Ok so I take the CRD out of the nice warm garage and start up the freeway to go play in the snow. (Ya I know it's hard to believe that it snows in AZ). Anyway, it's about 34* degrees outside and the transmission light comes on! Drives ok, stays on for about 20+ miles and then goes out. Not overheating here.
So I drive back home and it is just fine. No light. I scan the whole system with my Auto Enginuity scanner and no codes or anything. Wassssup with this?

Is this normal behavior for CRD's?

Could you have gotten enough snow and ice in the radiator area to restrict the airflow? That would be my first thought.
Second thought is a faulty connection at the transmission.

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

Yeah that. I had the tranny light come on (as did another CRD) on the high-altitude trails of CO when 4-Lo wasn't engaged. The thin air drastically reduces fan efficiency. I believe the trans cooling is the bleeding edge of minimal on these rigs and it doesn't take much to cross over to the not good enough.

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2006 CRD http://www.UtahPowderCoatings.com/ http://www.gorecon.com/ I'm kind of a big deal.
RL rear bumper, ARB front bumper, Mile Marker winch, Power Tank, Skids by Mopar & Skid Row, RL Super Skink Sliders, 235/85R16 MTR, Air Flow Snorkel, DTT, 4.10 gears, Frankenlift II, Katskin leather, JL Audio stereo, Rosen video.

The light came on while driving down the interstate at 70 MPH. No snow or rain yet, just ice cold air going through the radiator. Temps were normal. I was on my way to the snow.
I changed the tranny oil about 7K miles ago and level is good, no stink, not funny looking.
Maybe just a bad sensor or wiring? We'll see.

If the light came on there should be a code stored...

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2005 CRD Limited Flame Red w/ Renegade rock rails & light bar, AirLift 1000. 225/75R16 MT/R's on cheap black steel wheels, dual MOPAR subwoofers, Ipod kit & seat covers, Samco hoses - totaled and gone. 2008 WK Laredo 3.0L diesel - AirLift 1000, wife won't let me mess with it much. 2013 JK Sahara on order.

Are you are talking about the "Trans Temp" light?

I had that light come on when driving in limp mode and toasted my transmission, torque converter got so hot that it blued the steel, and it did not throw any codes.

I've pulled trailers (my 7.5x20 car hauler box comes to mind) that made the engine temp gauge rise... And never seen the trans light.
Dragging it home empty when I bought it, I couldn't get above 65mph, but I blame the mismatched and one flat tire for extra drag. Sway and drag problems went away when I fixed the tires... Even pulling that same trailer FULLY LOADED in summer, at about 7k lbs total didn't make the trans light come on.

Sounds like you might have something else going on.

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Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

Out in your neck of the desert, don't you have lots of corrosive alkali dust?
I would un plug the plug going to the offending sensor, spray it with contact cleaner (Like Wurth), plug it back in and see if the problem goes away. If it does, fill the plug with the electrical grease to keep out the dust, and plug it back together.
When I had the shop, other shops would start changing out parts and rack up the bill with no results. I would clean the plugs first and test before I ordered parts.

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2006 Pearl Green CRD
Magnaflow 2 1/2" Cat Back
KJ Extra Leg Room Brackets, Carter Lift Pump, V6 Airbox, ORM
Fuel cooler, Oil Separator, Progard 7
Gauges EGT Boost Trans Temp Oil Pres, Michelin LXT AT2 245 70 R16
7,000# Draw Tight hitch, PML EX Deep Trans Pan
Centrifuge, SunCoast, Transgo, RAM TCM, InMotion Stage 2
Wife's 99 TDI VW Beetle