Vehicles equipped whit a 4 speed automatic transmission may develop a harsh 1-2 shift and/or illumination of the Check Engine Light with code P1870 stored. This can be caused by wear of the bore for the TCC isolator and regulator valves in the valve body. This condition does not commonly occur until the transmission reaches normal operating temperature. If the valve body is worn, replacement will be necessary to correct this concern.
Check Engine Light With Code P1870 on Chevrolet Silverado 2500
Average mileage: 152,000 (152,000–152,000)
Drive Train affected: Automatic Transmission
3 people reported this problem
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After driving for about 20-30 minutes on the highway, then once I come to a stop it will shift hard. Also if it is shifting hard it will usually stall when I put it in reverse.