Why check engine light comes on
When I put my 1995 gmc 1500 into gear the engine light
comes on it goes out after I get up to 2200rpm and comes
back on when rpm drops 1995 gmc 1500 with an 4l60e 4x4
and a 6.5 non trubo
Pull the code and see what it tells you, once the light comes on it stores the code until the system is reset.