Test Notes

Normal Operation

NOTE: Circuit 620(P/LB) is riveted to the side of the LH air bag sensor case, and the case of the sensor is grounded to the vehicle at its mounting point.

The air bag diagnostic monitor measures the resistance between Pin C208-20, Circuit 620(P/LB), and the reference ground at Pin C209-18, Circuit 649(BK/O). If a difference of more than 3.0 ohms between the ground at Pin C209-18, Circuit 649(BK/O), and the ground at Pin C208-20, Circuit 620(P/LB) is measured, the air bag diagnostic monitor will store a Diagnostic Trouble Code (DTC) B1945 in memory and flash a Lamp Fault Code (LFC) 45 on the air bag indicator. Should the difference in resistance between Pin C209-18, Circuit 649 BK/O), and Pin C208-20, Circuit 620(P/LB), be repaired or otherwise reduced to less than 3.0 ohms, the air bag diagnostic monitor will store the DTC B1945 in memory.

Possible Causes
A high resistance reading on Pin C208-20, Circuit 620(P/LB) or Pin C209-18, Circuit 649(BK/O) can be caused by:
^ a poor attachment of the LH air bag sensor and bracket due to loose mounting, dirt, or corrosion at its mounting location.
^ an open or damaged wire in Circuit 620(P/LB).
^ an open wire or loose rivet inside the LH air bag sensor and bracket.
^ a poor reference ground at Pin C208-10, Circuit 650(BK/LB) or Pin C209-18, Circuit 649(BK/O).