I have a '98 Blazer with a V-6. It is 4 wheel drive with high and low 4 wheel drive. After running a while it begins to shift hard from first to second. It seems to be delay and the engine rpm is continues to increase until it is higher than it should be before it shifts. I bought it used, I have 65,000 miles on it and changed the tranny fluid. The stuff that come out looked like it needed changing but not awful.

I experienced this a few times and then the check engine light came on. I had the code read at Autozone and it said the code was:

"P1870, Transmission Automatic 4 wheel drive indicator (lamp) Circuit Short to Battery" and "P1870 Transmission Mechanical Transfer Case 4X4 switch Circuit Short To Battery."

Neither of these seemed to be likely causes of a rough shift problem. I don't know where this switch is unless it is the one on the dash to select 4 wheel drive mode.

Any tips would be greatly appreciated.

Thanks,

R. Murphy

 

I have a -99 Blazer LT and have the same problem... shifting har dfrom 1:st to 2:nd gear after a complete stop,
but if i turn of the vehicle för 10-20 sek the problem is gone.

Have U experiensed the same?

I will go and read my code tomorrow!!