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"Check AdvanceTrac" light comes on

Jim:

Thanks for the reply. Here is what I know so far:

1) My code reader will not read any codes from the 4x4 module.

2) The problem only happens when the car is very cold, overnight on a freezing night. If it doesn't get cold, the light does not come on. The coorelation to cold nights is pretty strong.

3) The light can be reset by removing the 4x4 fuses (#17 and #18). If I do this when the car has been warmed up the light will stay off until the next cold morning.

4) If I reset it by removing fuses, 4x4, including low range, works fine. If the light is on, no 4x4 action is possible.

5) I have read about others having issues with the transfer case shift motor. I played around with this a bit with no effect. I removed it, checked alignment, slightly moved the encoder ring in each direction, etc. I did this on a cold morning when the light will stay on, and none of my adjustments changed anything.

6) Build date is May 2002.

7) Two or three times over the life of the vehicle until now, the light has come on for one start cycle and then reset the next time I've started the car. The issue never stayed around, and didn't seem temperature sensative.

Pretty much, I'm shooting in the dark here. Before I take it to the dealer, any ideas on what components in the system would be temperature sensative? Anything I can do without reading 4x4 trouble codes? Any info would be helpful.

Thanks, Larry

It will depend on the code reader.. Some code readers can't access >proprietary modules and are designed for PCM code retrieval only. For your >concern you will need to access the 4WD module. Diagnostics will depend on >whether yours in a Job 1 or Job 2 car... > > >> Hello: >> >> I've got a 2002 Explorer Limited with v8 and AdvanceTrac. It has >> 50,000 miles. Today the message center comes on with the message >> "Check AdvanceTrac". In addition, the 4x4 lights will flash >> occasionally and the 4x4 buttons no longer have any effect. The >> AdvanceTrac icon on the dash stays lit. >> >> Any ideas on what to check first? Will an OBDII code reader be >> able to read the error codes for this sort of fault? >> >> Thanks, Larry >
Reply to
Larry Brown
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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...

Reply to
Jim Warman

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

Reply to
Larry Brown

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

Reply to
Larry Brown

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?

Reply to
jrchilds

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

Reply to
Larry Brown

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

Reply to
Larry Brown

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