On very slippery and snowy roads tonight, the AWD is not engaging. Only the rear wheels are spinning, making the truck very bad in the snow. There are no codes in the PCM and no MIL lights.
AWD not working on 2005 Saab 9-7x
Im not familiar with saabs. Is there a button to turn the system off?
No, the AWD is fully automatic. When the rear wheels slip, the system is supposed to engage the transfer case (which it had done for years successfully). I just noticed tonight that I had zero traction and I realized I couldn't feel the front wheels engaging. I ran my code reader on the PCM and have zero faults and no problems lights either.
Well it was worth a shot.. If there was a problem with the system i believe it would set a code in the ABS and not Engine management ie. check engine light. ABS will only illuminate if the problem is currently existing. I would try it again and see if the ABS light or traction light comes on while your attempting to get AWD. If it doesnt i would lean towards a mechanical failure. Or try scanning for ABS codes if your code reader has that capability.
I had my driveline guy repair it. The front and rear driveshafts were spinning the same speed so that is why the PCM thought everything was ok. The intermediate shaft and coupler were stripped out (splined connection). Replaced both parts and reassembled.