GMC Technical Service Bulletins for P1221 code
2002 GMC ENVOY ELECTRICAL SYSTEM
2003 GMC ENVOY ELECTRICAL SYSTEM
2004 GMC ENVOY ELECTRICAL SYSTEM
2005 GMC ENVOY ELECTRICAL SYSTEM
2001 GMC SAVANA ENGINE AND ENGINE COOLING:ENGINE:GASOLINE
2001 GMC SIERRA ENGINE AND ENGINE COOLING:ENGINE:GASOLINE
2001 GMC YUKON ENGINE AND ENGINE COOLING:ENGINE:GASOLINE
2001 GMC 3500 ENGINE AND ENGINE COOLING:ENGINE:GASOLINE
2002 GMC 3500 ENGINE AND ENGINE COOLING:ENGINE:GASOLINE
2001 GMC B7 ENGINE AND ENGINE COOLING:ENGINE:GASOLINE