1999 Chevy Blazer

GEESSPOTS

MEMBER
1999 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
189,000 MILES

I have a 1999 chevy blazer and am having shifting/tranny problems.

under light acceleration the truck surges as if it is going to shift up but then changes its mind and then shifts up.

took it to tranny guy who tells me its not the tranny itself but that the computer is saying the truck is in 4 low when it is in 2 high so it is shifting in low range while driving in high range.

took it to chevy dealer whos says nothing is wrong with it but that it gave a error code B1875 ( I think that the code is actually P1875)

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Hi:

Your trans mechanic is correct. A P1875 deals with the lo-lock 4wd. The transfer case module sends a signal to the engine computer when it goes into 4wd low so the engine will shift the transmission differently. First thing to do is to check the connector to the transfer case module, The transfer case module(TCCM) is located behind the passenger side kick panel (to the right of where the front passenger's feet go). Check the connector for water or crossion in it. If everything looks good, then chances are the module is bad or you have damaged wiring at some point.

Here is the actual meaning of the code:

P1875 -- Transmission Automatic Hall Effect Sensor Power Circuit Short To Battery / 4WD Low Switch Circuit Electrical

Let me know if this helps. Regardless, the trans tech is correct.

Joe