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 1500
Average mileage: 110,000 (50,000–160,000)
Drive Trains affected: 4WD, Automatic Transmission
5 people reported this problem
1 person shared problem details
2000 Chevrolet Silverado 1500- Automatic Transmission160,000Visitor
With the a/c on and the cruise control engaged on a hot day I get the hard 1,2 shifts with the p1870 code.
Check engine light comes on intermittently...especailly when hauling a load.
...tion check valves may become restricted causing poor air flow resulting in illumination of the Check Engine Light. It is often recommend to replace both check valves even if a fault code is set for only one...