Code 12, No Rpm Signal: Notes

ECM monitors crank angle and camshaft positions, and supplies .7 volt to crank angle and Camshaft Position (CMP) sensors. As signal rotor rotates, voltage is toggled high and low. ECM determines crank angle and camshaft positions by toggled voltage input.

Code 12 will set if ECM does not detect crank angle input while engine is cranking for 2 seconds or more, or ECM does not detect camshaft position input with engine speed 600-4000 RPM for 3 seconds or more.

1. Checks for faults in crank angle input low circuitry and ECM.
2. Checks for faults in crank angle input high circuitry and ECM.
3. Checks for faults in camshaft position input low circuitry and ECM.
4. Checks for faults in camshaft position input high circuitry and ECM. Also for a misadjusted signal rotor air gap.