turn the tires, even with clutches disengaged) My neighbour asked if they had checked the transfer case fluid level. I assumed they had but he went ahead and checked it through the fill plug (the exhaust goes right past the plug and makes it a PITA to remove but it's doable). Turns out fluid level was right below the plug. We did discover a small crack in the transfer case cover so I decided I'd drain the fluid, jb weld the crack, and fill it back up. By this point I was quite certain this had nothing to do with the XWD not working. I had to order the fluid online, so when it came in a week later I drove the car on jack stands and pulled out the drain plug. It did seem to have a fair amount of fluid in it. The crack went from the corner of the transfer case cover to one of 4 bolts holding the cover on the side on. After I pulled the bolt, the crack didn't even go past the gasket on the inside of the bolt. I cleaned it up good, put a bit of jb weld on the crack for good measure, and filled out back up. The bottle of fluid wouldn't fit up in there so the only way to fill it is to get a small hose in the fill hole, thread it out from under your car, attach the hose to the bottle, and slowly squeeze the bottle to force fluid into the transfer case.
My neighbor put his snap on reader on my car but there was no option for Saab on it. He referred me to another local shop that had the correct scantool. Took the car there. Their reader showed code u2170 no communication with rear control module. They said the haldex control module was probably bad but it could be a wiring problem. I checked the fuse in the trunk fuse compartment and the xwd fuse was good. They gave me a wiring diagram of the BUS system. I went home put the back of the car up on jacks, and removed the main plug going into the haldex rear control module, which is mounted on the side of the rear differential. I had to buy the service manual of some sort from mitchell1 in order to find out where the bus lines from the haldex module went to. The bus lines went the haldex module to the esp traction control module located right behind the battery in the engine compartment. Pins D and K on the haldex plug under the car are the BUS lines. Pin F should have 12v if the car is on. I jumped pin D and K with the end of a bent paperclip shoved in each. I crawled out from under the car and checked for continuity between pin 13 and 14 on the traction control module plug. (this way you can check both data lines at once without having to have super long test cables to reach from the engine compartment to the rear differential, as well as 2 people) I had continuity with the paper clip in and didn't have it with the paper clip pulled out.
I was pretty certain that the haldex module had failed. I found a company online, called BBA Reman, that rebuilds automotive electrical components. It seemed legitimate, so I called them and it turns out that they have successfully repaired haldex modules before. I pulled the haldex module, which has 2 bolts that are really hard to get to. I finally got it off by holding the Allen wrench in a pair of needle nose vise grips. After BBA got the part, they tested it and it was dead. They were super helpful and found me a new one for $675 but it would have to be programmed to the car using a tech 2 scan tool. Also, there is a control valve that must be replaced with the module because they are factory calibrated together. Found a local shop that said they had a tech 2 scanner so I went ahead and ordered it. Once the module came in, I called the shop to schedule them to put the control valve and module in and program it. Apparently the guy I had talked to on the phone was new or something because the shop didn't have a tech 2 and the closest one I could find was an hour and a half away at a Saab shop. Called the shop and they do indeed have a tech 2. Get off work early one day and make the trip with module in hand. The control valve is behind the haldex module, and can simply be pulled out by hand once the module is removed. We got the new module and valve in, hooked the car up to tech 2, and programmed the new module. Tech 2 said the reprogram was successful. I started the car and waited, very nervously, to see if the service XWD light came back on. Sure enough, Service XWD beeped back on the dash.
I nearly cried.
The only good news was that code u2170 was gone and replaced with code c0407, which reads rear control module hydraulic pump motor open circuit. Paid the shop $180 for the install and reprogram, and headed home. I did some more reading on forums and figured it had to be either a bad hydraulic pump motor, or possibly simply low clutch fluid pressure. Read that the resistance on the pump motor should be about 16 ohms, so I crawled under the car and tried to test the plug that went from the pump to the haldex module. I couldn't get anything to show up on my tester but it was pretty hard to hold the plug and 2 test probes in 2 tiny holes. I removed the pump from the rear differential by removing 2 small bolts with Allen heads. There's 2 even smaller star head bolts that hold the motor cover on the motor and pump assembly, but you don't need to remove these. The pump is a bit stubborn to remove but it will come if you pry it with a screwdriver a bit. Be careful to not damage the o rings that seal the pump in the differential. One of war removed I could test it a bit better and found that there were only 2 ohms of resistance on the 2 wires going into the pump motor. I removed the 2 tiny star head bolts and pulled the cover off the motor. It looked ok but I did notice a bit of magnet chips on the motors rotor coil thing. I wiped a couple tiny pieces of magnet off the rotor and wiped out the inside of the motor cover. It turns out that one of the magnets attached to the inside of the motor cover had a small chip in it. I put it back together, and figured I'd hook it up to a battery to make sure it didn't work before ordering a new one. Turns out it did run once jumped to a battery so I figured the only thing causing the service XWD light could be low differential clutch fluid pressure. This made a bit of sense because a little fluid had ran out while we were changing the control valve. Autozone didn't have the clutch fluid, so I needed to order it online. I figured I'd put the pump motor back in so that dirt wouldn't get up in the differential if I needed to drive the car before the clutch fluid came in. Put it back in and hooked up the plug to the haldex module. When I started the car to to pull it off the jacks, lo and behold the only thing to bleep up on the display was Check OK. I figured it'd come up in a couple seconds, but even after I took a 3 mile drive the service XWD hasn't reappeared. Previously it would always appear within 5 seconds of starting the car.
I guess a piece of magnet in the hydraulic pump motor was keeping the motor from running right. I wonder if both the hydraulic pump motor and the module went bad at the same time or if the module was even bad at all. I think it was bad because 1, BBA said it didn't turn on at all, and 2, code u2170 disappeared after installing a new module. I suppose when I dumped the clutch, a gravel flew up and damaged either the module amd/or pump motor. I got it going earlier today, so it took me nearly 6 months to figure out. Hope this helps someone somewhere. There is really not much information on these cars out there, other than these forums. Never could've figured it out without you all, so thank you!
Moral of the story. Don't trust big shops if their diagnosis explanations make no sense. Also, don't burn out on gravels, no matter how much fun.
