Question

1998 Chevrolet Blazer 4.3L with engine code P1870, could this be transfer case related?

Answer 1

P1870 Transmission component slipping

Highly unlikely, what the VCM uses to monitor for a slipping transmission is the engine speed and the output speed , when the TCC (torque convertor clutch) is engaged the engine speed should match the output speed. This is a "B" type code condition this can be intermittent condition , check the transmission fluid level and condition,

Answer 2

P1870 CHEVROLET - Transmission Component Slipping

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