1997 Blazer LT AWD transfer case 4x4 switch

[vanguard7]

My '97 Blazer started shifting funny lately and the "check engine" light came on at same time. Took the vehicle to Auto Zone to do diagnostics and it returned the code "P1870". Translated to 4x4 transfer case switch. They had the part it called for and Chevy also gave me a diagram of the transfer case and the switch's location. I crawled under the vehicle but could not find anything where the switch was supposed to be at. I subsequently found the transfer case is a Borg-Warner 4470 and photos of that doesn't show any kind of switch located on it either. I have a Hayes book but it doesn't give any location of the switch or if there is some alternate location for it. Can anyone please tell me if there is another place where this vacuum switch could be? It's supposed to have 3 vacuum lines running to it. I did find some kind of switch along the right side of the transmission right above the filter and am wondering if maybe this could be an alternate place. Apparently the full-time AWD versions of the Blazer utilize the Borg-Warner 4470 transfer case. Please somebody help me because I am really at a loss for ideas now. Thanks in advance.

[Jeremy-WI]

If the code was P1870, does it have a hard first to second gear shift?

[vanguard7]

to be honest I only drove it a few blocks. My ex to be has been driving it and brought it by the other night after a 100 mile round trip and said it just started shifting funny that night. According to her, the "check engine" light also came on about the same time and has remained on. I took it to Auto Zone to check the computer's error code and all it said was faulty relay in the transfer case 4X4 switch. I bought the switch it showed as needing replacement and found out the switch goes into the top of the transfer case but this vehicle has the Borg Warner transfer case which does not have any place for a switch on/in it and all the documentation I've been able to find so far doesn't say anything about where the vacuum switch goes if the vehicle has the BW case.

[Jeremy-WI]

There is something else a P1870 is for, on a vehicle with the auto tranny it means transmission component slipping.

[vanguard7]

Thanks, I finally got a Chevy shop to tell me that it could also mean tranny slipping and that it is internal but anything more can't be diagnosed without taking it out and apart. Guess now I've just got to figure out what to do about the vehicle. Thanks for all the insight/replies.