| SudzRA |
Feb 28, 2012 01:05 PM |
AWC hydraulic pump issue
Earlier this month I ran into a problem with my AWC hydraulic unit, and would like to pass on some info to the community.
On my way into work one exceptionally cold morning, (temp was around -25C), my hydraulic unit failed. Here's the timeline of events. I started the car up and let it warm up for around 5 minutes, like I normally do. Like other days when its been this cold, my tranny was very finicky, so I took care to not push it too hard. I got onto the highway, eased the car up to speed, and then drove about 10km at the same speed. I then needed to slow down as I came through a small town. I stopped at a red light, then as I was accelerating at the green, my service AWC system light came on, throwing code C161E. There is a TSB about this code about it coming on at very cold temps, a reflash. Did the reflash, no help. Diagnosis showed that the hydraulic unit was finished (didn't come on at all, even when applying voltage directly to it). Warranty covered the unit, and they acknowledged that it is a known issue.
We believe the cause was most likely related to the cold, especially since I drove very slowly for a short distance, and then at highway speed for a long distance with little change in speed or direction (this type of driving does not activate the pump). Once the pump finally was given the signal to turn on (accelerating from a stop at a slight bend in the road), the hydraulic fluid was so cold it would have had the viscosity of peanut butter, which the pump couldn't push through the lines. This caused the pump to overload and that's all she wrote.
Preventative measures? On very cold days, drive in such a way that the pump activates from time to time, for very short periods of time if possible. This allows the fluid to warm up properly. You can see this happening on the MID on the S-AWC screen.
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