"Check AdvanceTrac" light comes on

Most "economy" code readers an only access generic OBD2 codes... these are the ones that deal with emissions related concerns and do not vary from one manufacturer to another.

Sice your problem seems to occur only when it freezes, one might assume that moisture in the shift motor might be freezing keep the unit from functioning. Without knwing what the code or codes are, this is nothing more than a guess. Any of these systems are way too complicated to trust a guess. As Sherlock Holmes used to say... "Quick, Watson, the code..." (apologies to Sir A Conan-Doyle).

I can't stress the importance of codes enough.... these are the same as computer error messages or telling the doctor exactly where you hurt. The light is saying there is a code there... once we know the code and the symptom, we can try to discover if the code is causal or symptomatic.. but it gives us a direction to go. I'm not saying that something can't get fixed without knowing the code, but it sure makes the process less painful and shorter...

Jim:

Thanks for the reply. Do you know of any economy code readers that could read the codes from the 4x4 module?

One more piece of info. The light will come on with key-on, engine-off. The system seems to go through some sort of self-test at this point. Any idea on what it is testing? I wouldn't expect it to move the 4x4 shift motor, but you never know.

Also, it doesn't have to be quite freezing to trigger the problem. 40's will do it.

Thanks, Larry

Well, due to lack of information availability, I've taken it to the dealer. They tell me the codes are P1836 and P1837. That would be front and rear speed sensors mounted on the transfer case. They want to replace both for $492.

It sounds suspicious to me that both would go bad at the exact same time.

I told them to fix it. I don't have it back yet. Time will tell if this is the right fix.

Larry

I have a 96 Explorer, just had both sensors replaced by the dealer. Total cost 354.91 Part numbers 1L2Z*7F293*AB ($46.16) and 1L2Z*F293*BA($48.81). Labor239.85. Is there any reason yours would be so much higher?

Hello:

This morning the light is back. The fix didn't do it. Back to the dealer on Monday...

The final cost was $452 for the sensors. Probably so expensive because it's California. $85 total for parts, the rest labor. I know it only takes about 10 minutes to change them. I have no idea how long they actually spent on that or the diagnosis.

Larry

Hello:

Today I brought the explorer to the dealer for the 3rd time to address this problem. The first time they replaced transfer case speed sensors. The second time they cleaned some connectors and "updated pcm calibration." Today the light is back on. So even with all the right toys they still can't seem to figure this out.

Personally, I am leaning towards the 4x4 control module. It's my belief that electronics will be more temperature sensative than the mechanical parts, and this problem only happens on cool mornings. (Cool in CA is 45 degrees.)

Larry