Posted by gregsachs on 2/11/07 on IWSTI
http://www.iwsti.com/forums/1125049-post9.html

on the 04, the dccd trouble code could be pulled by the following procedure:
engage parking brake
turn ignition to on
set dccd to min
fully depress throttle
turn dccd dial fully to max, then back to min. repeat this 10 times
It will flash 2x/sec if there is no trouble code
If there is a trouble code, a 1.2 s flash indicates a 10 digit, and a .2s flash is a 1 digit. So 1.2, 1.2, .2, .2 would be a 22
diagnostic procedure:
1: engage parking brake
2: set dial to min
3: start engine
4: set dial to max
5: release parking brake
6: set dial to min
7: engage parking brake
8: repeat 4-7 twice in 30 seconds
(will now get a trouble code display)
9: operate parking brake
10: operate brake pedal
11: operate manual mode
12: operate dial and set to max, wait 3 seconds
13: drive above 10mph for at least 5 seconds and check the indicator status light
At this point if the system is happy the next ignition cycle will clear the dccd trouble code
There are only 7 dccd codes, 11, 12, 13,14, 21, 22, 23. Rear diff sensor is not a trouble code, just an override condition that will clear as soon as temp is ok.