[jeanguenat]

I am not getting any of the electrical codes, so I will assume my problem is not in the IGNITION SWITCH. I always thought that was some kind of inside-Blazer-joke on this forum...like a left-handed-smoke-shifter or something.

Post this TSB too blazee:

Harsh 1-2 Upshift and Possible Diagnostic Trouble Code (DTC) P1870 (Replace Valve Body) #01-07-30-023 Harsh 1-2 Upshift and Possible Diagnostic Trouble Code (DTC) P1870 (Replace Valve Body) 1996 Buick Roadmaster 1996 Cadillac Fleetwood 1999-2000 Cadillac Escalade 1996-2000 Chevrolet Camaro, Corvette 1996-2000 Pontiac Firebird 1996-2000 Chevrolet and GMC C/K, M/L, S/T, and G Models 1996-2000 Oldsmobile Bravada with 4L60-E Automatic Transmission (RPO M30) Condition Some owners with vehicles built before January 15, 1999 (Julian Date 9015) may comment on a harsh 1-2 upshift and may also have a check engine light. The scan tool may show a DTC P1870 set as a history code. Typically, these vehicles will have been driven more than 32,000 km (20,000 miles) to exhibit this condition. Cause The condition may be due to wear in the control valve body.

I need to pick a better Blazer Forum name. I hope nobody has picked BlazerDude.