Getting a Code 12 on your GM’s OBD1 scanner? That usually means your ECM isn’t receiving the distributor signal, which affects spark timing and can lead to hard starts. Haynes Manuals give you the step-by-step help you need to trace the problem and get your vehicle back in shape. Don’t guess—get expert instructions at haynes.com. #HaynesManuals #GMFix #HaynesShowsYouHow | Haynes Manuals

4.3K views · 21 reactions | GM OBD1 code 12? It means your engine's RPM signal isn’t detected during cranking. Common causes include a faulty crankshaft position sensor, defective wiring, or a malfunctioning ignition module. Haynes Manuals helps you diagnose and fix the problem step by step. Find your GM manual today at haynes.com. #HaynesManuals #HaynesShowsYouHow #GMRepair | Haynes Manuals | Facebook